The Stovebolt Site Forums The Shop Area Engine Shop 1954 chevy 235 main bearing cap question

I am rebuilding a 1954 Chevy 235 engine and I did get some help from Jerry and modified my block to except 1956- 1962 main bearings. That worked out well and looks good. Thanks Jerry.

But I have run into another problem as the third bearing (thruster bearing) cap does not have a hole for the dowel on the new bearing. The number on the cap is GM 39 701347 R and has a tapped hole on the top of the bearing cap.

Does anyone know if this bearing cap is an original 1954 235 engine bearing cap? The new bearing and the old bearing are the same size and it appears the new bearing would work if the cap is drilled for the dowel or if the dowel is removed from the bearing, which may be easier.

What are your thoughts on this?

This engine history is unknown to me but it appears to be rebuilt at least a couple of times as the cylinders have been bored .04 over and are perfect with no taper at all while the crankshaft journeys are at .01 under size, are in specification while the bearings are showing a few small areas worn to the copper alloy and needed to be replaced.

I have 1953 and 1950 216s and the tapped hole is for the oil pump pickup that bolts to that cap. The 1950 cap has no dowel hole (don't know about the 1953 as I haven't pulled that off.) You're likely going to have to drill a hole for the dowel on the bearing insert. I plan on installing a 235 crank in the 1953 engine and per Jerry the #3 cap and block have to be machined to narrow them for the later 235 bearings to fit. If you don't have to do that, you're lucky as a local machine shop has guesstimated that work to cost $1000.

I don't know about the oil pickup on a 1954 235, but if it's not needed, you can ignore the hole on top of the cap. It may just be a carryover from the 216's.

That hole isn't particularly critical- - - -with a little careful setup on a drill press you can make a dimple in it to receive the nib on the bearing. Puta dab of Prussian Blue on the nib, and carefully slip the bearing over the cap. Once you have the spot marked, simply drill a shallow hole so the bearing shell will fit snugly into the cap. I don't think it would be a good idea to file or grind the nib off the bearing. That would only leave the tiny tab on the upper shell as the anti-rotation safety device. Chances are the crush on the bearing shell would keep it from spinning, but the dowel would add a safety factor.

Kevin- - - -I'm building a self-aligning fixture that bolts into the bearing webs with a big side milling cutter to narrow that thrust bearing web on the 216. It can be driven with a variable speed 1/2" drill motor. Once I get the fixture finished, I could probably loan it out to stovebolters who want to whittle on a 216 block and don't live close enough to me to bring me their engines. I hope that your "machinist" uses a lot of K-Y Jelly if he charges his customers rates like that!
Jerry

It is Alaska, Jerry. It's know as the Alaska Gouge.
If you get that rig put together I'd be happy to pay postage both ways to use it. That would be way less than 1K. I haven't committed to that job yet.

I'll post a few pics of the jig I'm designing. The job could also be done by standing the block up on the base of a floor mount drill press for more precise control of the cut. Both sides of the web will need to be cut to preserve the alignment of the timing gears. It has a 1 1/4" shaft, and runs in ball bearings centered up in the #2 and #4 bearing saddles. I bought the side milling cutter on Ebay. The depth of cut will be controlled by a shaft collar clamped to the shaft. "Designed and built by R. Goldberg"!
Jerry

Kevin - is the 235 crank in the 216 block going to give you full pressure oiling? Pressurized rods? Is that the idea?

Yes, and it also increases the displacement of the "216" because of the longer stroke of the 235 crankshaft. Buick 215 aluminum V8 pistons are used to compensate for the longer stroke. A 60 overbore and the 235 crank makes the "216" a pressure-lubed 235, without changing the outward appearance of the 216 engine. A Melling M-29 oil pump (same as a 54/55 235) is a drop-in fit to provide the oil volume needed by the pressure lubed crankshaft and rods.
Jerry

What will the new cu. In. of this sleeper end up being?

EDIT: I did the calculation and came up with 235. Nice!

Just a quick note to answer your question. Per the 1929-54 Chevy Master Parts Book, it looks like your cap is the correct one for the '54 engine. Just in case it may ease your mind.

Have to modify that Buick piston and/or connecting rods to make the pistons work? I remember you talking about this, just can’t recall all the specifics.

