Build Session 16 : Roll Over Bar, Some Engine Plumbing and Bonnet Test Fit with Nose Cone

This is a catch up post. Things had been busy with work and family stuff so I only had a couple of short periods that I’ve bunched up into one build session.

Sept 12th

Roll Over Bar

Whilst looking for something simple to do one evening I thought I’d have a go at the roll over bar.

Additional bolt going up into roll over bar. You can see the upper mounting bolt for the rear damper in the top left of the picture

Because I’ve upgraded to the track bar there’s an extra pair of bolts that have to be fitted from underneath into the base of the bar. This therefore means the roll over bar has to go in before the rear suspension – or else you can’t get those underneath roll over bar bolts in.

Not all of the holes lined up perfectly but they were good enough.

Holes don’t line up perfectly.

The rear mounting points needed a bit of persuasion to locate into the chassis but it wasn’t a big problem.

Track day roll over bar in place

Note from the future: I had worried that fitting the roll over bar at this point might cause a problem later in attaching the rear suspension. In the end it was no problem at all and actually meant I could fit the rear dampers when it made sense to. For some reason the manual tells you to wait to fit the rear dampers if the roll over bar is not in place, well that makes sense, but it should really tell you to fit the roll over bar at that point – IMHO.

Sept 16th

Top Radiator Hose

Again looking for a simple job I cut the top radiator hose to length. As with all the engine plumbing I’m leaving everything a little long if at all possible, I can always come back and trim it if needed – you can’t go the other way.

I used a pull saw to give a nice cut but otherwise a trivial job.

Cutting the top radiator hose to length

Water Expansion Tank Bracket

Ok… So… This one was going to be a little tricky. On a dry sump installation the water expansion tank can’t sit on the front chassis cruciform. It has to sit off to the RHS on a bracket that gets attached to the chassis.

The manual gives detailed dimensions for fitting the water expansion tank to a standard S3 chassis – giving a dimension from the engine bay centre cruciform along the front chassis rail to the bracket. The bracket that’s given is also drilled for the S3. So… on an SV you have to figure out where along the chassis rails this plate/bracket needs to go and then drill the chassis to take it. As you can see below the geometry differences of the S3 and SV chassis also mean the bracket holes don’t line up.

Water expansion bottle bracket. Note that I drew white paint lines along the top of the chassis rails to help me see where the holes in the bracket need to line up.

My plan was to measure twice, cut once. Well, actually it was more like measure 20 times… get the drill out… rethink… measure 5 more time… grind plate, drill chassis and rivet.

Initially, I was going to use rivnuts placed into the chassis and to screw the plate to the chassis through them. However, taking a few measurements of the chassis rails I wasn’t happy to complete on this plan. Firstly, the rails are only around 19.4 mm in diameter. I wasn’t happy to put anything much bigger than a 3mm rivnut into something that small. However, a 3mm bolt was not going to make a good fixing on the plate – it’s too small really for the 4mm hole in the plate. So… what about using 4mm rivnuts….

Well… that would be good for the plate holes but I wasn’t happy about the 6mm hole I’d have to drill in the chassis rails to take the rivnut – a lot of the chassis rail material was going to have to get drilled out and I didn’t want any structural problems later on – especially in any possible bumps.. I was also a bit concerned that putting what is essentially a device meant for flat surfaces into a chassis rail that has a tight radius on it would mean the rivnut would sit proud of the rail and may not even form correctly inside the rail. Choice made… use the standard rivet approach from the manual.

I got a bit OTT with all these machinations, and marked out the chassis rails with white paint to figure out where I was going to put things.

It seemed that the bracket/plate was going to have to sit some distance from the measurement given in the manual and so it came to mind that since it was moving closer to the edge of the car, I might move it too far and find it fouled with the bonnet – cue a test fit of the bonnet and nose-cone…

Bonnet (Hood) and Nose Cone Test Fit

This was exciting… an excuse to try a test fit of the nose cone and bonnet. The bonnet was still waiting to go back for a respray and the nose cone was squirrelled away in my office in the garden (along with most of the contents of the garage prior to this project).

Nose cone looking good. Not sure how central the badge holes are… that will need some thought at a later stage
Test fit of both bonnet and nose cone

After a test fit it was clear there was plenty of room for where I ended up wanting to put the expansion bottle.

Loads of room between nose cone and water expansion bottle where I thought it would be. There seemed to be around 15mm of clearance

One slight disappointment with this fitting was the discovery that I’m missing the 5/16″ hose that fits the small expansion bottle connection and connects to the rear of the cylinder head. That’ll be an email to Derek next week while I’m travelling.

While I was happy that I’d got the basic position of this bracket right I had run out of time and so this will have to wait until I come back from a business trip next week to Florida.

Here’s a couple of interesting pictures looking back towards the rear of the car with the bonnet on…

Looking down RHS of engine bay – nowhere near finished yet
Looking down LHS of engine bay – nowhere near finished yet

Build Session 15 : Odds and Ends, Bonnet and Radiator

This post is a rollup of a few days tinkering. I’m sure many of you will be relieved that I’m not going to spam you with any more posts than I absolutely have to, and so I’ll combine a few together.

