The Stovebolt Site Forums The Shop Area The HiPo Shop How far can a 235 cylinder be bored?

Has anyone ever tried boring a 235 cylinder until you hit the water jacket? While I was researching the possibility of installing slip-in sleeves into a 261, I got to wondering if the same concept could be applied to a 235. I've done similar things to truck pull engines with a MOPAR hemi block, but those engines had the water jacket filled with epoxy before we started whittling on the block. By the time the holes were big enough to slide the flanged sleeves into place, we had stripes of epoxy showing in places where we had bored all the way through the original cylinder walls. Those engines only ran coolant in the aluminum cylinder heads and ran for a minute or two, tops, during a pull. We were getting 547 cubic inches from a "426" hemi with the bore and stroke combination the truck owner preferred, and engine life was measured in minutes, not miles! The 40% overdrive blower and alcohol/nitromethane fuel mix might have had something to do with that, though!
Jerry

Jerry, I don't think that would work well on a block filled with coolant. The coolant would get between the block and the sleeve, and possibly escape at the bottom of the sleeve if it wasn't press fit there. Even if you could seal the bottom of the sleeve, it may be next to impossible to remove the sleeve (assuming you wanted to) once the engine had been run and coolant baked between the sleeve and the remnants of the cylinder walls. Also, the block strength might be compromised without original metal between the deck and the bottom of the cylinders.

I'm thinking that a flanged sleeve retained by the cylinder head might be able to be used if the bore size did not actually penetrate the original cylinder wall diameter. Not necessarily the 96MM ID sleeve I'm planning to use in the 261, but a similar concept with a somewhat smaller bore size that would allow the 235 block to use replaceable sleeves. I just used the 426 hemi example as what can be done when long engine life is not an issue. We estimated that hemi was producing in excess of 1600 HP when it broke the crankshaft into three pieces, but the cylinder walls stayed intact. A 235 might be able to use a 3 5/8" bore diameter flanged sleeve, or maybe one slightly larger and still retain enough cylinder wall integrity to be reliable for street use. Another example of a huge overbore and a wet sleeve was the 2300 CC Ford 4 cylinder dirt track engines we built with 283 Chevy pistons and 3 7/8" diameter, 1/8" wall sleeves. Those sleeves ran wet on the back side with the bottom of the water jacket filled for about an inch with a product similar to JB Weld, but a LOT tougher. Those engines ran an average of half a season on 1/4 mile dirt tracks before hand-grenading, running in excess of 9K RPM at the end of the straights.
Jerry

Edit: It looks like this one could be fitted to a 235- - - - 92MM (3 5/8") bore, with replaceable sleeves. With a 4 5/16" stroke, that engine would have 268 cubic inches. Ford 223 inline sixes have 3 5/8" pistons (Silv-O-Lite # 1079) that would work well with that stroke and modified 235 connecting rods.

www.ebay.com/itm/354717791476?

Jerry

I don't know, Jerry. You're starting with 3.56" in the 235 and that sleeve is what...3.74" o.d...95mm? That is .18" over or .09" on each side. It might work. I'd be a lot more comfortable if we were taking out .06" though.

Around 1976 a friend who owned a machine shop here had to sleeve a 235 and I want to say the sleeves came in a couple of thicknesses...maybe 1/8" being the thickest. You'll know about that, I'm sure. Anyway as I recall he was sleeving to repair one cylinder only and the piston was already 20 or 30 over so he used the larger sleeve. If I'm remembering right about the 1/8" part, I think it would probably work. 1/8" being about 3mm.

I prefer 3/32' wall sleeves unless there's a hole in the cylinder wall. Then I use the 1/8 wall sleeve for more support for the piston with nothing behind the sleeve. It's necessary to bore the hole about 1/4" oversize, less a few thousandths for a press fit, to install a 1/8" wall sleeve- - - -at least for the 200 or so I've done in the past 50-something years. I used to buy my competitors' "worn out" racing engine blocks for pennies on the dollar, install 8 sleeves as a training project for my students, and outrun those guys the following season with their own junk. Some of them never figured out what I was doing.
Jerry

Jerry, this is solely from memory nut I believe on the inliners website, a guy buy the name of Curt B had pictures of a 235 block taken to a band saw to show wall thicknesses and water jackets. Hope you find it and hope it helps.

If we amend the subject line to: How far can a 235 cylinder successfully be bored?

Years ago when I rebuilt my '55 235, was told by the machinist that 0.060" over is the safe limit. Still the case?

No, and it never has been the case. Your machinist had his head firmly inserted into a very dark and stinky place. I've seen untold numbers of stovebolts running many thousands of miles with an 80 overbore, and some race engines with 125 over (1/8") pistons for a fairly short time, producing far more horsepower than a street engine. To install a 1/8" wall sleeve, it's necessary to bore the block 1/4" oversize, hopefully without hitting water. I'm pretty sure boring and honing the block big enough for a snug slip fit for a flanged sleeve that doesn't need a press fit to stay in place won't be much of an issue.

I got started down this rabbit hole while researching parts for the 261 engine I'm working on, the one I'm hoping to build with a 24 valve, dual overhead cam, cross flow cylinder head. That one will have a steel adapter plate bolted to the top of the block, one which also retains a set of flanged sleeves that project slightly above the surface of the block. That's a pretty imaginative pipe dream right now, but it's beginning to look doable, with some creative machining and a little bit of luck.
Jerry

Good to know can safely go 80 overbore if engine is opened up again. Engine has 100K miles since rebuild, still with normal oil consumption.

