Balance Weight?

I removed this balance weight from the crankshaft of a 454. This was mounted between the flywheel and the crank. On it is stamped "454 Flyweel Side". Seems like the balancing could be done with the flywheel. How do I know if I need this?

Must have been a 454. The 454's are all externally balanced with a weight on the balancer at the front and a lump on the flywheel too. That weight makes me wonder if GM came up with a warranty thing to replace a 427 internally balanced engine with a 454 and not have to buy a new flywheel/flexplate.

If you have a 454, and it's not been internally balanced, you need that weight. Take a look at the harmonic balancer- on the back the inner ring will have a hump in it. Internal balance engines the ID of the balancer is round.

Tim, The engine I took this off of is a 74 454 with an external balance HB and a GM flywheel (casting #3789733). I'm guessing that this fly wheel was probably on a 427 (internally balanced)? So, guessing again, you would need this to use a 427 flywheel on a 454?

Is a 454 flywheel different than a 427?

YES-

The 427 IS different than the 454- You wouldn't want use a 427 on a stock454 unless that's what you had sitting around...

Here's a pic of a LS5 454 part #3973457




What you have sorta looks like this- for the 383-400 SBC

http://www.speedwaymotors.com/S-B-Chevy-Balancing-Plates,3262.html

Richard

BBShark said:

I removed this balance weight from the crankshaft of a 454. This was mounted between the flywheel and the crank. On it is stamped "454 Flyweel Side". Seems like the balancing could be done with the flywheel. How do I know if I need this?

Click to expand...

Not sure, but I think that is used to internally balance the crank. You could there for use a zero balance flywheel imo.

I remember seeing the same thing for the one piece seal SBC cranks.

Should really ask the engine builders as I have only limited knowledge of BBC.

Richard454 said:

YES-

The 427 IS different than the 454- You wouldn't want use a 427 on a stock454 unless that's what you had sitting around...

Here's a pic of a LS5 454 part #3973457




What you have sorta looks like this- for the 383-400 SBC

http://www.speedwaymotors.com/S-B-Chevy-Balancing-Plates,3262.html

Richard

Click to expand...

Interesting pattern on the flywheel bolts there, showing the outline of that balance plate having been used with it, in spite of the obvious casting with the weight added in the same general area, but not precisely the same area from what I can see, seems strange...:surrender:

Richard454 said:

YES-

The 427 IS different than the 454- You wouldn't want use a 427 on a stock454 unless that's what you had sitting around...

Here's a pic of a LS5 454 part #3973457


Richard

Click to expand...

Richard, It looks like (from your pic) that the weight at about 11:30 in your picture is missing on my flywheel. My flywheel looks symetrical and would indicate that the flywheel I have is for a 427 and the plate was added to convert the flywhhel to external. Here is a picture of my flywheel without the weight and with it. Looks like the weight is also at 11:30.

Thanks, looks like the mystery is solved

Exactly. Richard's picture of the 454 external balance flywheel shows the added weight. Using a 427 internal balance flywheel required adding that plate.
IIRC, there is also one for the SBC so you can use an older internal balance on a 400 that is external.

What does that 427 flywheel weigh? GM had one for the L-88/ZL-1 that was around 12-15 pounds. They did one for the LS-7 (BB) that was about the same weight.

TimAT said:

What does that 427 flywheel weigh? GM had one for the L-88/ZL-1 that was around 12-15 pounds. They did one for the LS-7 (BB) that was about the same weight.

Click to expand...

28 pounds!