hi im going to check my compression tomorow night as my car blows smoke on start-up etc and is feeling tired. what should it be?

180PSI is optimal, anything under 140ish is bad, and having a huge range of compression across the cylinders is bad too, - my old motor was between 145 and 180PSI,

does it blow smoke if you let it idle for a bit then boot it?if so thems valve stem seals

Do compression check on all cylinders. To test make sure someone is holding WOT while cranking for 3 revolutions. Mark 1st rev reading then total reading. Compare all cylinders. If more than 10psi difference from highest to lowest your engine fails to meet specs. If lower than 146psi that also fails specs. If you have two adjacent cylinders that are low this indicates head gasket failure. If you have a low reading place 1 tablespoon of oil into the bore. Repeat test on that cylinder. If reading comes good then bad rings. If still low it is either valve stem seals or a burnt valve.

Make sure test is done on warm engine.

You could then do a dynamic compression check to look for other problems, here http://www.imperialclub.com/Repair/Engine/dynamic.htm



cheers
Scott

thankyou heaps for that very usuful healp guys. so i disconnect the gas (straight gas) and get a mate to hold the throttle open all the way. now i turn the key and see wot heading i get? is that about it?

That is about it. But take out all the plugs so the engine can spin up nice and quick.