454 flywheel size question

[Gusaroo]

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?

[pat mccarthy]

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

[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..

[NTFDAY]

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.

[Gusaroo]

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?

[Henry Rifle]

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

[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

[pat mccarthy]

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

[Gusaroo]

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...

[NTFDAY]

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

[Gusaroo]

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"

[NTFDAY]

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.

[lt1s10]

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.

[Henry Rifle]

He showed both sides of the flexplate, and I don't see any weights either. Sounds like a "be careful" to me.

[pat mccarthy]

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