Piston to valve cleance problem. 2.7

[Ray_G]

I have been trying to get my 2.7 put back together, I have Wayne's book and have read a lot about it on these forums.
The engine went to Ollies, they measured the case, it did not need to be align bored. They installed case savers, decked the case. (they removed .020 off the deck.) machined the spigots and did a vavle job. The best I can tell all they replaced on the heads were the guides and the exhaust vavles and seals of course. I bought an in spec set of Nikasil Mahle P&C's. The originals were Alusil Mahle's. The pistons are CIS, stock ones. I am running stock CIS cams, although they are from another engine.
The problem is that I put the .5mm base gaskets on the cylinders I get a 1.5 mm deck height. Then after assembling the engine and timing the cams I then check the piston to valve clearance. I use the turn the rocker screw method to figure them out. The worst intake clearance I get is about 1mm, most are 1.25. But the real problem is the exhaust valves, I get 1mm on the best one, most are around .5 or .75mm. I have double checked the timing, advancing the timing, retarding the timing on the cams just does not produce much of a difference, and certainly not the extra 1mm I need. I have put another set of stock pistons in the motor and reassembled it, there is not any diffferece in the deck height with them installed. If I move the cylinder heads around I get different readings. But the figures I listed above are the best I can get. If I get the worst case going I can get some exhaust valve clearances at .25mm.
I was wondering if anyone had any suggestions on how to solve this problem? Ask all the questions you want about how and what I did. I am stumped though. The way I see it if I use thicker base gaskets to solve this problem I will have to add another 1mm to the .5mm gaskets I already have and that would give me a deck height of 2.5mm. I don't have any experience with this, but I am afraid that will be too much and might cause detonation, but I don't know.
Anyway, if anyone can help I would appreciate it.
Thanks,
Ray

[Aurel]

Do you know how much was removed from the heads? Or, maybe your CIS pistons are in the wrong orientation...

Aurel

[Ray_G]

I don't know how much was removed, and I am unaware of any measurements I can take to find out. The domes are to the left as you face the engine. (Dome opposite the spark plug hole.. I do have a buddy that is rebuilding a 2.7, I may ask to borrow his heads and try them out to see if that is any help.

[Aurel]

Domes to the left is correct. Sometimes, the amount that was shaved off the heads is stamped on them. Testing with other heads is an excellent idea. It is not uncommon to have 0.02 removed from the heads too, which means you should double your base gaskets.

Aurel

[Eagledriver]

You are doing the right things. This is why it's important to measure each motor. I'd be willing to accept as little as 1mm for a street motor (factory spec for an early S motor is .8mm). If you can't get that by tweeking the timing then you'll need to do something like the shimming or have the pistons cut for clearance. The best way is to cut the pistons if they have a thick enough dome. I think the minimum you want is 5mm thick after the cut (Not sure about this number but the right number is in Bruce Anderson's book).

-Andy

[Ray_G]

Thanks Andy,
BUT, I am a dumb*****. I can't believe my problem is this simple. Some idiot (not me, I never got to drive this car, just tore it down) on a previous valve adjusting spree over tightened the nuts on the rockers sooooo tight that they stretched the threads on the adjusting screws. The studs would screw down about 1 turn past the valve adjustment position and then they FREEZE UP. I just now took the nuts off the rockers and tried to get screws out, no way. They go in about half way and stop. Which, is just about 1mm into the piston to valve clearance check. I had one valve that checked over 2mm and I never went any farther because there was no need. That is the ONLY stud I can unscrew from the rocker, it came out by hand.
As soon as I get them freed up and working smoothly I guess it is back to square one.
I figured this out because I assembled cyl 1 and 3 with all the base gaskets I had, and that gave each cylinder a 2mm gasket. I then checked the clearance after timing it up. Guess what, nothing changed, not even a little bit. WTF. I finally took a screw driver once the adjustment screw on the rocker stopped moving and pushed on the top of the valve spring (yes the valve moved too). Guess what, it went down more, lots more. Live and learn. I suppose.
Ray

[cgarr]

If stock heads they should be 84.50mm (3.3267) from the machined top (cam tower surface) to the cylinder sealing surface.