The Stovebolt Site Forums The Shop Area Engine Shop what kind of power

looking for anyone who might be able to give me an approximate gas milage/power range with the following modifications to a '55 235 ci: bored 80 over, new rings and pistons, new rods, hardened valve seats, patricks mild cam, fenton cast iron dual headers, clifford intake w/ holley 500 cfm carb, 3.08 rear end...am hoping to get my 53 1/2 chvy ton on the road this xmas, any comments appreciated
mahalo

heh-heh Boy are you a newbie!

I don't know if I'd want any engine bored .080 over. Too much potential for disaster. An .080 overbore usually means at least two previous rebuilds. Those cylinder walls should be examined closely if you choose to proceed.

Sounds like you have a reasonable dream - decent power and fuel efficiency. I hope you realize the cost of bringing that dream alive - $$$$$.

One last thing - it's difficult to give you an mpg figure without knowing what kind of '55 vehicle the engine is going in (car/truck?) and what your final drive ratio will be. And then it will be a guesstimate.

He may be ok though, I seen where a 235 ci can take up to .125 inch over bore. There is alot more meat in these blocks than the thin wall castings of Chevy's v-8.

You can take a 235 block .080". Just make sure the cooling system is in top condition, and the machinist checks for bore stagger. Because if the cylinders have been previously bored a little off from stock bore centerline, going .080" will be close to a water jacket.

A 235 block requires a sonic check of the cylinder walls if going to .125" to make sure you won't hit water.

If you're going to use a M4F cam and keep the RPMs below 4,000, you could get better throttle response with a smaller carb. The Holley 390 I had on my 235 worked really well. Make sure you have the bottom end balanced, as the 235 only has 4 main bearings. Balancing helps the bearings live longer.

As for power, let me flesh out your setup. It sounds much like the one I'm doing now, except I'm at .060".

All the stuff you mentioned, plus:
"mini" HEI distributor
898 high-compression head shaved .030" with mild porting/blending
engine balanced
aluminum timing set
M4F cam degreed in
clifford dual-coil valvesprings
New rocker assembly

You might average anywhere from 12 to 17 MPG with that setup and easy driving.

The street HP potential of a 235 has been argued much here over the last few months. We agreed that a well prepped "hot" 235 is good for 175-200 HP at about 4750 RPM and 225-250 lb-ft of torque at about 2500 RPM. But most guys here would advise against revving a 235 past 3500 RPM if you want it to live.

hope this helps

chip

Just bolt you in a 250 and run it at 3000-3500 rpms all day, once you get it built. 7-bolt mains and a shorter stroke allow the engine to take higher rpms than the 235. Plus it's compatible to the newer Chevy trannies.

But good luck on making the engine mounts work.

-ftyler

mahalo guys for the estimate and advice...you're right ftyler, i am a newbie to this expesive hobby
but gotta learn sometime... i read this site religiously for alot of good sound advice from all
you experienced stovebolters