Question What would the compression be on a 1989 tbi 350?
What would be the stock compression on a 89 tbi 350 be? It is a 4 bolt main truck motor. I have heard it to be around 8:3:1 which was not what i wanted to hear at all! Any information would be great. Thanks, rob.

Best Answer Your measured compression ration (actual) will almost certainly be at least 1/2 point below the advertised (specs) compression ratio. This is due to manufacturing tolerances. Less compression will be less harmful than too much so tolerances are set such that the compression typically comes out low. After WWII the US rebuilt Japan and installed newer, more accurate machinery for them. They were therefore able to build more accurate automobiles than the US. Now the US has mostly replaced old and aging machinery with newer stuff the tolerances are lower and the compression comes out closer to the design than before. 1989 is near the end of the older machinery and near the use of the newer machinery. So somewhere between 8.1 and 8.7 compression. In my opinion that is not enough of a range at that low a compression to have much of an impact. Don't worry about it.

Question Where can i find a new 350 engine block?
Im looking to buy a 350 engine block so that i can start building a new engine to put into my 1993 gmc sierra. I want to build something of higher than stock compression (8.5:1 is stock) and maybe supercharge it so no matter what block it is, i would want it to be re-sleeved with something stronger than stock cylinder walls but thats something i can focus on getting once i get the block. Where can i find some good quality 350 engine blocks?

Best Answer You don't "re sleeve" a chevy engine. The cast iron cyl walls are more than strong enough for 800 + HP The idea is just not to bore them out too much and make them too thin. .060" over is max over bore. At .040" have block sonic tested to see if it has enouh wall thickness to go .060" You don't use high compression, and supercharger. In fact you want lower compression with a blower or turbo. The boosted engines I build, I run 7.5 to 8.5:1 compression then run 7-20 psi boost depeding on type of forced induction and setup. You eaither build a high compression NA engine, or you build a lower compression forced induction engine. My engine in my camaro is NA, 10.34:1 compression, 600 HP. The engine in my dad's firebird is a 8.3:1 compression twin turbo'ed engine running 12 psi boost, making 700 hp Both are built from core blocks. Mine is a 1971 350 block, his is a 1969 327 block. Both came from a junkyard. $150 each for the core engine with intake down. Everything was took off and scrapped. The only parts we reused was the blocks. Had them hot tank cleaned, bored and honed, line bored, decked. Then went with aftermarket crank, rods, pistons, heads, etc You don't 'need' a new block. 90% of all performance engines, hot rods, etc that people build, starts from a good junkyard core block that they have machined. The only new chevy 350 blocks that are being made is by GM performance parts for use in their crate engines. Check with GMPP, jim pace, SDparts, etc. Other new blocks are aftermarket race blocks for 1000 HP builds like the brodix, dart, world blocks Summit racing and competetion products sells ready to build 350 chevy blocks but they aint new. Its just a core 350 block thats been machined