Just want to make sure I order the right one!

Need a flywheel for my V8 swap.

383 (400 crank, 350 block).

I have a Centerforce clutch setup for 82-92 V8 third gens. Not sure if it's for early models (PN DF161675) or later models (PN DF161056) but specs for both seem to be identical.

So I need a balanced, 153 tooth, 400 flywheel right?

What diameter? 10.4"?

Once I pull my motor to start the swap I have no car so I have to have everything ready!!

 

If you have a stock 400 crank, or other crank with stock 400 balance, then you need a 12.8" (153-tooth) flywheel with the stock 400 unbalance. The 14" (168-tooth) flywheel will not fit in the T-5 bell housing.

Since there is no such thing AFAIK, there most certainly never was from GM in any case, you'll have to make one. Easiest way is to take a 83-85 305 Camaro/Firebird flywheel and have it unbalanced to the stock 400 spec. You will find that there are 2; one for the granny grocery cart motor (LG4) that weighs about 22 lbs, and one for the performance motor (L69) at about 16 lbs. You'll probably want to make your "special" from the light one.

Clutch will be the 10.4". Early or late doesn't matter. Can't imagine what the difference could possibly be, they're identical in every way in the car.

 

I have no idea if it's internally or externally balanced. Never could find a way to find that out. All I can go by is the flexplate that came on the motor when I bought it if that'd help me find out.

But, I was told that I can run a balanced flywheel even if it's already internally balanced I guess.

Wondering why you said unbalanced?

 

I think sofa was saying that all 400's are external balanced. Meaning if you got an internally balanced flywheel, it has to be unbalanced.

 

Ahh really? I was chatting with the Summit tech people and they said it was OK to run a balanced flywheel even if the engine was already internally balanced.

Is that not true?

And from what everyone's said, these builds are never internally balanced. But how can you find out??

 

Motor was originally installed in a plow truck.

Here is the flexplate I took off it, would this help?

Looks like it has a counterweight but is that what we're talking about here?

 

Gotta figure that out first. The flex plate that came on it is no help: might have just been put there as a handle to turn the motor with, who knows.

Is it a stock 400 crank? Start there. Identify the crank. Post the casting #.

I said "unbalanced" because a stock 400 crank requires a flywheel with about a 25 oz-in unbalance to it. Which means, the product of the oz it's unbalanced by, times the distance from the crank center that the weight is located, must equal approx. 25 ox-in. The weight must be located approximately in line with the big funky shape on the back of the crank, which is also where the dowel pin is.



Most common way of accomplishing this is to drill about 15 - 20 ½" holes about ½" deep around the opposite edge of the flywheel.

{edit} Your pic shows a flex plate with stock 400 unbalance.

 

100% sure that flywheel is what's been on the motor since it was new. It was a crate 383 special from the back of a Car Craft haha

Stock 400 crank far as I was told, yes, but I'll have to pull the pan to check. Have to get it up on a stand first... should buy a used engine picker! lol

 

just another idea. IF you have a 400 crank the most affordable externally balanced 153 tooth flywheels are heavy 25-30 pounds. on my 400 I used the stock lightweight 305 flywheel and a counter balance plate from speedway part nmbr 91615375. my machine shop guy had never seen one but said it balanced perfectly. been in there 10 years now no problem.

 

Very cool, I had been wondering about those. Good to hear some real world test experience! That'd be SO much cheaper than a custom flywheel!