350 chevy sanity check. (1 Viewer)

[trainbufftony]

I bought a 350 tuned port engine out of a corvette, 1987 model year. Bought a painless harness and I intend to put it in an El Camino for my sister.
I bought the engine used from my neighbor who is no longer with us. He had it stashed for at least ten years, maybe 20.
His Dad got it for a boat which never came together. His dad was pretty clever, and a competent wrench, but both of them are no longer with us, so I get to answer my own questions with this block.
I poped a valve cover and it's extremely clean inside.
I bought a starter, charged a battery,and decided to run a compression test as a first step, before I commit lots of money to this plan. First two holes hit 125 on the first crank and settled at 175psi of compression. 3 hit 150, 4 barely made 100 psi.

The other side made ~165 across all 4
I took a deep breath thinking to myself, that I may have gotten burned, and I may need to overhaul this motor, and it's going to quickly spiral into an expensive project.
Tony chill.
My inner mechanic wasn't convinced.
I recently loaded up a sure shot with marvel mystery oil, so I shot a bit in each of the low cylinders, then let it sit a while.
Comp came up from ~100 to 125, and the exhaust valve was clearly leaking, evidenced by marvel mystery vapor coming out.
Well dang.
I let it sit a bit longer and hit the switch again.
Within 2 cranks I had nearly 180psi.

Here's my theory.
The valves on those 2 cylinders were open, began to surface rust, and wouldn't initially seal perfectly.
A shot of lubrication dissolved the rust and brought the comp back.
I think the engine is fine.
Bill (the guy who pulled it) was no dummy
It's spotless clean inside.
Been stored for at least a decade, maybe 2+
What do you think?

Do I need to overhaul this thing, or do I stuff it in and send it?

I'm excited for the thing to be done, it will have nearly as much torque as the Cummins in the driveway.
But, it's going to my sister, so I want this to be 100% OK for her.

 

[Broski]

Stuff and send

I would bet the the rings were a little sticky after setting so long also Mystery oil loosened them up.
In hindsight you should have put it in before hand.

 

[FuglyYota]

I agree on the rings needing to reset. I also think you could have valves needing to reseat. I’m also assuming you put oil in the motor befor spinning it. Squirt more oil down the cylinders, let it sit. Then get a pre lube tool for your drill, a cheap oil gauge, and spin with the drill to make sure you get good oil pressure. Watch for oil to get up to the rockers. You may need to slowly turn the motor to get lifters aligned. If you get oil pressure and oil at the lifters, crank and watch compression again. More than likely you’re good, but best thing to have done would have been to pre lube the motor before cranking after that many years sitting. You want oil at the lifters and cam pretty quickly.

 

[trainbufftony]

I agree on the rings needing to reset. I also think you could have valves needing to reseat. I’m also assuming you put oil in the motor befor spinning it. Squirt more oil down the cylinders, let it sit. Then get a pre lube tool for your drill, a cheap oil gauge, and spin with the drill to make sure you get good oil pressure. Watch for oil to get up to the rockers. You may need to slowly turn the motor to get lifters aligned. If you get oil pressure and oil at the lifters, crank and watch compression again. More than likely you’re good, but best thing to have done would have been to pre lube the motor before cranking after that many years sitting. You want oil at the lifters and cam pretty quickly.

Good point on the prelude. That would have been smart, however I don't think I did any real damage by performing a comp test with the plugs out.
Honestly I like the idea but I need to get an oil filter on it first and the adapter for the filter is missing or incomplete so no oil filter at this time.
Using my flattened piece of fuel line to prime the engine would just make a mess on my floor.
Didn't want to spend anything until I knew I had a viable engine, and it's looking like I've got a viable engine...