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MBradbury MBradbury is offline
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Join Date: Jan 2001
Location: Troy, Michigan, USA
Posts: 62
Andial's response

Hi again

I promised I would contact Andial and then post their response / advice on this matter, and here it is...

Firstly, I have attached an updated diagram showing more detail and extra measurements. One important additional measurement taken is that between the head and the barrel cooling fins. With the heads and cam towers in situ, I took a measurement of 0.33mm (0.013") using feeler gauges. This measurement is important, because it turns out to be less than the thickness of the sealing ring. If I were to rebuild without the sealing ring, then the head would bottom-out on the top of the cooling fins before making a seal on the proper mating surfaces. See diagram below.



Armed with the extra measurements, I contacted Peter at Andial and he explained that the set-up as machined would require the sealing ring. I also described an out-of-center cam position with respect to the chain box, and he advised there was something definitely wrong with my shimming. Referring to the diagram, Peter explained that I should be aiming for a meaurement of between 0.8mm and 1.2mm with 1.0mm being the optimum for DIM "Z". This would allow me to reduce the shimms underneath the barrels by a full 0.75mm from the current build state. This would result in the target dimensions listed in the critical dimensions table on the diagram. This would also help bring the cams back into the center of the chain box opening.

I also asked whether the steel sealing ring protuding into the combusion chamber would cause any interference or pre-detonation problems? The answer was no. Andial have built quite a few of these engines and they have never experienced any problems of that nature.

In one respect, Peter's answers give me some comfort. By applying these changes, I can redress the off-center cam issue. However, that target clearance of 0.5mm (0.02") for DIM "Y" looks pretty close. In the end I have to listen to Andial because they sourced the pistons and handled the machining of the heads, etc. Not to forget that Andial have an excellent reputation, their experience is race-bred and light-years ahead of mine.

The down side to this is that I now have to dissassemble some of my work, but there are some short cuts I can take like unbolting the heads and cam towers as one, and removing the cylinder barrels and pistons intact so I can fit the correct shims.

So there you have it. Thanks for listening.

Regards
Mark
1983 SC 3.0L to 3.2L short stroke conversion
1988 Carrera to '73 RS project
Old 12-16-2003, 06:14 PM
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