Just a few minor tweaks to the pistons and rods are needed. There's also a piston for a Mitsubushi 4 cylinder Diesel forklift that can be used by putting bushings in the wrist pin bores to fit the 216/235 piston pins. That diesel piston has a crown thick enough to machine it level with the top of the block with a variety of altered crankshaft strokes. A "stock" engine is just a blank canvas that an "artist" of a machinist can use to paint a masterpiece! Phil, with different connecting rods and a stroker crankshaft, a 216 block can get slightly over 250 cubic inches- - - - -and still look original from the outside.

www.ebay.com/itm/163130694013?

Jerry

Jerry after you and I spoke on the phone a while back about making my 216 a full pressure 235 (with the crank from Amtrak Joe) I went to Heard Machine (here in Southern Maryland) he’s interested in doing the machine work and said he can call you to discuss the details. Hopefully by spring we have my original engine back in the 41 fire truck.

Sounds like a winner! I'm backlogged on work already, since for the past several months my main priority has been dealing with several medical issues my wife is having. I'll be happy to "share the wealth" with anyone, machinist or not, who is kind enough to listen to me! Lots of professional shops have to deal with less labor-intensive, more profitable work than whittling on an old stovebolt!
Jerry

Here's a few pictures of the block machining fixture I'm in the process of building to narrow the main bearing web on a 216 to accept 235 mains. That will avoid the necessity to modify the 235 crankshaft, and will also make it possible to use the later model 235 main bearings in the 216 block. The early (54/55) 235 mains are getting extremely scarce and expensive. The fixture will be turned by adapting a piece of hex shaft to the end of the mandrel, standing the block up on the base of a floor mount drill press, and turning the cutter at very slow speed. Depth of cut will be set by using a shaft collar to limit the downstroke of the mandrel. Any "machinist" who claims he can't do something like that needs to turn in his man card!
Jerry

Jerry, one more piece of the puzzle is cutting a chamfer on each side of the bearing bore so the insert can seat all the way in. That could probably be done with a dremel tool as it doesn't need to be precise.

Looks like you're pretty close to completion.

A Dremel is sending a boy to do a man's job where most engine work is concerned. My 22K RPM electric die grinder that uses 1/4" shank tooling would get the job done quickly and accurately, though. You're welcome to share those pics with your high-priced "machinist" if you choose to do so!
Jerry

My bad, Jerry, using the term "dremel" as opposed to die grinder.

I just ordered this cutter- - - -it will handle doing the chamfer, quickly and accurately. I just noticed that it's a left hand cut- - - - -I'll use a reversible variable speed 1/2" drill motor to drive it!


www.ebay.com/itm/122565152534?

Jerry

Don’t forget the key ways in your arbor! And, when are you getting a hoz mill to do this work?
Looks like a good solid setup and can be mobile.

Don

I'm using a milling attachment on my lathe and a Woodruff slot cutter in a 3 jaw chuck or a spindle collet to cut keyways. Neither one of my two Bridgeports is in operating shape right now. I've got a new apprentice on the way who says he wants to learn engine machining- - - -(Evil Grin!!!!!)
Jerry

Hope that new apprentice is not a north eastern Yankee. He may be hard to teach and make a decent Cobologist out of.


Don

Welllll- - - - -he was a pretty good student of rifle and pistol cartridge reloading- - - - - -hasn't blown off any fingers yet! I've got lots of faith in his potential!
LOL!
Jerry

Got the crank out of the 55 235 today, it looks very good! Next step will be tearing down the 41 216 block. Hopefully Jerry’s machining fixture will be ready soon and maybe his new apprentice can bring it to Southern Maryland.

Are the 216 rods and 235 rods different length? And if so, by how much?

A 216 stroke is 3.75” and 235’s, 3.94”

Rods are the same length. Gleaned from the appropriate Vehicle Info Kits: Rod length 235 6.81 inches vs. 216 6.8125 inches. Essentially the same. Per Jerry and my rough measurements, the crank to deck height is about 1/8 inch more on the 235 to account for the increased stroke.

Hey! I thought I was first in line for Jerry's machining fixture.

Don't trash that 235 #3 main bearing cap. I believe it can be fitted to the 216 block, which means only the block, not the cap, will need to be machined. I'll need to do some measuring to confirm that, and usually swapping main caps necessitates a line bore job- - - -something most machine shops don't want to do on a stovebolt engine with four different main bearing diameters. "Stay tuned!" I have a line bore machine, and I'm not afraid to use it, BTW!
Jerry

235 stroke is roughly 1/4 inch longer. Rods are the same length. 216 deck is about 1/8 inch shorter.

