[Trak Ratt]

Thanks for resizing! Car is looking good!

There are formulas for figuring what the cranking pressure should be. But just for conversation sake figure something between 15 and 20 times the compression ratio. So 200 would seem high unless your compression ratio is well above 10:1 and/or rings and valves are in perfect condition.

The high numbers are prolly form excessive carbon build up inside the engine on pistons, valves and heads. Good news is that there is very little dif between all the holes.

Getting your carbs adjusted may eventually burn off much of that carbon. Though a top end teardown and R&R would prolly be beneficial. But for now don’t go cheap on gas cause excess carbon can create hot spots and cause pre-ignition even with high octane fuel.

[Dan M2]

UPDATED

Well after cleaning up the engine and tightening all loose head studs, I ran it and found only one oil leak at the rear main seal. Unfortunately it was a very big leak. So after talking with my helper (who is much more knowledgeable than me on 911's) we decided to drop the engine and go for a complete tear down.

We finished the disassembly today and were very pleased to not find a lot of broken bits or tired engine parts. In fact it came with 90mm Mahle P's&C's and a lightened flywheel. The engine does not show much wear at all in fact the cylinders look almost new! I need help ID'ing the pistons though. There also wasn't much carbon build up and the one cylinder with the lower compression (175) had a broken head ring seal.
It does have the original sized valves which seems a bit too small for 90mm cyl's.

Also will need to figure out how to lower the compression. I don't see the need for 200psi.

Lots of pics attached.

[Dr K]

Wow! I realize one cylinder was leaky, but can't you replace the RMS by just splitting the engine from the transmission (i.e. clutch job)? Good luck getting it back together in a reasonable time period (although I bet it will be great once done). How do you determine the appropriate valve size for P&Cs, and how do you lower compression without changing P&Cs?

[Dan M2]

I should add that it wasn't running perfectly and we had no idea what the condition of the engine really was. So since this was purchased as a project, we decided to go ahead and do a tear down so I can be sure of the condition of the engine. That way I know exactly what I'm up against. Plus I can do all the other fun things like suspension work, painting, carbs, etc I still have my 1970 for driving while this is being worked on.

[NoPaint]

So I guess the engine can go back together with just a couple new seals?

You should send off the carburetors to bieker performance and have them line bore and rebuild them. Then you will have new Webers.

[Dan M2]

New seals and bearings and few new rockers and shafts (three had scarring on the shafts). I am also considering different heads to get larger valves. Any thoughts?

The webers were supposedly rebuilt not too long ago so I will tear them down to check.

[berettafan]

Suggest Performance Oriented as a quicker, cheaper alternative to Beiker.

You should CLEAN the carbs regardless but the main 'rebuild' issue is the throttle shafts. Wiggle them front and rear to see if they are kashputzed.

[Dr K]

Originally Posted by Dan M2

New seals and bearings and few new rockers and shafts (three had scarring on the shafts).

Can you post a photo showing the scarring on the shafts? How bad requires replacement?

[Dan M2]

I'll get some pics this weekend. The scarring is very obvious and makes it tougher to get the shafts out. They are not too expensive so worthwhile to replace now.

[MikeDL]

It might just be the picture, but the timing chain looks like it is stretched.