The Stovebolt Site Forums The Shop Area Engine Shop Piston size..

Not sure but does anybody make pistons bigger than .080" over for a 235 chevy engine?

Jerry (HotRod Lincoln) may know or have some ideas. Personally I would stop at .080" over, but I've heard some people claim they had custom pistons made up to .100" over and had it work. My advice before you start boring over .080" would be to re-sleeve it and go back to stock size. We'll see what others think...

Pistons used to be available in what's called "semi-finished" size. They were then diameter-turned and cam ground to whatever size the engine builder needed. However- - - - -even if it were possible to find semi-finished pistons these days, those paper thin cylinder walls would cause an instant overheat situation, and piston ring life would be extremely short. Either sleeve all the cylinders back to standard bore and start over, or find another block. Is there some overpowering reason (like maybe an engine number that matches the title) to keep whittling on a worn out block? Unless you happen to have your own machine shop (I do) six sleeves and the labor charge to install them at today's prices will cost close to a thousand dollars.

Once you get custom pistons made in a too-big oversize, where would you start looking for suitable size rings to fit them?

Jerry

What is OD of the sleeve and its flange?

Press fit sleeves are not flanged. They are either 3/32" wall or 1/8" wall. Ask a machinist about the procedure if you're not experienced at doing it yourself.

Well with my cylinders approaching .090" the block will still stay in the shop and not considered a boat anchor yet? I had thought the cylinder walls were on the thicker side. So around here I can pick up a 235" for around $400.00 to $600.00 bucks. I could remember back in the 70's we'd had a 283" bored to .125" over. For back then with a set of 4:56's. Super T-10 some head work and a 3310 Holley with Headers, in a super light 55 chevy. Screaming fast, remember the 70's.

283 engines bored .125"oversize become a "301" (actually 301.46 cubic inches)- - - - - -Chevy cheated half a cubic inch when they put a 3" stroke crankshaft in a 327 block and called it a "302". Bored-out 283's usually hand-grenaded long before the cylinders wore out, but they were chronic about overheating unless a 4-core radiator was also installed. They did manage to turn 8K RPM with the right cam, carburetor, and exhaust system- - - -but usually for a very short time! I built a bunch of them for 1/4 mile dirt tracks.
Jerry

Yes, I can remember the 70s. They're gone, sadly...along with the youth I enjoyed back then. I can also remember the 50s, 60s, etc. If your cylinders are approaching .090" over, I'd say that block could only be re-sleeved if you for some sentimental reason want to save it or as you said used as a boat anchor. Think $$$ as Jerry said.

If you can find a late model (1959 and newer) 235 in decent condition for $400 to $600...decent condition meaning never re-bored or only bored out no more than .030" over, I'd get it, check for excessive bore taper, if none bore/hone it to .040" matching all work to new pistons that you give the machinist and make certain the machinist follows OEM specs to the dot (including ring gap), tidy up the crank and get all new bearings, do the head/valves, maybe get a new oil pump and be done. If it has hydraulic lifters, just remove them, carefully note which hole each came from, clean them up well, replace them in the same bores and re-use the camshaft with a new timing gear.

That's what I'd do anyhow. Good luck!

I would drop my 235 off at Jerry's place but dam he lives half way across the Universe from me. I sure wished the 60's and 70's were still here today, those were THE GOOD OL DAYS. Yeah today I have to lock up my trucks and the house.. Hey thanks Bolters for all your help..

Ol'55 ... I find it hard to believe that in the Palmdale area you can't find find someone with some aerospace machinist skills (and the concomitant passion) who can help you with this ...

Ask around ... I bet you can find someone who can help yu noodle this out.

Beat Army,
John

No, there are machine shops around here that will perform sleeving the block.They all start around $1200.00 and up.Could you sleeve that block on a Bridgeport mill? Like I had said earlier I can still find a 235 for around $600.00 bucks. I was just shooting in the dark earlier when I'd asked about .100" pistons. I just figured if anybody would know it would be that dude back in Tennessee, just kidding, like I said thanks for all the help.

