i just picked up a 1957 chevy pickup. it has the 235 straight six. i was able to turn the crank by hand. after talking to some guys from other forums they suggested to only bore the cylinders .010. just to clean them up and replace the pistons and rings. they said it didnt matter in performance if i went bigger on the bore. also they told me it wouldnt be worth getting a bigger crank too. but they did mention i could change out the cam rods and lifters. i am new to the straight sixes but i know i can have this motor beefed up and running like a 265. any suggestions about how to go about this? thank you.
There are upgrades you can do.Just don't expect big jumps in performance. Firstly,make sure you have the block checked for cracks.After all these years it is not uncommon. The attached sight has some info on parts that are available.
http://www.patricksantiquecars.com/
thanks drew for pointing out the possibility of having a cracked block.
I wouldn't be too concerned with a cracked block. Heads on the other hand is a different story. Get them checked. If you are going to bore an engine, I say go big or go home. A well worn engine could already be at .010 over. Go with at least a .030 over. Back in the day it wasn't uncommon for hot rodders to go .100 on overbore on the stovebolts. Keith Black still offers .080 pistons. Patricks, Egge, Langdons, Clifford, and Larrowe's are all good places to start looking for performance parts. Most Trucks will have a solid lifter cam, being yours is a 57 it may have been drilled for hydraulics too. Check your casting numbers on the block and head to see what they are. Patrick's also has a good csting number guide. Anyhow, good luck.
one of the biggest gains to be made to 235s and 261s is by boring... and a bunch, .125" if the block is sound. In McGurk's dyno tests done on a 261 in the Jan. 1955 HRM article, An eight inch overbore really woke up the torque figures. There are procedures to stroke the crank upwards to 3/16 longer by offset grinding the rod journals to a 292 journal size and using those rods-special pistons will be needed and can be furnished by Ross?, or was it Egge? An eight over 235 is 252inch, and I have ridden in these-they have a definate whomp on your back when you hit them with 3.55 or lower gears, and with an additional 3/16 stroker its at, what do you know, 265! (definately the hard way-but you wind up with better rods) An eight over and 3/16 stroked 261 is a 292!! I think one of the card bearing Inliners has one in an early Chevy Twice racer. I would almost say to bore one .10" a real waste of time and money. All my experiances with hyd 235/261 were not good. those hyd lifters are huge and heavy, along with the solid rod type pushrods they make for a really heavy valve train--use solids and tube pushrods. find a reprinted McGurk hop up manual at panic's place? or amazon-Its the Bible for these motors. Maybe if ol' Frank used one of his stovebolt motors at the '38 or '39 Indy, instead of the Offy, He might have qualified!
A place to look for cracks, (have not seen mentioned on these pages) especially the 261s, is the main bearing webs, as it was common place for these ol' warriors to be "lugged" around intersections due to their low speed torque, (this was a "tip" offered in Hasting piston ring packages) back in the day as they say. See, it dont hurt to be old, Imagine spending a fortune on boring and pistons only to find a crack in one of you main webs- these motor only have four mains (but they are big).