383 steel crank to 400 block

[tomfed]

what does it take to put a 383 steel crank into a 400 block what has to be changed?

[Nacho-RT74]

match the damper if forged

[tomfed]

what do you mean by damper i'm sorry i'm not a motor head i would like to put a 4spd to the 400 but it has a cast crank.

[Cooter]

Crank/Rods/rebalance bottom end if running new pistons.

[John_Kunkel]

The damper (or harmonic balancer) on the front of the crankshaft has an offset weight to provide external balance when a cast crank is used, a forged crank has no external balance so if you install a forged 383 crank in a 400 that had a cast crank you'll need a  damper for a forged crank.

You can install a 4-speed in a cast 400 crank but you'll need to drill the rear of the crank to clear the pilot on the transmission input shaft and then install a special pilot bushing in the end of the crank where the converter hub used to fit. Some folks use the special bushing and just cut off the end on the pilot but I think this is unwise. The flywheel for a cast crank also needs external balance, a neutral balanced flywheel can be easily modified to provide external balance.

[Cooter]

I would think it would be easier to just build a stroker from the 400. Either that, or find a stell crank 400 out of a truck or something.

[Nacho-RT74]

why rods ? they are the same!

oh, yes I forgot, will need remove counterweights from Torque converter ( or new 0 balanced converter ) if auto. If Manual, will require also a 0 balanced flywheel.

Stroke is a good idea but will require more money, for a while you can find a nice 383 forged crank on the cheap around ( or even new freshly machined from Rockauto on $300 rate )

[tomfed]

i see that 440 sorce has external balanced flywheels for 360-440 cast crank's.I think that would be the eaiset and cheapest way to.So what do you guy's think?

[John_Kunkel]

A steel billet flywheel is always more desireable than the factory cast flywheel so, yes, it's the best way to go.

[Cooter]

why rods ? they are the same!

Ever checked the weight on an early set of 383 Steel Rods VS a later set of 400 CAST Rods? Might be surprized.  

Just becasued they are the same length, doesn't mean they are balanced out equally from the factory. We tried this same line of thinking back in around 1993. Hadda 361 Block/pistons. Pressed 'em on 400 Cast crank rods, and used a NON extended flange 383 Steel crank and threw it togther.

Checked all clearances, looked good, so it should be ok right? No oil pressure after 500 miles. Wondered what that vibration was at around 2200 RPM.

[John_Kunkel]

Cast rods in a big block? No way, the rod used in the last 400 was the exact same "692" forged rod used in the first 350.

The only item that would make a balance difference between a forged crank 383 and a forged crank 400 is the piston and there isn't that much difference in piston weight because the 400 piston always had a lower compression height than the 383. IOW, even though the 400 piston is larger in diameter and would, therefore, seem to be heavier, it isn't because the compression height is less.

Therefore, a forged 383 crank can be swapped into a cast crank 400 with no changes except the balancer and flywheel/converter.

[ACUDANUT]

 Why not just use the 383 block. Damn good engine all around.

[JB400]

They're looking for cubes, but obviously don't have/ want a 440.  I'd take either one honestly.

[Cooter]

Cast rods in a big block? No way, the rod used in the last 400 was the exact same "692" forged rod used in the first 350.

You misread/understood John.....CAST CRANK rods. STEEL CRANK rods. So yours balanced out, that's awesome. Ours didn't..Going by personal experience.

[tomfed]

Well the reason i don't want use a 383 i have a 72 roadrunner 400 4spd car but the origanal engine is gone.A drilled 400 engine is hard to find but i have a 1974 440 cast crank engine.i might use it in stead and do the samething drill the crank and put an external balanced flywheel on it i was going to use a 400 but i got this 440 instead.

[Cooter]

Well the reason i don't want use a 383 i have a 72 roadrunner 400 4spd car but the origanal engine is gone.A drilled 400 engine is hard to find but i have a 1974 440 cast crank engine.i might use it in stead and do the samething drill the crank and put an external balanced flywheel on it i was going to use a 400 but i got this 440 instead.

SWEET! You'll LOVE the longer stroke 440. That 400 ain't even got as much stroke as a 350 Small Block Chevy.

[ACUDANUT]

383's and 440's are my favorite engines