1970 911t 2.2

[Kamalea]

i am rebuilding an engine i recently purchased for my 1970 911T , 2.2 .
i had the casing line bored at Competition Engineering Inc in California which will require the installation of 1.0 mm shim to compensate for the casing surface machining.
Also I had the Cylinder heads restored and machined to the tune of another 1.0 mm shim requirement.
both machine shops indicated that it is not for certain that I need the relevant 1.0mm to compensate for their work but I might need to do few trial and error measurements with Play doh to figure out the exact total size of the required shims.
I have purchased 0.25mm, 0.50mm and 1.0mm shims.

can anyone please tell me how many shims is acceptable or allowed? as i may need 1.75mm total. (it means one of each of the shims I bought. worst case scenario) Please help. Thanks

[doswald]

I’m not an expert by any means, but I highly recommend the series of videos on YouTube by Kurt at Partsklassic in which he demonstrates all of the various measurements and calculations to determine compression ratio. You can then determine which shims are needed.

Where did you find the shims?

Good luck!

DHO

[Kamalea]

Thank you..... I watch Kurt's videos all the time. he is good source of info.
I don't. have the tools or knowledge to go through all the calculations he does.
many thanks for your reply.

[TwoBluPorsches]

I believe that after you get the shim height figured out, you’ll need to figure out if the cam chain housings will need adjustment.

I’ve got limited experience and can’t say how much case work results in a requirement to change to housings (AKA material removed).

It’s just another thing you’ll have to look into.

My datapoint is that I had a 7R case line bored to standard and the cylinder surface and the housings still fit.
Competition Eng did the work on my case
Walt might be able to let you know if he’s taken off enough material that the housing should be machined


Sent from a device using an app.

[mcaterino]

I did a similar rebuild on a mag 1970 case, and also had my head and case work done by Competition Engineering. So you may find my engine rebuild thread
(Caterino's 1970 engine rebuild) useful. I considered 1.75mm, but ended up going with 1.5mm of cylinder base shims. But the thread will explain how I ended up at that solution. I can report that the car ran great for the few years that I kept it. Sadly I had to part with it a few years back.

Good luck!
Mike C.