Sept 5th – Bonnet Arrived (for a while)

The bonnet (Americanese: hood) of the kit had been the only known part that had not been shipped when the kit first arrived (if we ignore the shorts box that should have been on the van). It had a couple of defects that Caterham were going to get fixed and then send out. However, it had taken a few weeks before the van was back in our area, which wasn’t a problem since the idea of having the bonnet kicking around the garage was not something I really needed, given our small play area.

So the bonnet was dropped off by the Caterham delivery guy today in a rather snugly fitting cardboard box. I had half a mind to leave it in the box to keep it safe but decided I’d better check it had arrived ok…. unfortunately, it hadn’t. There were some scratches and scuffs on the paintwork at the rear of the bonnet. This is in stark contrast to the rest of the paintwork – which to my eye – is immaculate.

I emailed Derek and he assured me it had left the factory ok and he had no hesitation in saying that it would be sorted, just needed to find a time when the van was back in the area and could pick up the bonnet again. I’m not going to post pictures of the issue here, I think that would be an unfair publication of an issue that Caterham are on top of.

In the meantime, I needed somewhere to keep the bonnet safe while I waited. I’ve mentioned before that I have a trolley left over from the days of having a 911-996 C4Cab – used to store the hard top when not in use.

Bonnet Trolley

The new bonnet fits nicely on it (with soft rubber moulded rests for it to sit on at the bottom and foam pads at the rear).

Bonnet on the trolley

However, this was still going to get dinged if I left it in the small confines of the garage like that. So… a bonnet for the bonnet. I took some of the cardboard from the box that the bonnet came in and made a cover for it on the trolley.

Bonnet with it’s bonnet and trolley

Of course, I only spotted the defects on the bonnet after close inspection and after having created this trolley and cardboard contraption. My first look at the bonnet didn’t show any defects. It was only when I got really close that I saw them. That’s not to say they’re small, I just didn’t see them straight away. The point of this thread is to say… if I’d seen the scratches earlier then I would have put the bonnet straight back in its box and kept it safe there. But, I’d already broken down the cardboard box to use with the trolley. I guess it would also have been the case that if I’d have put the bonnet back in its box after a cursory look, then I probably wouldn’t have seen the scratches that night and it would have been weeks before getting it out of its box again. Swings and roundabouts.

Sept 6th – Test Fit Radiator and Heater

This week was turning into a week like any other… able to grab the odd hour or 30 minutes in the evenings away from a conference bridge. During one of those hours I started to see how the main water radiator, oil radiator and associated plumbing was going to work.

I’d already had a bit of a look at the radiator a couple a week earlier when I’d gone through the manual and tried to figure out where all the pieces for this part of the build were located. This is where I couldn’t find the “inner radiator cowl” as called for in the manual. I had sent an email out to Derek asking if I was missing it and got this response:

“We no longer fir the cowling to the 420R as we felt the cooling was better without it.”

This must be a reasonably recent decision as I’ve seen what I thought were recent blog posts from people where there clearly has been an inner cowl fitted.

Back to this test fit though… this time I wasn’t just “part picking” I was loosely hooking everything up and trying to figure out how this would work with no cowl.

There were two discoveries here:

  1. The manual describes how to fit everything together in the section on the Sigma and Duratec wet-sump engine build.
  2. I was missing the radiator fan legs. The radiator fan should have 4 legs that slot into the fan and have flanges that have holes in them to fix to the black “bat wing” extensions.

A quick email to Derek again and he popped the fan legs into the post. Even without the fan I was able to hook most things up and look at how I was going to drill out the holes in the SV extension brackets to take the upper oil cooler fixings.

The radiator extension brackets for the SV chassis attached to the outside of the chassis mounts

Its fairly obvious which way up the extension brackets go. One of the brackets was in my “shorts” box.

The bat wings sit behind the radiator and should have the fan at on them

I got as far as I could with a test fit of this section but decided not to do any drilling of the radiator extensions for the oil cooler at this stage.

Sept 7th – Heater

Another evening, another 30 minute slot to play with…  so I moved onto the heater. It seemed I needed to shift the battery by loosening its mountings and bringing it as far forward as it would go. Otherwise the heater refused to drop down behind the battery.

Shifting the battery forwards on its mounts

I put the passenger compartment vents in place (with the ears pointing downwards as recommended) and then put the heater unit into place.

Internal heater vents in place, view from driver’s side.

The heater then slots in-between the scuttle and the battery.

Heater sitting in front of the firewall/scuttle. Notice the plastic bows out from the firewall leaving a gap – not a problem IMHO.

As you can see in the image above, there’s a gap between the heater assembly and the firewall/scuttle edge. I’ve seen some people post and say they’ve added a bead of silicone to the heater edge to seal the gap. Perhaps I’ve got the wrong end of the stick with what they’re doing but I don’t see how this helps. In the picture below you can see the foam strip that runs around the aperture, behind the round vents at the bottom of the picture, where the air is actually blown into the passenger compartment. That is what is providing the airtight seal for the heater, not any silicone added to the top edge. Silicone is also nasty stuff… not nice to remove if I ever need to remove the heater, or anything else afflicted by the use of it. I’ll use silicone sparingly.

