I have a 1971 250ci L6 in my 1965 C10 truck. Mileage is unknown. It was free to me from a parts truck I bought. I ran the engine in the yard with a newly rebuilt carb 2 years ago. Compression seemed pretty good before I pulled the engine.
Fast forward 2 years. I've got my truck on the road finally. Engine runs great and starts right up. Rochester B card with HEI and stock manifolds and brand new single exhaust pipe from the manifolds back. Absolutely no oil leaks anywhere. All seals and gaskets are NEW except I never pulled the head or freeze plugs.
It goes through 2 to 3 quarts of oil per 11 gallons of gas. Gets 15-18 MPG. Starts right up. Smokes visibly when I goose it. Tail pipe has dark black soot.
I guess it needs rings. PVC is properly hooked up. I popped the PVC out of the rocker cover and there is great suction on the end and the engine stumbles when I put my hand on the end.
My plan is to re-check compression. Then wash internally with kerosene. Add kerosene to oil, then idle at 1500 RPMs in the yard for 15 minutes and drain everything while it's hot. Theory is that it might help remove carbon and allow the rings to seat better (does that sound right?).
So, if this was your engine, what would you do?
If the advice is to rebuild, would you rebuild an 88K mile 1965 230ci block as a 250ci or use the 1971 block? The 1965 230ci had bad compression in 3 cylinders for reasons unknown and that is why I used the 1971 engine. I still have the 1965 230ci under a tarp. 
Last edited by Lugnutz; 09/15/15 01:56 PM.