Giving benefit of doubt to the machinist some 40+ years ago, he was likely erring on the safe side. I would hesitate to cast aspersions!

Back when there were lots of blocks available to whittle on, 30 or 60 over was the preferred choice. The engines with an 80 overbore were sold mail order by places like J.C. Whitney, Sears or Montgomery Ward, with a fairly short warranty (or none at all) to people who wanted to keep an old beater car or truck running a while longer. As usual, the skill of the rebuilder and his attention to detail had more to do with the quality of the job than specific over or undersizes. 30 under crankshafts were also relegated to short life, low cost rebuilds as well, with standard, 10 or 20 undersizes preferred. The stroker shafts I have in mind for the engines I'm working on will have rod and main bearing undersizes approaching 1/8" below "standard" shaft sizes, so as long as bearing clearances are correct on the resized shafts, original diameters can be ignored to some extent. Stovebolts were WAY over-engineered in a lot of places, compared to more modern engines.

Your high mileage 60 over block might be a very good candidate for conversion to slip fit flanged sleeves, if you can find a machinist willing to think outside the box. That's exactly the situation I have in mind, to save blocks that might be scrapped otherwise.
Jerry

Since this is the HiPo shop, I'm aware of different perspectives for developing high-performance and shorter-life engines. My truck engine was built in 1978 for long life and regular use.

The rebuilder was me. 60 overbore, 10 under crank. Original cylinder head and valves were set up before Unleaded was the only fuel available. It's the truck's original '55 high pressure engine with insert rod and crank bearings shimmed for correct clearances.

If 80 over pistons would be required, who makes them? I recall back in the day, 60 over piston was the max kit size available in the retail market.

You can usually find 80 over stovebolt pistons on Ebay, and the online sellers like Rock Auto, and other similar outfits either have them, or they can be drop shipped from the manufacturer after they lie to you about what they have in stock. The Silv-O-Lite part number for a 235 piston is 1413. Type Silv-O-Lite 1413-80 into your browser, and I believe you'll find multiple references to different companies who claim to have them in stock.

Here's what a 30 second search a couple of minutes ago found- - - -one of several hits:

www.ebay.com/itm/254832990346

Piston rings, gaskets, valves, bearings, and similar rebuilding parts can be found the same way. I haven't bought a "kit" for any engine I've built in many years. Find the applicable part number and do a search, or do business with a professional parts supplier.

Jerry

ol 55, Here's a full set of .080 over rings for your 235 to go with Jerry's find if you are going this route? Might need to go after 'em quick as seller indicates it's their last set available and I didn't see any others from other sellers at the moment.

Does anybody else remember the Chevy Vega 4 cylinder engine- - - -the one that had aluminum pistons plated with cast iron running against an acid-etched high-silicon aluminum cylinder wall? There was no way to replace a piston in a scored cylinder, so GM said a damaged block had to be scrapped. I made a good chunk of pocket change back then, boring and honing those blocks for flanged sleeves, and fitting conventional aluminum pistons to them. After a couple of disastrous years of production, GM started putting cast iron sleeves and aluminum pistons into factory blocks.
Jerry

My parents bought a new Vega in 1972. It turned them off American cars for a nearly 3 decades. They dumped that Vega after less than a year of ownership and purchased a new VW Super Beetle. The Beetle was subsequently traded for a Toyota pickup in 1980.

After 23 years of ownership of the Toyota, my dad sold it and bought a 1976 F-150.

In a perfect world with a brand new 235 block, probably .100 maybe even .125. But after all these years of use and corrosion on the outside of the cylinders in the water jacket, you would really need to sonic test the block. I had a 261 block bored to .030 and hit rust. Other 261blocks went .060 no problem. All depends on the actual wall thickness.

In the decidedly imperfect world of real life, while making a living doing, and teaching automotive machine work, for 50+ years, I routinely bored all kinds of engines either 187 thousandths or 250 thousandths to install sleeves. Sometimes I hit water, most of the time I didn't. Either way, we installed the sleeve and assembled the engine. Very few, if any, gave any problems. I watched my father bore several flathead Ford engines 250 thousandths oversize without sleeving them, and run 11.5:1 compression on alcohol and peroxide, at over 6K RPM . He would offset the center cylinders a few thousandths away from a thin area where the exhaust passage went between them, and narrow the top of the connecting rods to let the pistons center up in their bores.

There's a lot that can be done to make engines do what we want them to do, once we get over being timid about whittling on heads, blocks, and crankshafts.
Jerry

You are thinking of an 848 head that I digitized, cut up, analyzed, modified, and flow tested. When curiosity gets the best of me I turn to the machine tools for answers rather than forums. It's disappointing to me that HRL does not demonstrate and show us what is possible rather than just asking and debating possibilities.

Is there a shortage of 235 blocks? I'm sure I have some in the scrap pile. Should I dig them out?

Pressure lubed 235's had a production run of a little over 10 years, 1953-63. While they're not particularly scarce yet, the newest ones, including "service replacement" blocks, are approaching 60 years old. Try finding a 1st. series 194 or 207 Chevy six from the late 1920's or early 30's these days.
Jerry

Curt, I remember when you originally did this. I think I remember first seeing your photos over at inliners, at least that is my memory but that could be wrong. What I don't remember, and I apologize for my lack of attention, was what your ultimate conclusions were as to what if anything was helpful with these heads.