Looking at heater assembly with passenger vents still attached (and as they come, which is upside down!). The white/grey line running from left to right actually runs around the sides and bottom and provides an air seal. No need for silicone bead IMHO

Sept 9th – Fit Radiators and Oil Hoses

The fan legs had arrived by now and I had a relatively free day to see if I could fit the radiator, fan, oil radiator and associated bracketry.

First get the SV radiator extensions and metalastic bobbins on.

Radiator extensions outside the chassis again. Not a knobbly knee contest.
Seems to have a nut roaming free… need to fish that out again!
Bat wings and fan over bobbins, this time with fan legs. The dome headed bolts seemed to make sense and have no reason to think that was a bad decision as I write this later on
View from the top
Checking level. This was me being OCD… there’s quite a bit of “play” in the whole assembly and I wanted to make sure it was all true. Having the radiator wonky won’t help with air pockets in the water system later – though the rad would have to be seriously off level for that to be a big problem I think
Radiator added in front of fan
View of radiator assembly from the back. ISTM that you could think about the bat wings sitting between the SV extension brackets and the bobbins – that doesn’t work though as the fan then fouls on the ARB.
Marking out where to drill for the oil radiator bracket. You drill through both the radiator side flange and the bat wing – at least I did.
Spring centre punch has been useful throughout the build
Cleaning up the bat wing
Now it looks a bit like this
And from the side

I then had a play around test fitting the oil hoses to the engine and the oil radiator. It wasn’t until a little later that I realised the part numbers written on the hoses are actually shown on the schematic diagram of the oil cooling system in the user manual – it’s small writing but you can read the part numbers. As it happened I’d figured out which hoses go where anyway, but would have saved myself a few minutes if I’d read the manual better. Another case of RTFM.

View of oil hoses from underneath
Oil hoses going into dry sump. The hose running out of the left of frame may need some protection against rubbing on the cross member just above the label
View of the top of the engine bay with radiators and oil hoses loosely in place. Various other pipework is draped around to get an idea of where each pipe will go and and how long they need to be

That was all I had time for today… now a quick dash from Bristol to Edinburgh to deliver Harry to University.

Build Session 14 : Oil Tank, Breather Tank, Steering Column, Throttle

scuttleToday was a PTO day, for those of you that aren’t up with that vernacular, PTO is “Paid Time Off”, a holiday.

When I first ordered the kit from Williams I had planned to take a whole week off when the kit arrived. Work commitments changed waiting for the kit to arrive so I have to make do with taking the odd day here and there and doing what I can at the weekends.

Engine Mounts

I realised over night that I hadn’t actually tightened the engine mounts and painted the earth connection. In the end my earth connection to the LHS engine mount looks like this.

Chassis mount earth strap after painting

Oil Header Tank

Ok so on to the dry sump oil header tank. The tank drops fairly straightforwardly into a triangular space in front of the engine. There are then four specially formed pipes, a breather pipe from the cylinder head and then a waste pipe to a catch tank.

Oil tank in place

The manual is a little vague about the fixings for this tank but I found an M8 setscrew in misc fastener pack that would work for the top fixing. The tank seems to be a little tall for the space it occupies and so sits a few mm high from the central cruciform point that the top fixing it’s supposed to be bolted to. A few spacing washers fixes that though.

At the bottom of the tank a two holes drilled in the lower flange of the tank. I made another manual error here and didn’t read the final section on fitting the tank and missed that there are instructions to fit p-clips to the chassis rails and to secure the bottom of the tank to these p-clips through the holes in the flange. I faffed around a bit trying to figure out what to do here and eventually emailed Derek.

Email to Derek.

Derek sent pictures. Need 25mm P-clips and that I could use the P-clips from box marked starter motor. Derek said they won’t be used anywhere else.

Had I realised that the P-clips were all part of the manual instructions then I would have soldiered on assuming all the bits were in the kit. In the end I played around for too long thinking I was doing an improv. when actually all I needed to do was assume the kit contains the parts I needed. Note to self, read the manual more thoroughly before each session.

I had 3 stints at oil the tank. Faffing around with non-suppled nuts and bolts. Then realised I hadn’t read the manual and in the end I could use nuts/bolts from misc pack.

I got the tank in on third the attempt. It was the P-clips that caused all the time wastage. Firstly finding them the finding fixings (manual doesn’t say where to find any fixings) and then fitting them. They are tricky blighters to get installed. There must be a trick but I hadn’t found it. Using a pair of grips was clearly the right way to go, getting the radius of the P-clip to be formed by the cross member and the grips. I got there in the end though. I probably took more than 3 hours on the header tank today – and two of those hours were probably wasted in messing around going in the wrong direction, not reading the manual and then struggling to get the clips on.

One of the P-clips holding bottom of oil tank

I used 4 washers as spacers for the top mounting. There’s a washer and spring washer just below the setscrew head.