To use 235 crank and rods in a 216…then you’d need a piston roughly 3/8 inch shorter in compression height?

Is that about how it works out?

JW51, yes, the Buick 215 pistons have a compression height (pin center to piston crown) of 1.843 versus 2-1/16 inch for 216 pistons. By my calcs, that puts the Buick piston crown about 1/16" below the deck using a 235 crank. I'm probably going to need to regrind the 235 crank, so will see if they can offset grind it for just a touch more stroke to get that piston closer to the deck. A standard 235 crank could be ground 0.040 undersize, which would raise the piston 0.02" if offset ground.

If you haven’t already purchased the Buick pistons, might take a look at pistons for a GM 2.8L V6. A bit more compression height than the Buick. Might work out about right. Fairly affordable, too

My Silv-O-Lite piston catalog says the V6 piston is a LOT shorter- - - -1.599 vs 1.843. The wrist pin is too big, also. The best choice is the 90.5 MM Diesel piston, which can be machined to zero deck height.
Jerry

Disregard my suggestion. I must have read something way wrong. Delete my post if need be.

Just an update on the piston issue. I talked with Egge Machine and they have 1950 Chrysler pistons that will fit in 0.080 oversize, which is about 0.015 oversize for a 216. My block is standard bore with fairly minimal taper, so this will work out pretty well. Wouldn't work with a block that's more than 0.010 oversize. They'll come less than 1/64" proud of the block deck and come standard with 0.859 diameter piston pins, so I sent them a set of 216 pins (0.866 dia) to them to have them fitted into the pistons.This works for me without a lot of machine work. I'm not equipped like Jerry is and have to farm that out.
Working on plumbing a Melling M29 pump into the engine. It's inlet and outlet seem quite different from the M11 pump that the 216 uses. Jerry has said it'll take some creative plumbing to do that, so I'll put my plumbing t-shirt on to tackle that task. Just getting into that.

Sounds like fun! I just received a set of Japanese Diesel pistons that look like they can be adapted to a 216 with a 235 stroke by fitting bushings into the wrist pin holes. Those wrist pins are 1 1/16" diameter, which will allow a lot of leeway on compression height by offsetting the pin hole in the bushings, and the piston crown is around 1/2" thick- - - -so I can do a lot of whittling there if needed. The pistons weigh a LOT less than a cast iron 216 piston, even with the heavy duty Diesel construction factored in. Fun stuff! I just ordered some custom length H beam connecting rods for a big block Chevy to adapt to some of the stroker engines I've got on the drawing board.

Kevin- - - - -you could send Schneider Cams in San Diego a good 216 core and get them to put a 261/Corvette lobe on it, or get somebody to turn the bearing journals down on a Melling CCS-1 cam to fit a 216 block. Either way, you'll have a slightly hotter cam to go with that extra displacement.

Are Melling CCS-1 cams available again?

Intermittently, apparently. It looks like the Elgin cam is long gone, though. If a new Melling CCS-2 hydraulic cam happens to be in stock somewhere, it could be used as a core to regrind for a solid lifter lobe.
Jerry

Jerry, I'm not looking to soup this thing up that much, just make it more dependable without spending a boatload of money on it. Besides that I sent my spare 216 cam core to you. LOL!

I did some more checking on the oil pump replacement, and found that the drive shaft is outboard on the 216 pump, but inboard on the M29. Also, the M29 inlet is on the opposite side from the 216 pump, which would make using the original pickup assembly bolted to the main cap REAL hard to pipe to, snaking around the pump. Fortunately, I have a pickup assembly from the 58 235 that can be adapted. The oil nozzles in the 216 pan will be gone, so no issues with clearance there. When I get further into it, I'll post a thread with some pictures of the conversion.

HMMMM- - - -here's the pump I was suggesting. It's a direct replacement for the 216 pump- - - -just has longer gears and more volume. It's a bolt-in swap on any of the stovebolt engines with a straight oil pan rail on the passenger's side.

www.partsgeek.com/dhk5krk-chevrolet-bel-air-oil-pump.html?

Jerry

That's the one I got Jerry. The Melling M29 that was listed for a 53-54 235. I looked at Fannin's pic of his 1955 235 here and it has a pickup similar to the '58 235. '55-58 both use an M45 pump, but it would interfere with the oil pan on a 216. Either the M29 and the M45 both "drop in" to the block, but the ports are very different. I'll post some pics up in a few days.