MKB 752 E Update

[bobwhittaker]

HIGHTORQUE STARTER :- Sounds to be the way forward and will build into the budget after the paint,that should be complete by Saturday 6th April going off an update today .Regards other suggestions on cold cranking I have already ensured alternator / battery / earth and supply leads are upto the job.Ignition might be a touch advanced but no obvious "pinking" when driving.The cylinder head I am using is stamped on top face 0.0625 and also 18.5 and it as also been chambered and ported.Albeit it is something of an unknown quantity,comparison with other heads I have got it has been skimmed by 0.0625 and I presume the chambers have all been equalised at 18.5 cc thus CR is high and it has with standard size valves, it is running without vacuum A R and strobe at 900rpm shows 15 advance, obviously moving up as the revs increase,it has 40 DCOE and only 30mm chokes . If I had been looking for big numbers in the HP game I would have installed something that started with with Hya and ended in busa rather than wringing the neck of an "A" series.
This car is chassis number 123 of the orignal 138 manufactured by Westfield in approx 1986 and I bought it unbuilt some 2 1/2 years ago ,the body mouldings are nowhere as crisp and finished as the current offerings and I have not set out to create a 2013 toolroom copy of the Lotus XI but more something that has a period look, drive and feel of the original.
When painted and after final build I will try and upload some photos, feel free to PM or visit. Cheers BOB WHITTAKER

[Westfield 129]

If you have a head with the chambers of only 18.5, you have VERY high compression, indeed. My new engine has 20.5 cc chambers, and I just added a .060 shimed head gasket (from Cometic) to drop the compression down to about 10.6:1 so it would run on 91 octane. It is important to know what pistons you have, and the dish to calculate the compression ratio. You might take a good look at the valve gear to make sure that the valve springs are not binding, and the push rods are not bending. You might need to shim the valve gear.

You should set your timing to 10ºBTDC. If you have a dial back light, you can set this accurately, then check the maximum advance at about 32~34º BTDC at around 4000 RPM. If you have as much advance as you are using now, you risk blowing the top ring land off the stock pistons. Drop the timing back to be safe.

[bobwhittaker]

WESTFIELD 129 :- Have only just picked up your comments regards ignition timing and chamber volume etc. They all make sense and it my intention to act on them. Cheers Bob Whittaker

[jonclancy]

Just to add:

My car uses a bolt through the chassis rail behind the driver's seat for earth. Over time, corrosion caused resistance and slow cranking. I replaced the bolt with an M6, stainless rivnut and new A2 nyloc, bolt and star/plain washers.

Cranks over as fast as you like now. Might not apply to your car, Bob, but I think it's worth a check over for everyone - if only to prevent problems down the line.

[Westfield 129]

'Just had the same problem on my new car. The factory managed to forget the ground stud in the rear, for the battery negative cable.

I installed an insert into the chassis, and used a nice, stainless bolt. Well, it looked quite solid, and very clean.

All was well until it was not, and it would not start. seeing that I had a clean, solid connection at the rear, I started to wring out the electrical system, which I had designed and built myself.

In the end, it turned out to be the negative cable, as the insert I had installed in the frame was not tight enough. Once I tightened the insert, I again had voltage at the front of the car.

Battery cables, grounds and alternators can be troublesome and occasionally, produce difficult to diagnose problems. Another thing to always check, even if new, is the battery. An intermittent short in a cell can drive the charging system crazy, and make for all sorts of unusual starting problems, and the occasional loss of all power.

[bobwhittaker]

MKB 752 E Had the car on the rolling road at Minisport in Padiham ( Only about 10 miles from me ) If you go onto www.facebook.com/minisportltd and scroll through there are two photographs of the car.Where the comment "Factory Built" has come from I don't know ! The build was my work and not Westfield. BOB

[Westfield 129]

If you go the rouet of installing a rivnut in the chassis to ground your battery, make sure that the rivnut is TIGHT, and installed into clean metal.

I had the rivnut for the battery ground get very slightly loose, and it made the diagnosis of the voltage loss a bit difficult. Stainless steel is not really necessary. Having a good, tight rivnut installation, with a star washer behind your battery connection is the key .

Welding a threaded stud onto the frame is best. The factory used to do that (they eliminated the stud in 2010).

[bobwhittaker]

Clutch Release Bearing At build I fitted a new three piece clutch , all standard items as the engine is only mildy uprated . After about 1800 miles the release bearing (Carbon Faced) had gradualy disintegrated leaving metal to metal contact , there were no funny noises .This resulted in the release bearing holder gripping the thrust face on the pressure plate when the clutch was depressed and stalling the engine . I have since replaced all three clutch components , again with standard items and have presently done a further 1400 miles . Unfortunately things don't feel 100% and I think the problem may well be about to occour again . At build I used new master and slave cylinders and at each fit I was confident I had the corect clearances at pedal and cylinders . I have now purchased a Peter May Engineering roller release bearing conversion kit and will fit this in the next couple of weeks . Does anyone have any comments or suggestions . I have been driving for 53 years and never previously had to replace these items , let alone twice in 3500 miles and to the best of my knowledge this problem is not caused by me " Riding" the clutch .
Cheers Bob Whittaker

[Westfield 129]

The graphite bearing should have lasted longer. I never wore one out when I was driving new Sprites in high school. Usually, the clutch was gone about the same time as the bearing.

However, they are not known for lasting for a very long time. Perhaps there was an assembly problem, or somebody has their foot on the clutch pedal during normal driving, which wears out the graphite release bearing quite quickly.

[erictharg]

I also still use the stock carbon release bearing with no problems. I'm mindful that it doesn't like being held down for too long so the longest it is used is when that 5 second board goes up at the start of a race!

I'd check you have the correct diameter master and slave cylinders.

I managed to make and fit a very narrow clutch footrest (maybe 1/2 inch wide) that allows me to just sit the edge of my left shoe off the pedal as it is easy to let your foot sit on the pedal itself otherwise.