Oil tank top mounting with spacing washers. The black object at the bottom of the picture is the cruciform at the front of the chassis.

I could then attach the top oil pipe, that comes out of the back of the cylinder head, to the tank. It needed to be cut to length and then a retaining P-clip to be flipped to drop the pipe down to the height of the tank. There’s about 50cm of pipe that gets cut off and I saved it away in my “might be useful later on box” – note from future self, yes it was useful to connect the oil catch bottle to the oil tank.

Flipping the p-clip on the cylinder head oil breather pipe

The images Derek sent earlier about the tank mounting seem to vindicate this approach but I also went back to the pictures I took of the 420R over a Williams a few weeks ago. On their top oil pipe they have no P-clip at all near the tank.

420R engine bay picture taken at Williams. Note the poorly fixed oil breather pipe going from the rear of the cylinder head to the front under the nose cone.

Oil Catch Bottle Bracket

The manual says to attach the oil catch bottle to the chassis with rivets. That’s not a problem but I wanted to try and use the rivnuts again. So, I drilled out top bracket holes to 4mm and then drilled 6mm holes in the chassis, drilling out the rightmost rivet in the process. I could then use an m4 rivnut and attach the tank bracket. Seemed to work really well.

Rivnuts installed ready for bracket to be screwed on. The aluminium plate has a rivet on the left and then the two rivnuts I installed to its right

The bottle then slips onto the bracket. I still have to figure out how the pipework connects to the oil tank… from what I’ve seen you don’t use the supplied cap and hose.

Oil catch tank in place. Hoses not figured out yet


Now the primaries are in place we can now fit the steering column. The column is fed through the holes in the dash and rear of the scuttle, through the  top section of the pedal box and then into the engine compartment. The bottom of the steering column has a knurled section that fits into a similarly knurled universal joint. The universal joint then slots onto the steering rack.

The plan is to get the cross of the universal joint vertical/horizontal and for there to be as straight a path, for the steering column, as possible.

The first problem here was that while the steering column fits into the universal joint fine, I couldn’t get the bolt closest to the steering rack into the joint. There’s a recessed slot in the steering column that holds the bolt captive… so that even if the bolt becomes loose the steering column can’t come out of the universal joint. So I fettled (with a Dremel) the uni-joint and painted it with two coats of hammerite… that took a fair part of the afternoon in-between other jobs, two hours between coats plus final drying time.

Dremelled and painted the steering universal joint. You can see the knurling on one of the the clamp parts at the bottom of the image.

The second issue I found on the steering column was that I seemed to be missing a setscrew that is used to fix a collar around the upper and lower steering columns.

Upper and lower steering column with their clamp, but only one setscrew. Derek pointed out I have the upper plate of the clamp upside down

I emailed Derek and the missing imperial setscrew was sent out. The lower column has a half round cross section at its top. The upper steering column is hollow but has a recess in it so that when the lower column is slide into the upper column there’s a gap in the upper column that the collar can sit around. That all sounds too complex for words, so I’ll insert an image from later in the build here so you can see what’s going on.

Lower steering column (left and hollow upper steering column (right) fixed together with collar (middle). There are two screws coming from lower column and a setscrew and locking nut on top.

A quick aside on this steering column arrangement. I think this is peculiar to the quick release steering wheel setup. The upper column slipping over the lower column allows some form of collapsibility, which seems to mean that an additional crushable box in-between the steering wheel and column is not required when going through IVA if you have this quick release wheel.

Back to the build… While the universal joint was drying I could continue with the steering. I fitted the lower steering column through dash. As the column slides through the dash and pedal box it naturally wanted to sit up against the primaries. But once seated in uni-joint it was routing correctly away from primaries and doesn’t look as though it will make contact.

The upper steering column also goes in through the dashboard.

Hole in the dashboard where the polythene bush and steering column go. The white cylinder in the recess in the dashboard takes a polythene bush

There are two polythene bushes used here to provide a bearing for the steering column, one is in the engine-bay side of the scuttle and the other is on the passenger compartment side of the dash. The upper steering column goes through the bushes which keep the steering column in place at its top. The engine-bay bush is already fitted to the car, the passenger compartment one has to be fitted. I first tried to fit this upper polythene bush onto the column and then feed the column and bush through the dash. But that didn’t work well with the quick release etc. So, pulled the poly bush off the column and seated it in the dash on its own. Lots of PTFE lubricant on top both poly bushes and both rubber grommets in the pedal box and cheese wedge. The upper column then slipped through the two bushes with no problems.

Steering Wheel

The Momo steering wheel is great. Perhaps not quite as nice as some of the suede trimmed ones I’ve seen but none-the-less this wheel is nice.

However, there is a three pointed pad that is velcroed to the rest of the wheel and which covers the screws holding the wheel to the quick release mechanism…. and… as I took the pad off the rest of the wheel it was clear that only two of the three velcro pads were glued in place. One side of one of the velcro pads had come away from its glue pad.

