I have just finished a PPI on a red/tan 1977 308 GTB and here is what was found: -Compression between 95-110 on all cylinders, taken @ 185 degrees???!! -Cam Cover leaks -Fresh timing belt and others were aged -New Konis, struts and bushings all the way around -New tubi -All rubber lines and hoses in 7/10 condition -Drivers seatbelt not operational -Drivers seat adjustment track failed -Windshiled washers failed -Alternator 14.2v @ 68 amps -Ball joints and suspension solid -Cooling fans work and turn on at 185 degrees -No leaks from water pump -New tires and brakes -All lights work -The car started, drove and revved flawlessly hot or cold -air pump intact w/out belt -Could not determine if there were other leaks due to oil from cam covers -Body and frame straight as an arrow...no dings or dents -original paint on fair cond -interior perfect...5 yr old re-dye The other 50 or so items on the checklist turned out ok. What do you make of that compression test?? Should I make them redo it? Any other thoughts? thanks guys, David
I would retest and do a leak down but if true the motor is toast. If it has OK leak down the cam timing could be way off. I have seen that more than once.
I thought in the 8:1~9:1 CR range (and with reasonable valve overlap) the result should be more in the 140~150 psi ballpark. A little odd that they're all so evenly low-ish without it being an instrument, measurement method, or cam timing problem...
I am going to have the compression test done again this morning on the GTB. The test is being done at Park Place Motors and their mechanics are said to be rather reliable although I am curious. What pointers can I give them to get a more accurate picture of the engines compression. What temp? How should they administer the test? Throttles open, number of cranks, etc... Any tips would be GREATLY appreciated to salvage my $500.00 PPI. David
When we did mine: - 185 degree water temp - WOT (pull the fuel pump fuse) - crank unless pressure value increased no more. You can also crank a set number of times/duration. HTH Philip
If the motor is bad (which those numbers say it is), the $500 would be the least of your problems. Retest it the way Rifledriver suggested. If it comes back with the same numbers, walk away. There are nice cars out there with solid engines.