The big problem with using a Bridgeport would be the limited vertical travel of the quill, and a lot of setup time. Both of my cylinder boring machines have a vertical travel of around 8-9 inches, so cylinders can be bored top to bottom in one pass. They bolt to the top of the block, and center up in an unworn area of the cylinder at least 2-3 inches below the cylinder head surface. Both of mine are Van Norman brand, and one was made during WW II. New, very good quality clones of Van Norman equipment are being manufactured in India these days at pretty reasonable prices.
Jerry

I have replaced press-in sleeves with flanges on a 50s era I-H 60 HP tractor. So they do exist. Probably not for a 283 Chev though. To install them one goes to the catering supply house for a box of dry ice and freezes the sleeves and taps them in with a block of wood and a mallet. Be quick about it or you will have to start overm maybe wasting the sleeve.

When I worked in the antique motorcycle shop we bored and sleeved all sorts of cylinders, Vincents, Sunbeams, Matchless V-twins, a Brough Superior, even a 650 Norton Manxman for which cylinders were NLA. Got to know the catering supply folks up the street quite well. Those days are gone these 30 years though. Sigh.

The tire curing presses I worked on for several years had huge bronze bushings (like 2 inches thick and over a foot in diameter, and 6 inches wide) supporting the big bull gears on each side of the machine that closed the clamshell mold blocks every few minutes to vulcanize the tires we made. These bushings had to be changed due to wear on occasion, and the way we shrank them to fit into the press frame was to soak the new bushings in a vat of dry ice and alcohol. A local company that refilled CO2 fire extinguishers provided us with dry ice when we needed it.
Jerry

I recall some years ago using dry ice and alcohol in our cool cans to keep the fuel extremely cold for Drag racing. The Good Ol Days..

Many older blocks have been "successfully" bored +.125", in that the engine did not seize immediately.
However, when up to operating temperature (oil, water, and metal) the cylinders are no longer round, or the same diameter at all points of the stroke length.
Bill Jenkins explained all this for the SBC 350 block in 1973. Boring beyond +.030" added 5 inches but ruined the ring seal.

Chevy didn't get stingy with their cast iron cylinder wall thickness until the mid-1970s. All the early stovebolt sixes and most 1950s and 60s small V8s will handle 60 over without problems. The early sixes handle 80 over as a matter of routine. Thinwall blocks came around in the 70s for both V8 and 6 cylinder engines. Ditto for cylinder heads- - - -don't get radical with a die grinder on the newer ones!
Jerry

Well if the Grump and Smokey couldn't figure out the early Chevrolet's, I don't know who could have?

The blocks we were buying from Chevy dealer parts departments 3 or 4 at a time to build round track engines came with a roughed-out bore size .005" UNDER standard bore diameter. They were intended to be bored and/or diamond honed to whatever bore size and piston skirt clearance the engine builder chose. Most of the racing teams I hung out with were building 3-4 engines a season, and if one had a thousand miles on it, it was considered to be an antique- - - -destined to be sold to a second-tier team. "There's no substitute for cubic dollars" in the round track game.
Jerry

Cubic dollars, haven't heard that one in about a minute. Hopefully we're not getting off the beaten path? If we are they can blame me. You might be familiar with the Bakersfield 1/3 mile dirt track, quite crazy at times..

We mostly ran the "1/4 mile" tracks at Merced, Watsonville, and Antioch. The actual length of those tracks depended on how they were measured- - - -inside, outside, or middle. Bakersfield was just too long a haul from Merced for the bunch I was working with at the time. When I got back home to Nashville and had access to a full machine shop and a couple of dynos we kicked things up a notch or two. Yep, the PC Patrol will be around shortly to give us 40 lashes with a wet noodle!
Jerry

Are you talking about this track?

Bakersfield Speedway

This thread has run it’s course.