Put a 400 crank in my 383 block?

[RRSweden]

What to do...?

Having my forged crank removed and inspected I reallise I'll have to let the shop work on the bearing journals at a cost I don't know...

A guy is selling a 400 cast crank in good condition for a good price (about 100 dollars)

So... First of all, does the 400 crank fit the 383 engine? And what do you think I should choose? I'm building a street-car and aiming for 350-400HP...

 

[Claytonhc]

I'd be interested to know this as well. Ibe heard a 440 crank will fit in one also

 

[RRSweden]

Yes, but that crank has longer stroke I know for sure..
I will re-use my rods and pistons so, I need a crank with the same stroke.

 

[Claytonhc]

Yes, but that crank has longer stroke I know for sure..
I will re-use my rods and pistons so, I need a crank with the same stroke.

Oh ok cool. Yea I thought you where trying to make a stroker

 

[Cranky]

The 383 will accept the 400 crank but since the 400 crank is lighter than the forged unit, you should have it balanced to the rest of the assembly.

 

[RRSweden]

Oh, that's a bummer I guess... So what parts would I need to change to make it balanced?

 

[1778ppr]

The 400 crank will fit mechanically into a 383 no problem. Same dimensions. However, the 400 crank is probably cast and therefore externally balanced. The 383 is probably a forged crank and internally balanced. The cast and forged cranks use different harmonic balancers and the torque converters. The cast cranks have weights on the torque converter. Do you have a manual or auto trans? If manual you will have to “internally “balance the crank (read expensive) and then use the forged type vibration damper. If auto trans you just need a “cast” vibration damper and a weighted flex plate so you can use your current TQ.

I just went back and re-read that you have a forged 383 crank. Still if you have an auto there is no problem and installing the 400 cast crank will be relatively low cost. You will just need a damper and flex plate.

 

[dvw]

Balance job will cost more than the crank. What is the problem with the 383 crank? Machining a crank around here is less than $100. What are you doing with the engine? A stock running 383 is pretty cheap as well.
Doug

 

[RRSweden]

Just weighing my options... I have a manual transmission.

Thanks for all the answers! (as you might understand it's the first time I'm rebuilding an engine)

It all sounds like I'm better off having the shop work om my forged 383 crank bearing journals, buy oversized new bearings and keep the balancer.

Again, thank you for sharing your knowledge!
I'll keep posting questions, be shure...