The Stovebolt Site Forums The Shop Area Engine Shop Rebuilt 235, but has sat

I recently acquired a large lot of 57-62 235 engines/parts, one of which is this rebuilt one. However the previous owner who had it built let it sit and it caught some condensation, (I lightly honed the cylinders to clean them up, but it will need to be disassembled and further cleaned up, the crank journals will at least need a good polishing.

If you have the rest of the "short block" (new pistons, reconditioned connecting rods, etc.), assuming the crankshaft doesn't have to be reground again to clean up the rust pits. There's a LONG way to go from where it is now, to being a running engine. Most re builders want to do their own machine work or have it done, not trust somebody else's efforts. A block that's been bored and honed properly has the piston skirt clearance fitted to each individual piston by precision honing.
Jerry

For me, the challenge in buying something like this is that I don't know who did the machine work. Reputable machine shops won't bore and do the final honing without new pistons in hand. Since you honed them to remove surface rust, I have to figure out if the clearance is now still within tolerance for .040 over pistons.
Sad to say but this block and crank should be considered a pig in a poke deal if I am a buyer.

Sad to say but I agree. Since the engine can't be guaranteed the buyer is accepting any risk done by prior work .

1955first 6500why dont you buy a .002 12 inch feeler gauge and seeif piton clearance is close,then see if main brgs are good on clearence with plastigage or steel shim if OK scrub with HOT water and soap,take your mains out for washing,clean the rod throws -up then offer it for inspection. Any mechanic can evaluate it that way. when its scrubbed air hose it dryall throughout, it will turn brown if really clean .then bag it to keep clean ! you'll have to take the cam out too.

That crank does not look like a polishing will do the trick. I think that one will need to be reground.

The rod journals are already .020" undersize. One more regrind, and its next use will be to hold up somebody's mailbox.
Jerry

dragsix when Iran the crankshaft grinder circle racers would bring in rusty SBC shafts and have them polished for clearance I disn't like it but they were paying so i done what they said and it worked.

A brand new race engine has more clearance everywhere than a 100K mile street engine. That's why we run thick oil and high volume oil pumps to keep up with the leaks past the sloppy loose bearings. Doing race engine stuff on a street engine that's expected to last more than a thousand miles or so before it blows up or gets freshened up is beyond stupid.
Jerry

Everyone to their own of course but rebuilding one of these old Chevys is not cheap these days. Why on earth you would want to take a chance on a bad journal is beyond me. Can it be polished and made to work, I guess it can but just because you can does not mean you should. By the look of that crank, those pits go pretty deep. Cut it clean and you have the best chance of not having trouble. I have a 261 with a .030 crank (rods and mains) in it and I run it to 5800 rpm. Five years of abuse and not a moments problem. Those cranks are made of pretty good material. Couple that with a stock motor that rarely goes over 3800-4000 rpm, going to .030 or further is no problem. I would not hesitate to run one of these cranks at .040 maybe even as far as .060 for a pure stock motor. But like I said, every one to his own.

Dragsix You always hope for a 10-10 shaft they wouldn''t make the bearings if they wouldn't hold-up. Vincennes indiana had a lot of undersize journals that done a lot of work. Big stuff too ! Had a 6-71 come in that you handle wifh a chain hoist.

I agree. If I had my druthers, .010 on rods and mains is pretty good. But those cranks can go way further and you can get bearings for as much as .060.

NASCAR engines run rod bearings in the 1 7/8" diameter range at 9K+ RPM and over 600 HP. The size of a bearing journal is pretty much immaterial, as long as the oil clearance is right and the oil pump can supply enough lube to keep the metal parts suspended on a film of oil. If anything, smaller diameters of bearing journals are better, because the slip speed of the surface of the bearing is lower, making the job the lubricant has to do less stressful.

It's possible to bore the big ends of Babbit lined rods for an insert bearing. Instead of using the scarce and incredibly expensive dedicated bearings that have been available for decades, I've found that a rod bearing for a Perkins 3 cylinder Diesel has the right outside diameter, but the crankshaft journal needs to be ground .060" undersize to fit the bearing. The upside is that the bearings cost about $5.00 each, and several undersizes are available that would allow further regrinding of a shaft that would need to be scrapped otherwise. The stroker crankshafts I'm working on to dramatically increase the displacement of stovebolt engines are also using sub-2" rod bearings.
Jerry

Hey Jerry, what are your thoughts on the Chevy small block cranks, why did GM increase the diameter of the journals in the late 60's. Just curious if you did any research or instruction on that topic.

I believe they did that as a method of making some parts interchangeable between several engines and car lines. For instance, the 292 6 cylinder runs the same connecting rod journal size and rod bearing as the big-journal small block Chevy crankshafts. We used to make 3 9/16" stroke small blocks by offset-grinding 350 crankshafts and using the small journal connecting rods and pistons with a shotrter compression height. A lot of parts sharing between engines, and even car lines began in the mid 1960's, about the time the 3rd. generation Chevy six came along. The 4 and 6 cylinder Chevy engines even got the same bellhousing bolt pattern as the V8's, and automatic transmissions got dual pattern bell housing bolt circles so Chevy and Buick/Olds/Pontiac car lines could share transmissions. About the same time, GM consolidated the engine production to eliminate duplications between the engineering departments of the individual car and truck lines. I believe it was all a cost-cutting effort to make GM a more efficient auto maker. At one time, Buick, Olds, and Pontiac all had different 455 cubic inch engines, and Chevy had a 454. Not exactly a good way to control costs, but each car line had independent engineering and R&D departments.
Jerry

Dragsix On those polished SBC shafts that was 50 yrs. ago,cheaper then , plenty of 327 cranks in the weeds !!

Not sure you meant that for me.

Dragsix Dirt tack racing was a lot more cheap fun when you could slap one together for Saturday night,starting friday night !!

dragsix Yes that was for you,lets build one --you drive it !!