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Discussion Starter · #1 · (Edited)
Over the years i seem to have forgotten what the cylinder compression (psi) should be on a built turbo engine. 5 years ago I've bult my engine and vaguely remember what compression I had. The engine is built with eagle rods, 8.5:1 JE pistons, and 0.060 Cometic head gasket. Initially the engine was run with zx2 intake cam and stock zx3 exhaust cam. In the last month ive switchd over to the stock zx3 intake cam and when i went to check my compression it reads 90psi across all cylinders. My timing is correct and verifying numerous times. If i remember correctly it used to be 120 psi across the board with zx2 intake cam, does 90psi sound right given the above specs?
 

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120 +/- is about right , 90 is to low , adjust your cam gears 1-2 deg at a time one can at a time and see if you cannot get it to come back up checking the compression each time , just because you have then in the TDC and the plate doesnt mean the cams are where they need to be

Tom
 

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Discussion Starter · #3 ·
Thanks Tom, that's exactly what i was questioning, those darn timing marks on the crank pulley are hard to see so i went to the wooden dowel into the spark plug hole method to achieve an absolute 0 tdc. Back to the timing marks i guess :)
 

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You should be using the pin on the crank or use a long screwdriver and get TDC

I would do what I said before and just more the cam gear one mark till you get the highest compression you can get then go back a mark , then go to a dyno and set them to where they need to be

TOM
 
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