Engine Breather

Managed to get out in the car over the Christmas break, I was keen to see how my PCV valve worked - I was looking to see how much crankcase depression I was getting in various engine conditions - my measurement method was a digital manometer hooked up to my dipstick tube. Didn't get very far before I realised my first simple in-line valve was giving me too much depression, it wasn't able to control the pressure. The downside of this is that in extreme overrun I could potentially suck the oil into the intakes.

Time for Plan B, I had picked up a diaphragm type PCV valve, only problem was finding somewhere to fit it, no room on top of the intake manifolds.

After some pondering, decided to use my redundant distributor mounting, This needed a bit of machining to make it suitable, I also added a fixing point to hold the valve in place.

Not sure where I originally picked up this valve.

The valve pushes into the modified distributor housing and is held in with a small cap head bolt.

Fits quite neatly on the side of the block

Plumbed into the intakes via some 1/2" tubing pressed into the end of the manifolds.

Checked everything was fitted ok and started the engine, my pressure gauge was showing a 15 mbar depression at idle. Took it out for a drive, subjecting it to various operating conditions, the valve seemed to pretty much maintain a constant 15 mbar depression +/- 10 mbar. The original engine breather is now the fresh air into the engine crankcase and is fitted with a small restrictor to create the depression. With no restrictor it would be like having an air leak post throttle in the intake system.

Didn't get much else done, really need to trial fit my front upper wishbones - once I know they fit of I can get on and make another set with the thicker wall tubing and then ream the internal bores to the correct size.

Trunnionless Link and Friends

Well, recently sold an injection kit so this has allowed me to spend a bit more on my car, collected the parts this week. Caterham style vertical links that will fit into spherical bearings in yet to be fabricated lower arms.


Alloy hubs with larger stub axle and improved bearings.

New 10" vented discs

And a very nice pair of AP Racing calipers, couldn't believe how light these calipers are, a friend has promised to get me a set of decent pads, they should arrive over Christmas.

No immediate plans to fit them yet, need to get the top and bottom arms fabricated first, also got another couple of engine related bits to finish off over Christmas so I've got to keep it mobile.

Top Arm Update

First pair of top arms have been welded, not bad, they have twisted very slightly and sprung in about 20 thou. The tube for the top ball joint has also distorted slightly making the adjusters a tight fit. I expected to have to make a couple of tweaks to perfect the design, this first set will be used to check for clearance issues with the front upright and to make sure I can get enough camber adjustment with no lower shims fitted.

To address some of the issues, the next arms will be made using the jig removed from its back plate so that a number of tack welds can be put in place on both sides to prevent distortion (springing). I'm also going to use slightly thicker tubing and then ream to the correct size.

Front End Modifications

I've decide a while ago that I was going to convert the front uprights to Canley Classics / Caterham front uprights, primarily for the stronger stub axle as well as doing away with the lower trunnion. I had a stub shaft fail on the motorway a couple of years ago, initially thought it was a wheel bearing until I stripped it all down and found the shaft had broken at the start of the threads.

Anyway, that started me thinking about the front end, as I use quite a large wheel and tyre, I cant lower the front end too much as I end up with contact between the tyre and arch, while looking at various kit car set ups I have decided to fabricate my own adjustable top arms and do away with the shims on the lower arms. Hopefully this will pull the top of the wheel in a little more and give me some more tyre / arch clearance. If I need more I will fabricate lower arms that are slightly shorter and adjust the tops to compensate.

I have borrowed a home made tube notcher to get the right angle and profile

This made light work of cutting the tubes

As a couple of friends have shown interest I decide to knock up a jig to aid with the fabrication.

Just need to find a good local tig welder

Knocked up a couple of adjusters that will allow me to adjust the camber without having to remove the top ball joint.

I will hopefully get these welded together in the next week and then I can make sure they fit ok. I have used 25mm x 2mm wall thickness for the bush holders, 20mm x 2mm for the rest, all seamless tubing.

Got some drawings ready for the bottom arm, just need to see what effect the top one has before I make anymore jigs. The lower arm will be made to hold a spherical bearing.

Oil Leaks

Following the 10CR I developed several oil leaks, front seal, head gasket (push rod side) and rocker cover, all fairly standard but the strange thing was my engine had always been fairly leak free.

In a flash of inspiration sat on the front wheel staring at the engine drinking a cuppa, It suddenly dawned on me that I had modified my air intake system and that maybe it was having more of an effect than I had realised.

I connected a pressure gauge up to the dipstick tube and started the engine. Sure enough a small vacuum as expected as my breather system is plumed into my intake plenum upstream of the throttle bodies.

Took it out for a drive around town, still the same, slight depression on the engine. Found a nice quite road and increased the speed, at around 50 mph light throttle my gauge started to show a positive pressure in the crankcase, not good.

I pulled over and connected the pressure gauge directly to the intake plenum upstream of the throttle bodies in place of the engine breather and went for another drive, what I found was quite interesting, when travelling over 50 mph on light to half throttle I was registering a positive pressure in the intake system, good for performance bad for my breather system. Bearing in mind that on the 10CR (while on the autobahn), we could easily sit at 110+ mph on very light throttle, who knows how much pressure my crankcase was seeing, no wonder it developed oil leaks.

To sort the cause of the leaks I have decide to connect my breather system to the engine side of the throttle bodies and used a PCV valve to make sure it doesn't suck my oil out. I have cleaned up the engine bay and now await suitable weather to take it out for a run.

Mazda MX5 Seats

This post is in response to a recent topic on the Club Triumph Forum, It does not give all the details but highlights the main modifications.

One of the problems I had when fitting MX5 seats into my car was getting them to sit low enough and as far rearward as possible to give me enough room. At 6'1" I need as much legroom as possible.

One of the problem area's is the rear floor pan where it flares out at the rear of the tunnel. If you mount the seats on top of this you end up with very little headroom.



To get around this problem, I fully stripped the seats so that I was left with just the seat pan and then by trial fitting, removed enough material from the pan to clear the tunnel area, make sure you leave the seat hinge area untouched. Make sure you take into account the height of the runners (if you intend fitting them). I then welded in some 20mm angle iron to give the seat pan some strength in the hinge area. I have highlighted the modified area in the following picture.




I used some aftermarket seat runners as the seats I bought didn't have any, the inner runner needs to be modified to match the seat pan. On my setup I used the original MX5 seat mounting points on the outer runner and the front fixing on the inner runner, I welded in a nut for the rear fixing on the inner runner.

To mount the seat in the car, I made up 4 lugs that allowed me to use the original mounting points in the floor, you could probably gain another 15 mm headroom if you were to mount directly to the floor, you obviously then have no adjustment.

I used Securon seat belts with short steel stalks and bolted these directly to the seat in place of the MX5 seat belt stalk. There are slight differences between the driver and passenger seat but you basically make the same modifications.

The seats are very easy to strip apart, you remove the complete backrest as one assembly leaving it fully trimmed, then remove the cover and foam from the base, its all held in place with small wire clips that can be opened up, I'm sure you can buy these new along with the correct fitting tools but I just re-used the originals.