BigWhiteGTP

Okay my bro and I just did a compression test on an old 1973 307 block in the garage on a wood stand. I know it's preferred to be turned over by crank, oil in the block, and intake and exhaust manifolds bolted and torqued down. But this was just as it sat. Here's the numbers, they are low: Driver side are all 50-60 and the passenger side, one read 70, one 30, and the two others were like 50-60. Valve lash needs to be corrected as well. But this was all turned over by hand crank.


But would having oil, valve lash set, and the intake and exhaust bolted on increase those numbers? Or is the motor most likely too old and crappy? Would an engine restore additive help those numbers as well? Someone recommended that on another site.

Help a newb out.

AlkyIROC

I'd recommend oil in the block. Hydraulic lifters need oil. You'll never get a proper compression test by cranking it by hand. If you can't crank it over with a starter, you can't do a compression test. I've had an engine sitting on the floor of the garage. Sat on the oil pan with 2 jack stands under the engine mounts. No exhaust manifolds. Ran a fuel line into a gas can, hooked a battery up to the starter and cranked it over to start it.

shanep1991

yeah you have to use a starter, that compression test might come out completely different and that engine might be perfect, i would set the valves too and put oil in it, no need to put a distributer in, just prime it while you turn it over

so, AlkyIROC, you started the engine with no exhaust manifolds? lol do you mean no exhaust?

BigWhiteGTP

I was hoping it would be somewhat conclusive. I mean, only one cylinder was at 30-40, all the rest were at 60-70. Still doesn't mean anything, eh? I know you guys know what your talking about.

built91Z28

Since the oil pump is run off the distributor, you would need a distributor.

AlkyIROC

No manifolds. Had nice flames shooting out the exhaust ports. I just needed to fire it up to show a buyer that it ran.