School me on 235 cranks, please!

Is there a difference between the "babbit pounder" and "full pressure" cranks, other than being drilled for oil to the rods? Like, if you did the block mods to a dipper type block, will the crank from a pressure engine fit? I'd think with a pressure crank and GMC rods, it'd really strengthen up the ol' Stovebolt.

Thanks,

Jay

 

Back up,someones gotta know!

 

Main and rod journals are the same diameter according to my Federal-Mogul book.(so a drilled crank should fit).I have heard of full-pressure 216's being done, but I believe it takes alot of work.With a 235,it would probably take so much work and money,you'd spend less doing an engine thats already full-pressure.(Just my 2 cents)

 

Thanks CP, I figger if I can get a crank, then the block mods I can do myself, and all I will have to get done is the main bearing babbiting. The GMC rods have insert bearings, so that isn't an issue.

Thanks again,

Jay

 

It may not be such a lot of work,now that I think about it.I think the biggest think with the 216 was the crank,which you got covered. Maybe a 235 oil pump,eliminate the oil distibutor valve,and of course 235 bearings.I think oil to the rockers can be left alone.I think even the dipper trough un bolts so you can use the same pan.keep us posted !

 

What year 235?

 

Actually, the MAJOR headache is gonna be pistons. That's where the money is at. The 235 has a 3/16 longer stroke, and the GMC rods are the same as a Chevy, so won't that put the pistons 3/16" higher in the bore? The GMC rods also have .990 pins, which I don't think the stock Chevy has... hmmm.

Jay

 

Why not full pressure 235 rods?, Also late 235 splash oilers had insert bearings. Back to the F.M. book!

 

Thats insert mains,I meant!

 

All 235's had insert mains,but the 48-53 ones are the same size as the later 235 full pressure ones.The 40-47's have a different O.D.,but the shaft is the same size.

 

I could use those, but the Jimmy's are beefier looking... I know it ain't no blown hemi, but... period hot rod parts

Jay

 

What size GMC are the rods from?

 

248-270...

or as they say, Group I

Jay

 

If the GMC rods are the same length as 235's than the compression height is what determines how close to the deck (or above or below)the piston ends up.in other words,it boils down to what size 235 pins are. If they're .990,you're good to go with the 235 pistons.235's have a pinch-bolt to keep the pin,what about GMC's?

 

Yes, they have a pinch bolt... they are very similar, but beefier!

Jay

 

235's are.866 dia. according to an ancient Motors manual Thats roughly 1/8" diff. IF you knew an automotive machinist that would tackle it,maybe they could be honed to .990 (yes thats a hell of a lotta honing)

 

Well, if I was using a 235, I think I could just swap cranks and use the stock stuff, but as you noted I got a 216, so I think I would have to use custom pistons anyway, because of that offset...

Thanks for your help so far, I'll look into pistons in the am!

Jay

 

The 235's are .866 according to an ancient Motors manual. If you are on good terms with an automotive machinist,maybe you could get 'em honed out There's about 1/8" difference, thats a helluva lotta honing

 

Sorry for double posting. It was a long day shoveling snow around here!

 

Yeah, we got lucky and haven't got any snow, yet!?

Jay

 

Now THIS is a hard-core trad rodder!

The dude has a small block Chevy on an engine stand in his garage, and he's planning a 216 build!!!

You ROCK!!!!

(Besides....who ELSE would I off the dead motor back to???)

 

Nope the GMc and Chev rods are different.

in order to use the GMC rods in a chev 6 you must narrow the bottom end to Chev width bearing size.

GMC rods are 7" long with a 0.990 pin.

chev rods are 6.7" long with a .866 pin, so Buick v6 pistons are used with a 261 block (3.75" bore) and GMc rods. And ther 265" SBC has the same bore as a 235" 6, and I think (repeat think) it has the same compression height. Chev six cylinder pistons have an offset pin of about 0.078" so beware of the type of piston you use in this combo.

 

Interesting, cause according to "California Bill", the Group I rods are the same size rod and main throws as a Chevy,you just need special pistons. As you can tell, I don't have any of the parts but the 216. I need to get some for "side by side" comparison. Thanks for the info so far. This place is great.

Jay

 

By the way you can fit a full pressure 235 crank into a 216 dipper block if you want to modify the 235 to fit. If anyone wants the how-to-do I'll find Dick Bertilucci (sic) response to the same q that I got from him over 10 yrs ago.

 

All I gotta say is "HELL YEAH"

Please?!

Jay