Hot Rods Small block Chevy 307 pathetic compression

What would cause a basically stock 307 Chevy that had new rings and reworked heads done on a 30.000 mile engine (came out of an old farm truck that was low miles but rusted to pieces) back in 2008. Probably about 30-35K on the engine since then. Had a carburetor fire. Replaced carb with a 550 Edelbrock. Getting fuel and fire and timing is right but won't start. Compression test shows 2 cylinders with decent compression--110 on #3 and 115 on #4. Rest of them are around 60 except #7 which is only pulling about 40. Why would a relatively low mileage engine have such abysmal compression? Probably looking for another engine but curious to know what killed it.

 

The motor has been sitting since 2008?

Probably rusty cylinder walls. Stuck rings. Valves not seating. The only way to find out is pull the heads.

 

Replace the cam and lifters... The lobes on the cam are probably wiped out....

 

So it’s got 60-65K miles. Rusted, rings, carb fire, but never a rebuild. I’m betting those heads didn’t get every thing they needed with 30k on them. Used about 2500 miles a year, that’s a lot of sitting I’d think it’s ready for everything but id squirt some oil in each cylinder and do another comp test for ring condition. If your up to it and have a leak down tester you can do each cylinder and listen at the carb (with the throttle plate open) and the exhaust pipe for air leaking and then you will know. You can hear leaking air at the oil fill for the rings too.

 

Was running up into 2019, I had some recent health issues and just getting back in shape to work on it.

 

Tell y a (hopefully) quick story. New car with Chevy V8. Ran near daily. The was only started every few months for about 10 years. Got it going (after OT changes) ran pretty good till the head gasket gave up.
Now all the while @runming pretty good) was not running great. Had a miss/ stumble when idling.
When the head gasket went to hell and I pulled the heads, a head bolt at #7 pulled right out.

I pulled the engine after looking at the bolt, it was showing sign of being broke for a long time, my feeling was when I bought it new. # 7 ring pack was stuck with lots of rust on the rings.

So if the old squirt oil into the cylinder and recheck compression brings it up, it’s a ring/piston issue, if not, poor valve sealing.