Will a 350 crank from a ls1 work in a 90 block?

 

No
Completely different engine

 

Thats what I figured. The counterweights must be different.

 

Completely different engine

Nothing from a LS engine fits into a reg SBC ( except the valve springs)

 

Bummer.

 

the lifters are interchangeable, and i think you can use the lifter retainers from an early LS engine in a late gen 1 small block, if you think you'll need to change the cam without taking the intake off or something..

 

This is a total rebuild. Picked up a complete '90 350/TPI that I intend to put in my '89 that currently has a 305/TPI.

When I tore the 350 down, it had 3 spun rod bearings and the crank is most likely shot.

I have a lead on a crank that came out of an LS1 motor and was only wondering if it would work.

Gonna keep looking for an earlier model crank...

 

Also remember there are differences among the same generation cranks too: balancing (internal or external) and rear seal (1 piece or 2 piece).

Depending on what you want to do buying a complete Cast *cringe* or Forged assembly is easy enough.

 

just find another stock 350 crank.. maybe take yours to a machine shop and see if it can be saved.

 

why not just use your 305 crank since they are the same?

 

Use the crank from my 305 in the 350? Hmmm, hadnt thought of that.

Had no intention of tearing the old 305 apart, really figured I'd build the 350, once complete and ready, pull the 305 and only take the accessories I needed and drop the 350 in. The 305 is still my weekend driver.

The stroke, rod journals and main journals are the same. There is a catch tho. My 305 has over 300k miles in the original motor. Still runs great, and holds ~35-45 pounds oil pressure (on the factury guage). It has no knocks or the tell tale sounds of worn bearings, although I can only imagine how they must look.

Anyone else ever done this...chime in. Ya have my attention now.

 

305 & 350 cranks ARE NOT "the same".

They have the same stroke, and some are machined from the same casting #; but, they are balanced differently.

Because 305 pistons are lighter, there is more metal drilled out of the counterweights of a 305 one, than the same casting made into a 350. Therefore you can make a 350 crank into a 305 one by drilling more, but it's ALOT harder to go the other way.

Unless of course, you use SIGNIFICANTLY lighter pistons.

All the same, as CHEEEEEEEEEEEEEP as cranks are, and especially stock cast ones, it doesn't make alot of sense to scab one out of a running engine.

 

Sofa....
Agreed. I did some reading and the balancing issue seems to be the biggest problem with dropping a 305 crank into a 350 block. It's a problem I dont really see the need to tackle. I'm not against dropping a little cash for a stock 350 crank. May even call the local Chevy dealership to see if they can scrounge one up. I have been surprised by what they can do, and it'll be an OEM crank.
Otherwise, I'll just find another stock crank and start from there.

 

I would just start calling around to machine shops. Sometimes machine shops that deal with racing applications have "used" parts in stock.

I'd take the block to have it checked out first at a good machine shop. They should be able to tank it, flux it, and check the walls for you. They might find issues with it. They might find it needs a bore job to clean up the walls. At that point you'd be stuck with a cast crank when if you're going that deep there isn't much purpose putting a cast back in. Aftermarket rotating assemblies are fairly cheap.

 

A NEW cast crank for a 350 is $200. Thats pretty reasonable. Otherwise I'd call machine shops and see if they have any refurb'd cranks around. Factory cast cranks arent as strong as the aftermarket ones, but if the machine shop refurb'd them, the used ones will be more likely to have the correct machinework done. A lot of hte cheap aftermarket cast cranks are machined overseas and can vary here and there with the more vital measurements. Definitely fixable, though.

Of course... your stock crank is likely fixable too, depending on how badly damaged the journals are.

 

So a 305 crank is different then a 350 crank? 10-12 years ago some main bearings spun in my 305 so the engine shop rebuilt the bottom end of the engine and rebuild the heads. I just recently pulled the engine and tore it down and got the cast number on the crank he put in it and the cast number is 14088526 which according to a search is a 350 crank on summit. Is that wrong, or is it actually a 350 crank since he put it in aftermarket?

 

Same raw casting (therefore same casting number), different finished crank.

 

*sigh*

 

I think I saw cast cranks in summit racing for around $180. Like I said though if you have the block tested and everything and need to go as deep as pistons, rods, and etc. At that point I wouldn't even bother going with doing a OEM cast assembly. You could pick up a master rebuild kit even if it was aftermarket cast fairly cheap. I only paid around $300 or so for my Eagle 4340 Crank off eBay from some race shop out on the west coast. Course then it had to be reground to 350 mains but I was expecting that and it was still cheaper than going with a 383 crank.

 

Hmmmm

Another option. Called a local T/A shop and they mentioned another option.

He says they have LT1 setups and they will drop right in to the L98 block. They have LT1 cranks rods and pistons that I can buy as a set. The LT1 setup has lighter rods, lighter pistons and the crank is balanced for those rods/pistons.

Anyone ever used an LT1 setup in a pre-LT1 block?

 

Yup; drops right in. All dimensions are the same.

Crank's not worth a crap in those any more than any other stock crank, but they have nice rods.