ive got a '76 305 layin around and i was just wondering if i could use the crank to put it in the '79 4 bolt 350? just the bore size is different right?

 

I'm on the same track as you are...I don't see why not. I don't know for sure though, but I don't see it being a problem.

 

I believe 305 and 350 cranks share some of the same casting numbers so yes, I don't see why not.

 

this makes me a happy boy thanks guys

 

The only difference is the balance. The 305 cranks are balanced for the lighter 350 rotating assembly. You can run a 305 crank in a 350, just make sure that the rotating assembly is light. Rumour has it that the LT1 rotating assembly is about the same weight as the 305's, so you can use the crank with that.

 

balance is differant so no it won't work even if it fits. you could have it balanced and all would be well, but for waht that cost you can buy a remanufactured crank

 

It sounds like the solution is to find a set of 305 rods and pistons and have them weighed. Then if you want to use that crank in a 350, be sure the weight of the parts you're buying is lighter.
Seems like it should mainly come down to the piston weight tho, since the 305 and350 use the same rod. Or do they?
I've never bothered to compare the weight of a 305 rod vs 350.

 

Yes.

 

Some do, some don't.

Some 305s come with "X" rods. Most don't.

There's no one single kind of "305 rod" and one single kind of "350 rod". Most of the better ones are marked somehow or have other identifying features.

Right now, I happen to have a set of the GM PM rods (LT4) in my 305. I have no clue where the crank came from though; it's just some 442 casting, could have started out life as either one, for all I know.

The piston weight is largely (although not totally) insignificant to crank balancing, since pistons don't rotate.

 

Oh, sure hey. The guys in Winneconne or Omro might just bolt it in, but I wouldn't expect someone from Appleton to do it that way. Find a set of LT1 rods as previously suggested, then balance the crank for those rods. Casting numbers aside, the weights are drilled/balanced for the final application at the factory. You'll have to do the same - just try to do a better job of balancing than the factory did. I've seen a few of those '70s engines that had huge variations in rod and piston mass on the same crank. We can do much better.

 

I had some slight crank damage when I pulled the 305 apart, my dad gave me a freshly ground 350 crank to replace it. I ballanced nothing basicly just slaped the crank in and did an overhaul of the engine. Latter it got transplanted into a 90 GMC to replace the dead 4.3L. It's still running good to this day, I just wish my ex dident get it

Granted this is vise versa but it would still work. Have you checked local machine shops to see if they have any cranks for sale? Usually you can get a reground crank for under $200.

 

i take it your from WI.

i have the 350 crank, but when my friend was taking one of the pistons out, the stud on the rod scratched the journal. minor scratch, how much would it cost to get it reground and balanced?

 

Winnecon... Omro?
I thought maybe those were two of Jupiters moons or something.

Oh yes... the crank. It's possible that you could emery paper that scratch smooth yourself.
But then again if you did some serious searching, you could probably find a balanced rotating assy that has all the pieces you need, and use yours as a core.
But if you're really in a pinch for cash a polish job will probably fix it.

 

lol.

 

If thats the case $5. Run down to Walmart, go into the automotive or tool section and pick up a scotch brite pad. Cut it to match the journal size basicly 2 1/2 x 6in and work around the journal until the scratch is gone.

 

I dont believe in balancing

 

Yeah heck . . just buy some parts and slap an engine together.
Build a test stand out of 4x4s an fire that muthah up on the ground, if it runs okay then put it in your car.
If it shakes all over the place, take it apart and have it balanced.
You're prolly gonna screw something else up anyhow if it's your first build, that'll give you a chance to fix that at the same time without having to take the engine out of the car.

 

I had a 305 and a 350 crank setting next to each other, they measure up the same but the balance is waaayyy off. The 305 rods are also smaller, and of course the pistons are lighter. Now I guess you could take a 305 crank and rods, add some light pistons and make a 350 that would rev quick. HOWEVER, the 305 pieces are not known for their strength, so the trade-off may not be worth saving the weight. If you put the 305 crank in, you will have to balance it.