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EPorsche · 10-23-2005, 04:11 PM

I just finish doing the valve/piston clearance check and the news is not good. What could have cause the clearances to be to tight. The number one piston/valve is worse than number four. The crank was polished, the heads rebuilt with new guides/stems and one intake valve that was out of tolerance. I have what is I think RS pistons and 143/144 camshafts.

Eagledriver · 10-23-2005, 04:46 PM

I assume those cam numbers are "S" cams. I think this is common for that combination. I had to have my valve pockets deepened about .030 inches on the intake and .020 on the exhaust with the same setup you have.

If you look in the original factory manuals they allow a very tight tolerance (I think it was 1mm). I think I could have achieved this tolerance with slightly retarding the cams and using the thicker base shims. I wasn't comfortable with that so I did the above cutting. I suspect the engines from the factory had the very tight tolerances that you are seeing.

Ted Robinson at German Precision can cut the pockets deeper for you. There is lots of metal on the bottom of those pistons to accomidate the cutting.

-Andy

EPorsche · 10-23-2005, 04:53 PM

Thanks,
I agree because #4 I can get down to 1mm. I think you are right about have 1.5 to 2mm of material removed. I just that I had very little machine work done.

camgrinder · 10-23-2005, 07:15 PM

The 143/144 are Cis S cams. What are you setting them at?

EPorsche · 10-23-2005, 07:23 PM

I setting them at .47 intake valve over lap. I'm sure if I adjusted valves 1 and 4 at .004 TDC that I could turn the crankshaft 720 degrees. But what about thepiston/valve clearance?

Wayne 962 · Wayne 962's Garage

Whoa, there's not enough information here to give an opinion.

What specifically are your camshafts? CIS cams and RS pistons are not really compatible.

What are the specs on this motor, what are you trying to build?

-Wayne

EPorsche · 10-24-2005, 04:51 PM

Wayne,
Glad to here from you. I bought the car about a year ago and it ran fine but had some oil leaks that got worst over time. I figure I would rebuild it to "clear up the leaks". When I open pulled the cylinders the above picture is what I found. I'm just rebuilding it the way it is. The engine number is 6551182. Do you have any suggestions?