I came across two 250ci Chevy engines to replace the very sick one in my 46 2-ton. One is a stocker out of a 1971 Nova. The other, a 1978 model (non-integrated head) was supposedly rebuilt with new valves, an RV cam and a 4-barrel intake. I did a compression test on both engines after getting them home. While the stocker tested great, the best hole in the "rebuilt" one only tested 30 PSI! I don't think that's enough compression to fire ether, let alone gas.
I pulled the entire engine down today. I can plainly see the fresh cross-hatch markings of the cylinder hone in the bores... and a lot of carbon on the piston crowns. Cylinder bores and piston skirts all measure what they are supposed to (although the piston ring gaps weren't alternated like they should be). I thought maybe someone mistakenly used some 230ci components, but the block, head and crank casting numbers all say it's a 250.
I'm not sure where else to look. I figure the excessive black carbon on the piston crowns is resultant of a 4-barrel carb mixed with the low compression. Oh, and the head gasket I removed doesn't look like it ever sealed. Thing looks brand new, other than the carbon sticking to it. Even the impregnated "glue" around the coolant holes is intact. No signs of a gasket breach anywhere.
Any ideas???