Wheel and centre pad

B&Q and The Tip

Now… While waiting for paint to dry I could have got on with other things but I needed to go to the tip and to B&Q anyway. I wanted to get some silicone sealant as there are bloggers who have used it in various places. I could also go looking for some double sided sticky pads that I could fix the steering wheel with. Imperial drill bits were also on the list but in the end they don’t do them any more. I needed the imperial bits because I’d tried to use some of the imperial diameter rivets with a slightly oversized metric drill bit to create the rivet hole, but the rivet had pulled through the hole… I needed the right sized bits. In the end I ordered a set from Amazon.

I also made a trip to the tip to get rid of some garden waste – killing a bit of time instead of watching paint dry on the universal joint.

When I’d got back from my outing I looked at the oil tank bottom fixings again. And so after a couple more unsuccessful stints at the oil header tank the paint had dried and could fit the universal joint. I twisted the steering rack to line up better with the steering column. For best steering feel the rack spigot needs to point directly up the steering column and the uni-joint cross needs to sit vertical/horizontal when the steering is straight ahead. Torqued uni-joint up to the requisite 20Nm. It also meant I could finally tighten the bolts on the steering rack.

Fixed the Steering

Used a thick pad of double sided tape to stick the velcro back onto the wheel
Centre section now held on properly by three velcro pads

The velcro had come away from the wheel, so I scraped off the glue pad from the wheel and applied my new double sided pad to fix it. Job’s a good ‘un!

Throttle Cable

The manual says that while you have the pedal box cover off, fitting the steering column, you should fit the throttle cable and brake light connections.

The brake light connections were already on in my kit but the throttle cable needed fitting.

Lots of people have talked about he throttle cable being too long and needing to snip one end off and fit with an electrical screw terminal. More on that later.

The throttle body end of the cable went in with no trouble. The pedal end was a different matter.

The throttle pedal shaft has a slot and hole arrangement at its top. The end of the cable has a nipple with a small shaft and a rounded dome, both moulded together. The nipple is supposed to be thread through the frontmost slot of the throttle pedal shaft and into a hole.

Throttle cable nipple goes through throttle pedal shaft

The pedal shaft slot and hole are clearly meant to receive the nipple but pushing the nipple down into the pedal shaft. However, there wasn’t enough clearance for this arrangement to pivot into place.

So, initially it was out with the files. I thought there might be some burs clogging the hole. After a while of filing it was obvious that more drastic measures were needed and I got the Dremel out. I opened up the hole and this allowed the nipple to do it’s pivot thing and it was securely locked in place.

Throttle cable nipple can fit into the throttle pedal shaft once the rearmost hole is opened up

I was careful with the Dremel to make sure I didn’t open the hole out too much. This would allow the possibility of the throttle cable escaping the pedal shaft. I have it set so that its easy for me to take it out but I think highly unlikely to pop out by itself. The manual says to crimp the pedal shaft slot to stop the cable escaping, but that seems like a poor long term plan. I’ll see how the fixings stay in place over time and maybe crimp it up if its a problem.

Even though both ends of the cable were in place there was still slop in the accelerator pedal. There are three adjustment points on the assembly. There’s a threaded stop on the chassis for the upper travel of the pedal. There’s a threaded stop behind the pedal for the lower travel (pedal fully pressed) and there’s the adjustment of the cable which sits at the throttle body end.

I played around with the cable adjustment a bit but it was clearly going to take some finessing and I decided I’d leave the adjustment to another day and to therefore leave the top off the pedal box for the moment. The generally accepted solution is to bend the throttle pedal shaft to take up the slack, but I wasn’t quite ready to do this yet. I did sit in the car for the first time to test out the acc. pedal at one point… I’d been itching to do this for days but hadn’t succumbed until now.

An ill-practiced selfie of me in the car. Vroom vroom!

In the end my PTO day saw me spend an elapsed 12 hours on the car and visiting B&Q and the tip. However, totting up the actual time spent I only got 7:45 of actual build time.

And this is how it looks at the end of today…

At the end of build session 14

Build Session 13 : Exhaust Primaries, Cat and Lambda Probe

Before getting into today’s session lets have a bit of a recap on progress. Of the 90 tasks I have on the project plan, we have 36 tasks completed. And there are a few tasks on the plan that we’re not going to need to do thanks to Caterham doing them already, like weather gear and a lot of the interior trim riveting. I don’t think there’s any point in trying to work out a percentage of work done, as some tasks are trivial and some major. However, it has taken 23 elapsed days and 11 build sessions to get here so far.

I’m also noticing that I seem to be unusual in that I’m following the plan. Many other builders seem to chop around the build. Perhaps that’s because they are missing parts… which I think is more a thing of the past. Sure, there have been things missing from our kit but considering the complexity of the kit and the number of options, I’m amazed they’ve got it as sorted as they have.

On the build-order point: I’ve seen a few bloggers put the differential and prop shaft in before the engine… that seems a little nuts to me. It’s got to be more difficult to get the engine onto the end of the splined prop shaft while the engine is dangling in the engine bay. It was difficult enough to get the engine located without having to marry it up to the prop as it goes in.

