The Stovebolt Site Forums The Shop Area Engine Shop Re-bore limit for 235 ?

Am going to be helping a friend go through his accumulation of 235 engines that have been laying around since before I was born...

How much can the average '54 - '62 235 be bored-out before running-out of meat and/or have to be sleeved ?


Thanks...

Frank,

I have always thought the "practical" limit was .060 over. More than this might be getting into the hot-rod arena.

Availability of oversize pistons and rings will be a limiting factor also.

Stuart

Arias, Ross and others can make pistons whatever they need be. Stock piston sets are generally available up to .060. Most of us would not be comfortable boring a 235 to the maximum that it can be bored, i.e .090-.120. Some race engines have been bored to .125 over standard. So I agree that the practical limit should be limited to stock parts.

According to Frank McGurk, 3-21/32" is no problem whatsoever for any 235. He goes on to say that if your cylinder block casting is anywhere near uniform in thickness you can go to 3-11/16".

However, if you bore to the maximum the engine cannot be rebored 50 years from now. If you need more power I say get a 261 and bore the minimum that is truly necessary.

I built a .060 over 235 motor for my '55 B/A car & ran it for 130K. mi. before replacing it w/ a 292. It did great, running daily in summer temps of 115+ on the I-state at 60+, up 4000 ft.+ climbs, just a great little motor. Wanted a bit more power is only reason I repl. it. Had no noises or oil consumption when I pulled it. Used normal rebuilder quality parts in it, no hi dollar stuff. Sold it to another member of this site. Doug

Thanks guys...

At least we'll have some perspective if we start finding blocks that've already been punched and stuffed with oversize pistons...

My friend has been scrapping vehicles and other junk for over forty years, and stockpiled a bunch of engines ... now it's time to "clean-up", see what's still viable and what's just junk...

I appreciate the responses!

I am in the midst of building a '60 235 and just had it bored 0.080" over. I bought new pistons from Patrick's and was told that 0.080" over is about the limit for a 235. I'll let you know in 50 years how its held up.

As for your stock pile, if you come across any decent oil pans or starters, let me know.

RedGreen.

Frank-I have heard that .60 over is about all you want to go. I rebored my 235 to .40 over and had no problems getting the oversized pistons and rings. The 62 1/2 ton has been about 30K since rebuild with no problems. You get a little more power with the rebore but not a whole lot. I still have room for another rebuild if I live long enough to wear this engine out-which is doubtful..

.080" pistons and rings are available. I have bored several to that with no problems.

That would make it a 246 cubic inch engine, wouldn't it?

Yes, 0.080" over would make a 235ci into a 246 ci. With a 3/4 race cam and a T-5 transmission, (and possibly dual-two barrel carbs) it should make for a fun engine.

Howdy,

I wanted to reopen this post as my '60 235 is currently over .080" and needs to go to .100" with the bore and pistons. Can anyone who's actually done this tell me how their engine's held up? I'm thinking a good cooling and exhaust system would be essential.

I built up a 235 and bored it .080 over and the crank was turned .040 under over 15 years ago in a 1952 3100. I sold the truck to my neighbor across the street probably 5 years ago and it is still going strong. And I might add it is very responsive.
Cleon

I forgot to mention, my machinist also wants to raise the compression ratio by milling the head .100. I think stock is around 6:1, and this will bring it to around 8-9:1. A 35-50% increase in pressure in the cylinder and .100 off the walls sounds a little nuts.

Stock compression on a '60 motor with an 848 head is already about 8 to 1. Going over bore that much is going to raise it probably another 1/2 point. I would only take enough off the head to flaten it and no more.

If it were me, I'd probably be looking for another block anyway that could be bored .060 or less unless it's a number matching thing. These engines are very easy to find for not much $$. Keep and eye on craigslist around your area and they'll pop up.

-Ed

I went ahead and traded it for a rebuilt 261 block from another shop (and actually saved over a 1000 bucks!). .100 over and a raised compression would be ok for a dragster, but I'm planning on this thing running at least 75000 miles.

Thanks for the input.