Thread: 454 flywheel size question

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This is my first BBC, so I am full of questions...

I have an 84 454 out of a C30 towtruck. It came with a 12" flywheel / clutch set up. I plan to use a smaller gen 3 camaro bellhousing so I believe a flywheel, clutch and pressure plate swap is in my future. My question is about the balance? Is my engine internally or externally balanced? Can I just purchase another smaller flywheel? What do I need to be looking for?

Anyone looking for a 12" set up and want to swap?

you need a 454. if that is what you have. the fly wheel that is externally bal any thing that a 454 from the year you have .the 5-6 mark 454 and a diferent weight do not try a 400 small block or a internal fly wheel you will beat it to death

Pat, Not sure I follow... What you are saying is that I should stick with only 454 flywheels...? Any other chevy flywheel (though it may fit) should not be used...?

When you mention the mark 4 and 5 454, I am confused..

The flexplate on a 400 sbc and the flywheel from a 454 bbc are externally balanced. To my knowledge eveything else in Chevy's inventory is internally balanced.

Originally Posted by Gusaroo

Pat, Not sure I follow... What you are saying is that I should stick with only 454 flywheels...? Any other chevy flywheel (though it may fit) should not be used...?

When you mention the mark 4 and 5 454, I am confused..

mark 4 is on it own 4 is the only one for a 454 that will work and mark 5-6 are not the same as a mark 4. i would not use one of them cheap plates .they all will bolt up but just not bal to your engine the mark 5-6 one pice rear seal so they have no counter hub for add weight gm makes a#3963537 for a 1970-90 outside dia 12.3/4 and #3993827 fro 1970-90.11 clutch outside dia 14. ,gen5-6 #1409687 454/502 11clutch and nodular iron #14096805 the weight i am talking about is the counter or bob weight on the wheel not the same on a 454 from 1970-90 to mark 5-6

This may be a dumb question, but are they externally balanced and matched to each motor, or will a flywheel off one 454 work fine on another 454?

Also, I have seen "flywheel balance plates" for the 454, so I could use any flywheel. Sounds hokey, anyone ever use one?

454 Flywheels are not matched to the motor at the factory. You can interchange. I've never used a "balance plate."

Thx guys, I think I have all the info I need for this one, time to hit ePay...

btw, here is one of those "balance plates" I mentioned...fyi
Clickee here

Originally Posted by Gusaroo

Thx guys, I think I have all the info I need for this one, time to hit ePay...

btw, here is one of those "balance plates" I mentioned...fyi
Clickee here

i have run one. carried it to the man that did my bal. along with the crank, flywheel, pistons and rods, when i got it back he had added a lot of weights to it. worked ok . for the st. i wouldn't be scared of it.

Originally Posted by lt1s10

i have run one. carried it to the man that did my bal. along with the crank, flywheel, pistons and rods, when i got it back he had added a lot of weights to it. worked ok . for the st. i wouldn't be scared of it.

that great but would you just bolt one on ? if he added to it then there a good bet that it will not work to good with out any work to it . i have run a bal. machines and you would be better using the right wheel . for the 454 if you are not going to take it all apart to bal .you can rebalance it and put heavy metal$$$$$ in the back counterweight you can run any internal fly wheel or buy a new crank that as more counterweight to run a internal damper and fly wheel

Originally Posted by pat mccarthy

that great but would you just bolt one on ? if he added to it then there a good bet that it will not work to good with out any work to it . i have run a bal. machines and you would be better using the right wheel . for the 454 if you are not going to take it all apart to bal .you can rebalance it and put heavy metal$$$$$ in the back counterweight you can run any internal fly wheel or buy a new crank that as more counterweight to run a internal damper and fly wheel

for the st. i might. i always like to bal. my motors, so it was something i didn't have to decide on.

If the 454's are externally balanced, do they even make non-externally balanced flywheels for the 454? The reason I ask is that I am looking at a nice aluminum flywheel for a 454, but the owner doesn't know if it is extenally balanced. It looks to be symetrical with no weight castings or abnormal holes drilled in it. Here is a pic


Now that I posted this, I hope fellow CHR'ers don't start bidding on this now...

That flywheel will not work. There have to be counterweights on the back side of the wheel.

Now the guy just emailed me... and I quote him as saying:
"it is a externally balanced- on the inter side is a balanced weight, i personally ran this flywheel in my car"

Have him send you a picture of the backside of the flywheel and compare the weights to flywheel from an internally balanced engine. There is quite a difference.