On with the build…

Header Bolts and Gasket

One of the main jobs today is to get the exhaust primaries on. The exhaust ports on the head are covered with tape and with the exhaust port gasket… I’d normally be thinking “manifold gasket” but it’s really four manifolds, or primaries, but one gasket.  The manifold bolts are already in the head holding the gasket on.

Cylinder head with protective tape, gasket and bolts

Perhaps I was being a bit OCD at this point but I didn’t know whether the manifold bolts were going to be different lengths so I numbered them just in case I got them mixed up. Turns out they are all the same length.

The exhaust gasket is only loosely attached so drops off. However, there is masking tape covering the exhaust ports which peeled off but left tears and residue on the cylinder head. I removed any glue residue with petrol.

Cleaning off protective tape glue residue with petrol

At around this point the manual tells you to make sure there is protection around the hole where the primaries exit the engine bay. Cue more cardboard and masking tape.

More cardboard added, around the hole in the bodywork where the primaries exit the engine bay

At this point I think I got a bit confused about the numbering that the manual talked about for the primaries. I had to work out which primary goes where… however, it’s totally obvious so not a problem to work out. If nothing else it’s obvious from the pattern of the manifolds and how they make up a jigsaw puzzle to cover the exhaust ports – each primaries’ manifold is a different shape. I numbered the primaries with my green paint pen at this point just so I didn’t have to go back and work this out again.

Next up you feed the primaries either in through the bodywork or out from within the engine bay. I can see how it would be trickier if the steering column is already fitted. I was following the my project plan which is a copy of the order recommended in the manual and so I hadn’t got to the steering column install yet. The order recommended in the manual is working out well at the moment.

I then did up the manifold bolts loosely…

Primaries in place

… and made sure the 4:1 end of the cat would fit over the ends of the primaries. Then I tightened up and then torqued the manifold bolts. A couple of them are tricky to get a socket with extension bar onto, you need a wobble joint on the socket extension bar and of course that affects the torque. I tried to factor that in when torquing everything up.

I’m really careful when tightening up cylinder head bolts these days. My first experience of replacing a cast iron manifold on a Triumph Dolomite when I was 15 (35 years ago) taught me to be careful and tighten the bolts up from the centre outwards. I broke two manifolds in 24 hours much to my fathers amusement on the first breakage, and consternation on the second, when he had to go back to a local welder and explain I’d “done it again”.

Of course this head is Aluminium (not Aluminum… that’s not an element it’s a spelling mistake 😀) and I’ve also had my fair share of having to helicoil cylinder head bolts on old engines with stripped threads. So I was taking it carefully here!

The four primaries create a 2×2 grid of pipes to attach the catalytic converter to.

2×2 grid of primaries ready to be hooked up to the cat

As the primaries went into the cat I could have used some exhaust sealant at this point, we’ll see if they leak or not later on. It took a fair amount of force to get the primaries into the cat. I resorted to the rubber persuader towards the end of the process but I’m not convinced I got them all the way home. Again, time will tell. Perhaps if I’d got them on further then the next step would have been easier…

The Dreaded Cat Springs

The task here is to attach two reverse springs to keep the primaries attached to the catalytic converters. They’re called reverse springs because when you compress the spring the hooks at the end expand, allowing you to hook the spring assembly over something that needs pulling together.

It wasn’t a difficult job, just time consuming. The trick seems to be to pull the springs into compression with cable ties. As the springs compress they push the arms of the reverse spring assembly outwards, making them wider. This allows them to “slip” over the hooks on the cat and the primaries and then you can release the spring and the assembly tightens.

I used a vice to compress the springs and then two cable ties a right angles across the axis of the spring to get enough even compression.

Compressing reverse spring in vice. At this point I thought I only needed one cable tie.

As I said, I think I may not have the primaries fully home in their receivers. I had to compress the reverse springs to their fullest extent and then persuade them onto their hooks with needle nose pliers. As you can see the spring has a long way to go to reach over the hooks on the cat and primaries

reverse spring needs to go over cat and primaries’ hook

I got there in the end but it took longer than I was hoping.

Exhausted! Yeh… I know… its not funny and its not clever!

The manual goes on to tell you how to install the rest of the exhaust system but recommends you leave it untill later…. I’m leaving it ’till later.

Lambda Alpha Mu Beta Delta Alpha

Now we had the catalytic converter attached to the primaries it was time to fix the lambda probe, a Rover part.

Rover lambda probe

In principle the probe is a simple job. Screw in the probe, route the cabling and plug it in. The picture in the manual shows the lambda probe’s connection happening on the rail running perpendicular to the length of the car at the end of the driver’s footwell. However, that rail is really exposed to the elements and stuff that’s going to get kicked up underneath the car. Doesn’t seem like a great place to put it. The cable that’s supplied with the lambda probe is also really too long for the connection to make sense there either.

I’d taken pictures of this part of the install when I visited Williams and looked at their factory built 420R. They had run the cable from the cat along the driver’s footwell rail but had made the final connection to the loom inside the engine bay. This makes more sense but I didn’t have a picture of exactly how that connection was made.

