I am building a 1977 junkyard low budget 454- rings/bearings only, new cam (227/241 duration at 0.050), and valve job. Flywheel is factory A/T (TH400) from 1977 Suburban. I bought a aftermarket torque convertor (2400 stall) that requires a "dual pattern or TH350 flywheel.

What do I do now? The 454 is externally balanced. If I buy an aftermarket flywheel it has to be a 168 tooth extenally balanced one. How do I get it to work with my parts? What do I need to get balanced?

Help!!!:(

Don't 454 externally balanced flywheels have 6 bolt holes? Are you saying you need to bolt it with 6 bolts instead of 3?

Pestwagon

Fear not
Simply get any 454 flexplate that has the both converter bolt patterns, large and small.
The flexplates for a 454, regardless of the converter bolt pattern, all bolt up and are balanced correctly for you

Weights welded to the flexplate and a large mass on the backside of the harmonic balancer, external weights/external balance help to balance the 454 engines.

I am building a 1977 junkyard low budget 454- rings/bearings only, new cam (227/241 duration at 0.050), and valve job. Flywheel is factory A/T (TH400) from 1977 Suburban. I bought a aftermarket torque convertor (2400 stall) that requires a "dual pattern or TH350 flywheel.

What do I do now? The 454 is externally balanced. If I buy an aftermarket flywheel it has to be a 168 tooth extenally balanced one. How do I get it to work with my parts? What do I need to get balanced?

Help!!!:(

http://www.jegs.com/p/Hays/757704/10002/-1

This will fix your problem ..... Jegs #490-10-020 = dual bolt pattern Hays 168 tooth heavy duty flexplate.
I bought one from Jegs in August, it cured my torque convertor/Turbo 400 bolt-up issue. nice piece, too.

So the new flexplate doesn't need to be rebalanced?

Or you can use a 350 f/p and a cheap 454 crank flange balance plate.

pdq67

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So the new flexplate doesn't need to be rebalanced?

How many torque converter mounting tabs are on the flywheel that came with the motor. If it has six it is a dual pattern and if it is good it will work for you.

So the new flexplate doesn't need to be rebalanced?
I was told, if you were going to spin the motor past 6500 RPM's regularly it probably should be re-balanced ... My engine had previously been balanced, but there had been very little weight/weld added, so I chose not to re-balance, since my cam is pretty much maxed out about 5600-5700 RPM, anyway. plus, it was about 110 miles each way, to have it done by the original engine builder, when gas was about $4.00 per gallon.

How many torque converter mounting tabs are on the flywheel that came with the motor. If it has six it is a dual pattern and if it is good it will work for you.
My stock 1986 model 454/TH400 flexplate, had only 3 holes to connect the stock 13" torque convertor ....

The Hays #10-020 has 6 holes drilled into it, (dual bolt pattern) to bolt the torque convertor to the flexplate. Coan said the new 11" Pro Street convertor had a 10 3/4" bolt circle, where as the stock GM 13" convertor, I believe had a 11 1/2" bolt circle ....

my autozone 454 flywheel has 6 holes. all evenly spaced, Not a dual pattern. I just pulled out the trusty die grinder and fitted 3 of the holes. I figured the center of the converter is registered to the back of the crank, so no worry's there. jim

Or you can use a 350 f/p and a cheap 454 crank flange balance plate.

pdq67
=
Paul
If you had ever spun one of these weights up on a balancer you would not keep telling people to do this ;)

Pestwagon Steve,

If you read my response (#3 above) closely, even casually, you'd have seen where I clearly stated
"The flexplates for a 454, regardless of the converter bolt pattern, all bolt up and are balanced correctly for you"

Each year thousands of flexplates are replaced without issue.
Do you think that you are special?
After all, this is a welfare build we're talking about here...
Been there a few times.

Or you can use a 350 f/p and a cheap 454 crank flange balance plate.

pdq67

you forgot the......................... HEHE!

OK, OK..

I'm cheap so would use one and go!

I will keep my pie-hole shut on this.

And a He, He!! for Dan.

Mike they are sold so apparently used so just how bad are they off??

Would using one w/ a 350 f/w THEN balancing be OK so that I wouldn't have to buy another 454 11" f/w and then probably balance it anyway?

pdq67

OK, OK..

I'm cheap so would use one and go!

I will keep my pie-hole shut on this.

And a He, He!! for Dan.

Mike they are sold so apparently used so just how bad are they off??

Would using one w/ a 350 f/w THEN balancing be OK so that I wouldn't have to buy another 454 11" f/w and then probably balance it anyway?

pdq67
=
HI Paul
The ones I have seen & used in stuff like bomber deals have been pretty heavy & appear to be designed that way so they can be cut down to match the assembly
I could stick a 400 flexplate on & the balance was close but when I used the plate I had to cut it
It was quite a bit of weight but you could most likely run one if all you were concerned with is a vibration you felt.
Lot's of engines out there running along quite happily that are not even close to correct ;)

But you know how I am about balance,,, :D

Thanks All!! I guess the way to go is with a new flywheel with both bolt patterns- since this is a budjet build- any recommendations?

I ended up getting an Edge torque convertor with dual pattern on it- fit the stock flywheel too. Not exactly the budget way to do it, but it'll drive WAYYYYY better now...