Inliners International Forums General Discussion Engines 250 bore

I am rebuilding my chevy 250 this summer would like any information I can get on it. Especially on boring .125 over throw in some 327 pistons. Also anything on cams and head work. I am trying to get as much power as I can, and still keep it streetable. As of now I have an intake and headers from clifford and an Edelbrock 500 cfm carb on it.

Brad, unless you want to be buying a new block, better stay with a .060 overbore and 307 pistons. The 250 is a "thin wall" casting and .125 over is living dangerously . Unless you have major $$ to spend, just clean up the head with a good 4 angle vavle job and 1.94 intakes. Cam selection depends on gearing, stick vs. auto tranny etc. Clifford or Stovebolt Engine Co can best advise you on this.

Brad,Three years ago and many passes
down the 1/4 mile along with many street miles,I built my 266 cid.
[250 bored to 4"] and have had no problems
at all. This overbore has been done many times. I did consult Tom Langdon of Stovebolt. and took his advise to have the block sonic checked for any core shift. Of the two blocks I have done myself, both had over the min. .100 wall thickness after the
boreing as advised by Stovebolt...

What ever you do, goodluck and enjoy the Inline Six..

Thick blocks in a 250. I was just talking to a guy atoday about that.. He said that some of the earlier 250s--mid 60s??-- had thicker walls.. You can tell them by removing the water pump and if the inner wall of #1 cylinder has been machined flat to clear the pump impeller, the length of the pump, then it is a thick walled one..

Just what I was told. Sounds reasonable...

PA

PA, Thanks for the input, I just checked one of my blocks that has .250 thick walls and the #1 cyl has been machined as you described. But, this block is an early 70's vintage.

Perhaps its the integrated head blocks that are thin walled??

Brad: We went thru three blocks in about 10 circle track races this summer with that exact set up. All blocks were sonic bored and we were running "hard" blocks for cylinder stability. All blocks split the cylinder walls. Granted this was racing, however, I would stay away from a 4 inch bore.

The best thing to do If you realy want or need a 4in bore on the block and Your spending that kinda money Best thing to do is spend a little more and sleeve The block then fill it. my 2cents worth. hope is helps }[oooooo]