Those Williams pictures also showed how the lambda cable gets run along the rail and three rivets used to fix the cable to the chassis rail. Our car came with silver foil tape covering this rail and I wasn’t sure I could rivet into the rail without making a mess.

I was also keen to have some way of being able to replace this cable if I ever get lambda sensor problems. It’s not unknown for lambda sensors to go faulty and I would be drilling out rivets if I went this route.

So… rivnuts. I’d not hear of rivnuts before reading the various 7 blogs. For this like me who have not come across them, they are a threaded blind rivet. You drill a regular (though larger) hole, place the rivnut in and pull a threaded mandrel back out creating the bulge behind the original hole. You’re left with a threaded blind rivet.

Rivnut tool
From left to right, uncompressed M3 rivnut, compressed rivnut with M3 bolt, M3 mandrel

Perhaps this was a bit of a mistake in the end… rivnuts need larger holes than a standard blind rivet and I didn’t want to go crazy with the size of the hole I needed to put into the chassis. So, I went with M3 rivnuts and associated 4mm holes… hmmm… the problem with this size of rivnut is that you tend to pull the mandrel out of the rivnut as you form the fixing in the hole, which of course means you’ve stripped the thread in the rivnut. I’ve tried this a few times now and M3 is just a bit too small. If you couple that problem with the limited space I was trying to work in along the chassis rail… then I really struggled to get 2 of the 3 rivnuts in place securely.

Since working on this part of the build I’ve bought a few more M3 rivnuts from different brands. I theorised that the rivnut walls are too thick for the thread load that M3 can support making the fixing. I thought I might just have a thick brand or batch. However, they all seem to be the same that I bought and they all strip the thread with the mandrel.

Back to the present… I’d also bought some screw mounted cable tie fixings. So the plan is 3 lots of rivnut, screw mounted cable tie fixing and cable tie.

Rivnut, cable tie and holder assembly (left), components laid our (right)

The next problem was that the screw mounted cable tie fixings needed to be rotated into position so that the cable tie ran up/down and not left/right… the lambda probe cable runs left to right on the chassis rail so the cable tie needs to lie top to bottom… but the cable tie can’t be inserted once the cable tie holder is in its final top/bottom orientation – it fouls on the chassis rail. So I had to screw the cable tie holder in so it was almost tight on the rivnut… then put the cable tie in left/right and twist the holder an cable tie through 90 degrees to run the cable tie up/down. Then the lambda cable can run left/right and I could tighten up the cable tie around the cable. Hopefully the image below shows this problem.

Cable tie holder and cable tie in place. Foil all messed up 🙁

[Note from my future self (time travel is possible in blogs apparently): I’ve done a lot more rivnutting since doing the lambda probe and I’m going to revisit these fixing before the project is complete]

Three cables ties and holders keeping the lambda probe cable in place on the driver’s side footwell chassis rail. You can see the connector for the cable and loom tied on top of the chassis rail in the top right of the image.

I also ended up messing up the aluminium foil on the chassis rail quite a bit. I decided I’d done a good as I could at this point and that I’d either come back and  redo the whole arrangement or just tidy up the Aluminium foil with some Aluminium tape I’d got in my tape box.

The car comes with the loom side of this lambda probe connection cable tied to the chassis. There’s also quite a lot of cable on this loom side of things.

Initially I thought I was going to have too much cable to be able to make a tidy connection, but eventually I found a way of doubling back all the cabling to make a tidy connection and routing of the cable.

Lambda probe connected to the loom and connector sat on engine bay chassis rail. The lambda probe cable comes into the connector at the bottom of this picture. Loom connection at the top. The silver padding in the bottom right of the image is the end of the driver’s footwell.

In the end the fixings I put in the chassis are not ideal but the job is done and I can move on.

The car looks great with the polished primaries and catalytic converter in place…

Primaries and Cat now installed

Build Session 12 : Delivery, Gearbox Move and Engine Bay First Fix

Saturday morning and a chance to get a few hours in on the car. I’d not really had a chance to do anything since putting the engine in last Monday. I had managed to sneak into the garage late one night and fitted the gearstick and gear knob, but that’s more of a treat than a task.

Gearstick has a ball towards the bottom that locates into a notched recess
The gear knob is a special “R” version

Wing Protectors Delivery

We also got a delivery during the week… I’d been rummaging through the various cardboard boxes that we now have left to empty and I couldn’t find the rear wing protectors. A quick email to Derek and the protectors arrived mid-week.

Carbon fibre rear wing protectors and fixing pack arrived

Engine and Gearbox Revisit

Back to Saturday though… Just as I got started I had a helper show up. A family friend had been keen to come and help and he showed up this morning to lend a hand – thanks Jack.

The closeness of the gearbox to the left hand side transmission tunnel wall had been bugging me. I had had a couple of goes at increasing the gap between LHS of transmission tunnel chassis and the gearbox but with not effect. Surely it couldn’t be as close as it had ended up with.

So… Jack and I got the jack out (sorry couldn’t refuse that one) to give it all a tweak. We lifted up the engine and gearbox again with our trolley jack and undid the gearbox and engine mounts. We then spent a good 45 minutes trying with screwdrivers and a crow-bar to see if we could move the gearbox over – no joy, again!

