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Discussion Starter #1
I have a 400 smallblock bored to 406. It has Kieth Black forged internals,extreme energy comp cam, and double pumper Holley carb. It is internally balanced and I was told that I needed to install a "porkchop" before the flywheel. Well, the porkchop is about 1 inch to big for me to use with the flywheel. What will happen if I do not use it? Do I need to purchase a smaller one? Thanks
 

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If it is internally balanced, why would you need the extra weight?
 

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i dont even use a porkchop. I use the stock flywheel and my motor isnt internally balanced either. I have well over 250 passes on it rrunning 6.90s in the 1/8. You might try bying a newer flywheel with the right number of teeth. Mine was wrong and had to get a newer one. If you arent turning over 6000 with the 400 with stock length rods then you have no worries. Anything over that use6 inch rods. I jsut have an ati harmonic balance up front (its even stock).
 

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Stock replacement flywheel here and no problems (ext. balanced)
 

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You need to listen to onovakind and get with your builder to verify your build....internal or external balance... then pick the right flexplate. Mixing flavors don't work.:)

Re the porkchop, did they also tell you to run a scalloped balancer up front?

An internally balanced 400 runs a neutral flexplate and neutral balancer.

An externally balanced one uses scalloped balancer and weighted flexplate.
 

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Discussion Starter #6
Went to my builder and I bought the right flywheel that i needed. Will pick it up tommorow and install this week. Thanks.
 

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Discussion Starter #7
Went buy to pick up the flywheel. Wrong one. Going to have it balanced to what I need.
 

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If your crank was neutrally balanced by your builder, you need a neutrally balanced flywheel and harmonic. If one of those is an externally balanced part (bias balanced) you'll have an engine wrecking vibration if you run it for long.

What aftermarket crank do you have?

It's too late now, but usually a good engine builder will ask for all three components (harmonic, flywheel, and rotating assy) and balance them together.

FWIW,..
 

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Discussion Starter #9
I was told by the builder that I needed a 400 small block flywheel so that everthing would be balanced. Well, the 400 flywheel is to big for my clutch or my starter to work. He said all that needed to be done is to balance the original flywheel the same as the 400. My flywheel has 153 teeth compared to the 168 tooth 400 flywheel. Taking both the flywheels to him so he can do what he needs to do.
 

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I would think any small block flywheel would work. I'm using the flywheel off my 302 on my 406. It was neutral balanced. The number of teeth is for starter.
 

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Discussion Starter #11
Thats what I'm thinking. I told him of the difference and he said it could be balanced and to bring it in so it can be done. Friday I will drop it off and get the motor in the car on sunday.
 

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I don't believe there's such a thing as a 153 tooth "small" fywheel that is externally balanced.

Only two Chevy engines were engineered for external balancing, the SB 400 and the BB 454. On these two mills, there's not enough room in the crank-case for a neutrally balanced stock crank, so weight is added to the flywheel and harmonic to make up the weight that would be on the crank,..if there was room.

From the factory, both these engines got the large, 14" 168 tooth flywheel with biased balancing, though not the same bias; the 400 and 454 FW's are not interchangeable.

In your first post, you say you have an "internally balanced" rotating assy which means everything (flywheel, harmonic, and crank) are neutrally balanced, or should be.

Most aftermarket 400 cranks today are neutrally balanced because it's preferred and because it's easier to balance.

If you combine neutral and biased balanced parts, you'll get some serious engine vibration.

That's why I asked earlier, what brand and model crank is in the engine? That will quickly clear up the issue.
 

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Discussion Starter #13
I dropped the flywheel off this morning to be nuetrally balanced. If I'm not mistaken I do believe I have a stock crank. I made the mistake of just guessing. Was told that the engine is nuetrally balanced when I dropped the flywheel off.The flywheel that was ordered was a nuetral balanced but did not fit with my clutch and starter. He is neutrally balancing the 153 tooth flywheel so it can be used on the 400. This is my first engine swap so I'm still learning.
 

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If you have the stock 400 crank, a neutrally balanced flywheel won't work. Save yourself some agony here. Unless there's some sort of weight adapter that's designed for SB-400 for a small flywheel (153 tooth), like the one oneovakind67 suggests above, you may have to purchase the larger bellhousing (the "621"), a 14" SB-400 flywheel, and a different starter (the one with offset mounting bolts,..tell your local parts counter you need a starter for a 396 Camaro).
 

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Discussion Starter #15
Was looking at jegs and summit and found a 153 tooth flywheel for the 400. Going to call them and see whats up.
 

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If I was you, I'd pull the sucker down and find out what I had AND then find a different Machine Shop!!

And my 406 has a stock cast 400 crank in it along w/ the short 400 rods, a GM 400 SB 11" f/w and a scalloped stock 400 damper!!

And imho, you will do yourself a BIG favor if you ebay all your 10.5" stuff and replace everything w/ 11" stuff b/c a 406 WILL put out some torque!!

I'm NOT saying the smaller stuff won't hold up, but rather you won't have to put up w/ BS like this is all..............

pdq67

PS., I have three 11" f/w's, a stock 350, the GM 400 SB that was on my 406 and an aftermarket 454 BB that's on my 496.
 
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