[funbiz99]

not sure what happend to my first post....anyhow i have a 383 the flexplate has a weigh bolted on it but the balancer has no weights. is this internal or external balanced?? is this some kind of hybrid lol?

[DeathRattle]

It's probably external. I doubt anyone would just put weights on the fly/flex for the fun of it. It may have been a 400 crank that was turned down and that was the fly/flex that was on it before.

[fast68]

if its a 383 then it has a 400 crank and therefore it is externally balanced and furthermore will be weighted externally

the balancer wont have weight attached to it, rather it has an area of removed material on the backside, as seen here on my 400 engine:


unless someone knows something different ?

here is stock factory 400 external balance weight:



good luck

[funbiz99]

ok this is why i am still confused! there is suppose to be a forgrd scat crank. there is no material removed from the harmonic tomorrow i will post a pic. the flywheel weight does not look like it is factory installed. should i put a 400 harmonic balancer on it? i already ordered it before i noticed it was not weighted. thanks

[DeathRattle]

Technically Weight its added or removed in certain spots to balance the crank when the crank is being balanced. I would leave it the way it is for now unless you plan on taking out to be balanced. Summit or jegs won't know where to add weight or take weight away.

[funbiz99]

ok this is sorta what i was thinking. leave the 350 balancer on unless it starts to vibrate.....right?

[Richard H.]

Originally Posted by funbiz99

ok this is sorta what i was thinking. leave the 350 balancer on unless it starts to vibrate.....right?

No it should have a 400 balancer , I'm building one now and your flex plate doesn't sound right either.

[funbiz99]

Originally Posted by Richard H.

No it should have a 400 balancer , I'm building one now and your flex plate doesn't sound right either.

i agree that is what the post is about........but what is the best course of action?

[Richard H.]

Originally Posted by funbiz99

i agree that is what the post is about........but what is the best course of action?

My guess is if it is a scat crank and still has the flex plate and balancer from a 350 it was never balanced from the git go , externally or other wise. I believe the weights in the balancer are removed for a internally balanced engine and some are even adjustable.

[funbiz99]

ok then should i just put a 400 balancer&flexplate on? the engine seems to run smooth (no noticeable vibration) , if i wasn't underneath changing the exhaust i would have never noticed the weight held in by a bolt on the flexplate. at first glance i thought it was a spacer until closer inspection!

[machine shop tom]

There are 2 versions of the 383 build. One uses a 2-piece rear main seal crank and the other uses the later 1-piece rear main seal. The first one uses a flywheel AND balancer that are weighted. The second uses a weighted flywheel but the balancer is neutral.

The 1-piece rear main seal SBC's came out in 1985.

If you have the 1-piece rear main combo, then the balancer should not be weighted (aftermarket balancer) or have material removed from the backside (OEM balancer).

tom

[funbiz99]

tom this is a two piece rear main. after looking at the prices of internally balanced forged scats i would doubt thats whats in there. i have to assume its ext balanced. now i ask just put a 400 balance and flexplate???

[machine shop tom]

If it doesn't shake, why monkey with it? It would have a noticable shake if balancer andor flywheel was wrong. Without pulling it apart you can't know if it is internally balanced or not.


tom

[machine shop tom]

Originally Posted by Richard H.

My guess is if it is a scat crank and still has the flex plate and balancer from a 350 it was never balanced from the git go , externally or other wise. I believe the weights in the balancer are removed for a internally balanced engine and some are even adjustable.

If it were an untouched Scat crank it would probably shake like a working girl in a confessional.

tom

[machine shop tom]

Originally Posted by funbiz99

ok this is why i am still confused! there is suppose to be a forgrd scat crank. there is no material removed from the harmonic tomorrow i will post a pic. the flywheel weight does not look like it is factory installed. should i put a 400 harmonic balancer on it? i already ordered it before i noticed it was not weighted. thanks

Good, I'd sure like to see the weight on the flywheel.

Is it a stock balancer or aftermarket?

tom