Whatever we did it resolutely stayed put. I tried “persuading” the engine mounts with a rubber mallet, crow-bars between gearbox and chassis and all sorts of jiggling of the jacks (both of them) and bolts.

The gap between gearbox and chassis remained the same at around 1mm.

Gap between chassis and gearbox resolutely remained the same at around 1mm

This is going to have to stay like this until at least the PBC.

Later that day I had a visit form Lotus Pete, from two doors down. He had a look at the gap and pronounced: “it is a bit tight… but you’ll never move the engine over on any play in the mountings. It therefore shouldn’t move too much under cornering”. And.. subsequently in an email exchange with Derek Howlett he confirmed “they are all close”. That’s enough for me… we’ll see what Williams say.


Jack and I then turned our attention to the engine and gearbox electrics…

The gearbox reversing switch was first. There’s a set of plugs located in the transmission tunnel that you have to connect to the reversing switch on the gearbox. There are actually two sets of connections on the gearbox, the front most are the reverse switch, the rearmost are a neutral selection switch (telling you when you’re in neutral) – not used on Caterhams.

It was a bit of a fiddle getting our fingers to the plugs down the transmission tunnel but Jack got there in the end.

Chassis loom connects to the reverse switch wiring (green wires). The blue wires at the bottom of the picture are a “neutral” selected switch (picture taken looking down the transmission tunnel from inside the passenger compartment looking down towards the engine bay)

[ Since completing my build I’ve seen comments and talked to a couple of new builders that didn’t have the same connectors as I had for the reverse switch – it was a simple push fit for me. One builder just had to jam two spades, with no shroud, into the female side of the connection. As of 2018-07 is now seems that Caterham ship a stub lead in with the engine fittings to go from spade to bullet connections… The image below is from Will Baverstock’s 270R build…

New 2018 Stub Lead for Reverse Light Switch. The top lead is removed and then the bottom lead replaces it.


There’s a grommet that needs fitting to the driver’s side footwell, and another one for the passenger side, but we didn’t fit this passenger side one at the moment in case we need to get to the gearbox filling plug – its conveniently set behind a hole in the passenger side transmission tunnel wall.

Grommet in driver’s side transmission tunnel wall

Next up is the main ECU-to-loom plug and socket. This is a large grey and red connector that sits forward and below the battery. The connection is simply made with a push and lever to retain the connection.

Multi-pin ECU to Loom Connector

What’s not obvious is where this connector is going to be sited when done. I’ve seen various pictures of self-build and Catherham built Sevens and they all seem to have this connector floating down below the battery. It’s going to need to be cable tied to something to stop it rattling around but its not obvious how it should be orientated and what it should be tied to.

Power to the Starter Motor

Next we connected the main 12v lead to the starter motor. The manual tells you to connect the battery at this point but I wasn’t in need of any power to anywhere so decided to leave the battery disconnected. I was also unsure about where to locate the engine earth connections and wasn’t ready to connect them either so the battery was going to stay detached for the moment. More to come on earthing in a later post.

Back to the 12v connections… I ordered the car with the 12v cutoff switch.

I’d read lots of forum posts and blogs where people have had problems with laying cars up over winter and finding that they car’s battery was flat in the spring. I’m hoping not to lay the car up for too long but that’s just the plan, I can well see that my desire to drive in all weathers might wane after a few years/months/weeks (delete as appropriate).

Anyway, we have two cables as part of the cutoff switch, helpfully labelled as S (starter) and B (battery).

S for Starter, B for Battery

The S lead goes to the starter assembly as below…

12v lead connected to the starter motor

The manual talks about connecting brown wires to the starter and alternator. As far as I can tell this is all connected on our car. It’s just the 12v lead to the starter motor that’s required now. You can see the brown lead coming off the same terminal as the red 12v lead and then that goes to the alternator already.

Fuel Pipe

Fuel Pipe next… this is a special locking connector. Apparently you need a special tool to take it off once it’s connected, so we made sure we weren’t impinging on any other wires as we slid the fuel pipe connector home. I’m not sure what’s so special about a tool that’s needed to take this plug off, that’ll require some research at a later date.

Fuel pipe connector is a simple push fit but needs a special tool to take it off again.

Clutch Hose Banjo

On to some hydraulics now. The braided hydraulic clutch hose uses a banjo connector to be attached to the clutch reservoir. There’s nothing much to get wrong here, however, the manual calls for protective shroud to be used on the clutch hose and I haven’t figured out the best way to do this – I suspect it will be cutoff section from the water expansion bottle 5/16″ hose (that’s what I’ve seen on other builds). I’ll post pictures of that in an engine tidy-up post letter in the build.

Clutch hose and banjo connector

I’ve left all of the cables and pipes loose in the engine bay at the moment, and intend to leave them loose going forwards, until the last minute. It seems that there are plenty of options for tying things down in the engine bay and for routing cables and pipes. I don’t want to spend time tying something down only to find it fouls something else later or there’s a better option that comes to light. So, there’ll be a task to tidy up the engine bay in a later session.