Oregon OBXT Posted January 19, 2013 Share Posted January 19, 2013 What are good numbers and the best method? IIRC, for the 8.5:1 motors its 148 PSIG in the FSM but is that low, high, or avg? Is the best technique to do it on a warm engine? I ask because I had it down for a few months without running waiting to do 105k maintenance. When doing the plugs I only saw 130, but it was +/- 1 across all 4. Again, that was with not running for 45-60 days and checked cold. Link to comment Share on other sites More sharing options...
HAMMER DOWN Posted January 20, 2013 Share Posted January 20, 2013 Compression check, spec, are 141psi to 171psi, at 350 RPM's with no greater then 7 psi between cylinders. Bring motor to opt. temp. Pull fuel pump fuse & let motor stall. TB must be at WOT when cranking motor. From other post, 120psi & up is good, as long as the psi between cylinders are close to each other. Mine at over 173k, 1) 145psi, 2)150psi, 3)145psi, 4)147psi. Mike Mileage:331487 Retired/Sold Link to comment Share on other sites More sharing options...
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