The Stovebolt Site Forums The Shop Area Engine Shop 235 main bearings

I have a 53 Chevy 3100 with the original 216 that runs but smokes and knocks. I would like to replace the 216 with a 235, I have collected 3 rebuildable 235 core engines and needadvice on which one to rebuild. 2 of the 235's are both 1955 first series truck engines. The third was pulled from a 59 belair car with powerglide. I ran it on a stand and it ran smoothly and quietly with the hydralic lifters but it smoked like a freight train. I am leaning toward rebuilding the 59 engine and using the adaptor to relocate the water pump. High performance is not what I want. I desire a stock , smooth running dependable driver. My two main questions I have are: I have heard that main bearings for the 55 first series 235's are rare and expensive and might be impossible to find in the future. Secondly, is a car engine with hydralic lifters easier to source parts for and good for a truck engine. Advice will be appreciated. George

I think the 59 is the better candidate. It has a neoprene rear main seal, as opposed to the early 55 rope seal. the early 55 also uses shims on the main bearing s where the 59 used precision bearings. It has the 848 head which translates to 8.0-8.5 compression ratio and higher horse power. The early 55 used the 5913 head which has a larger chamber and lower compression ratio, lower power. The 59 was also the recipient of the last oiling updates for the 235. So it has the better rocker arm oiling. Bearings are a little easier to find. Uses the delco remy 2403 distributor which uses tune up parts that are easier to find. Starter motor uses the later style solenoid which is again easier to find. The block is drilled for hydraulic lifters which means you can use hydraulic lifters or 56-62 261 truck solid lifters.

Any engine builder with a few brain cells to rub together can fit the later model main bearings to the early engine block in less than an hour, with no precision machining involved. All it takes is a Dremel tool with a 1/8" wide grinding stone and some careful measurements. No, line boring the block is NOT required. Forget about "rope VS neoprene" oil seals- - - -have the back of the block machined for a SKF #38647 full circle lip seal and forget about rear main bearing oil leaks. That process works on all the stovebolt engines from the 216 to the 261- - - -same seal and machining. There's also a way to modify the engine block and the crankshaft to run main bearings for a small block 400 Chevy V8, but that takes some VERY creative machining that most shops refuse to attempt. RUN- - - - -do not walk away from a hydraulic camshaft- - - -the lifters that are available these days, regardless of brand name, are all made offshore, and they have a horrendous failure rate. Original cams and solid lifters can be reground by any of several shops, and they're 100% reliable.

Changing the bore , stroke, connecting rods, and pistons can turn that 235 into a 270, BTW.
Jerry

The 55 1st and 2nd along with earlier 235s' main bearings are pinned in the block. This makes it a real hassle should you ever have to change the mains with the engine in the truck. That said, you will have to address the longer and lower water pump on the 59 block. Which is worser? I've had to deal with both and I'd rather not deal with either but I think the fan issue is harder. Once you buy a set of main bearings you can forget about it, depending on how old you are. As Jerry said you have have either block machined to take the full-circle lip seal.

As I said, it's a very simple procedure to adapt the later model bearings to the early block. The bore diameter in the block is the same, and all that's needed to run the newer design bearing is to grind a divot at the parting line to accommodate the tab on the upper bearing. The lower bearing still has the locating dowel with a corresponding hole in the cap. Oil clearance can be adjusted with shims on the older engines with either design of bearing.
Jerry

I appreciate all the good advice so far. I had previously discounted the idea of using my early 235 cores thinking that I would never find main bearings. I think I need to pull apart the lower end of one of these to visually see the pinned main bearings and imagine the fix for using the later bearings. Hope I dont need an 80 year old motor rebuilder to make the switch. At this point, I think I need to pull the heads off all 3 cores to examine the bores to check for future boring. If I choose the 59 powerglide engine, I think I should replace the cam and hydraulic lifters with solids even though it wan smoothly on the stand, just smoked. One final thought: My first core of choice is one of my first series 235's. I bought this motor from the owner of a low mileage all original 55 first series pickup. He had brought it to a restoration shop that I was working in in the summer months. He wanted us to instal a 350 small block. I ran the 235 before I pulled it and it sounded great witn no smoke. When I took off both radiator hoses, I figured all coolant had drained sufficiently. Three years later after the motor had been stored in my garage, I pulled the plugs and lubed the cylinders with mystery oil and cranked the motor with a breaker bar. I was surprised to reach a stiff spot in the rotation followed by coolant being belched from number 1 sparkplug hole. I suspect a cracked head. I must have been wrong in assuming that all coolant had drained by merely pulling both rediator hoses. Will probably need to resleeve #1 cylinder if choosing this block.

I'm not 80 yet, but I'm sneaking up on it- - - - -I'll be 78 in late April of this year! If the rebuilder you choose wants to discuss the procedure, all it takes is a phone call. I'll be glad to walk him through the block modification. The early blocks, including 48-53 216s and 235s, have a dowel built into the upper bearing shell and a corresponding divot in the block casting. The later model 235 bearings move the locking device for the upper bearing shell to the parting line between the block and the cap so the upper bearing can be rolled out of the block without lowering the crankshaft nearly an inch. The lower bearings kept the built-in dowel pin as a locator all the way to the 1963 model year.

Hang onto that smoking, knocking 216- - - - -it can be built into a 258 cubic inch engine with a stroked 235 crankshaft with pressure-lubed rod bearings and aluminum pistons for a Buick (Land Rover) 215 V8. I'm also working on building a "216" with a roller cam and roller rocker arms that should produce around 150 HP or more, and look like it's completely original from the outside.
Jerry

That smoking knocking 216 was so worn out that at some point someone had brazed shut the vent holes on the top of the valve cover, probably to direct blow bye away from the firewall. I'm 68 and remember back in the 60's that nobody pulled a motor from one of these for a rebuild, A rebuild consisted of pulling the head, grinding the valves, honing the cylinders and new rings, I suspect my motor is knocking from piston slap in cylinders that were probably never bored but just honed and rerung several times. Your main bearing description of the dowells and divots sounds like a way to keep the bearing from being spun,

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Jerry

Just a slight addition to the main-bearing discussion: Besides the earlier 235 engines, 54 and 55 Ist *and* 2nd production I6s had the main-bearing shells pinned to the block (at least the trucks did). I have a 55 2nd 235 truck engine with the block-pinned mains. It also has shims and a 2-piece lip seal (yes, it leaks-- but not too bad). I also have a '62 261 with a 2-piece lip seal. It also leaks --but not too bad.

Small block Chevy 400 V8 main bearings can be made to work with a stovebolt block, but it's not an easy job. Both block and crankshaft modifications are involved. Those bearings are dirt cheap and plentiful, however, and they can be used to salvage a "worn out" crankshaft that would have to be scrapped otherwise.

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Jerry

The engine running smooth and smoking might be something as simple as disintegrated valve stem seals

The valve cover with the vents brazed shut is a common solution to keeping water from pouring out of the cowl vent hose straight into the crank case. It doesn't necessarily mean the engine had a blow-by gas problem. Make sure the oil cap is vented, however.

If the 59 is running smooth but smoking, then the cam and hydraulic lifters were in good shape. To reuse them, just keep track of where each lifter is located and return that same lifter to its respective lifter bore. The GM hydraulic lifters were of very good quality. A regrind on an original cam core is $150-180 plus shipping. New Solid lifters are in the 120 range. A new timing set is like 50-60. So at the low end $320. Money for more important work, bearings, pistons, rings, valve job? so mayb e you scrub up the cam and lifters, coat with cam break in lube and reuse the parts.