383 Harmonic balancer question

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Pippen

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Does this balancer look right for a 383? I’m wondering what’s the deal with all the holes that aren’t drilled all the way through. Engine has a bad vibration around 2000 rpm and up.

27F26B19-475F-45C6-9B9F-70FCE7F1567B.jpeg
 
Might try another 383 balancer like this stock one without the extra balance holes drilled in it.

Screenshot_20211024-200318_Chrome.jpg
 
Might want to check your crank to see if it is stock. Someone may have put new pistons in of different that stock weight, so they rebalanced the rotating assembly and drilling the balancer to make up the weight differences needed.

Check your flywheel too for extra holes other than stock. Or an odd shaped flex plate. 383 should be neutral balance engine.
 
Those are balance holes that are drilled in the damper when manufactured. 65'
 
I Believe someone has drill a bunch of holes to balance an
Aftermarket Rotating Assembly. If you have a stock factory weight
assembly it would be throw the engine way out of balance. I have been
around these cars since new and I have not seen a balancer drilled like that
one out of the factory.

I have a Brand New in Box Cat neutral balance High Performance Balancer
that is more reliable and safer at high RPM for a Big Block. I think it cost me
around $300. years ago. I would sell it for $85.00 plus the ride if anyone needs it
 
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Hey John, were you lurking around the Dodge tent at 10 or 11 yesterday? I swung by and didnt see anyone from FABO.
 
Be careful here. The 1971 383 non HP engines had a cast crankshaft that will be externally balanced and require a balancer to match.
 
Hey John, were you lurking around the Dodge tent at 10 or 11 yesterday? I swung by and didnt see anyone from FABO.

Yes I was there in and out with Matt from Glendora Dodge my sponsor and friend
for 40 plus years. I told a lot of stories that I do not dare post!
 
Be careful here. The 1971 383 non HP engines had a cast crankshaft that will be externally balanced and require a balancer to match.

They are easy to identify = there is a large amount of Side weight present on the Balancer.
Out of the Millions ( I think 8,000,000 of 383 ) I believe that well less than one in a hundred
had the cast crank so the are not real common. I am not sure they had the same Design and
Diameter on the snout. I have not seen one for 40 years.
 
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They are easy to identify = there is a huge amount of Side weight present on the Balancer.
Out of the Millions ( I think 8,000,000 of 383 ) I believe that well less than one in a hundred
had the cast crank so the are not real common. I am not sure they had the same Design and
Diameter on the snout. I have not seen one for 40 years.
I agree, they are remarkably different. But the OP says he has a bad vibration. I don't believe the small amount of metal removed from that neutral balancer is enough to cause a bad vibration. I could be wrong. It's happened a lot. lol
 
Another serious issue with a 50 year old balancer is that the rubber deteriorates
badly without being obvious from the outside. This causes the top to slip in relationship to the bottom ring. This causes a vibration as well AND as it slip makes the timing wildly inaccurate as the top moves in relation to the crank. I scribed line in the old days so I could see the top move. I had one actually explode on my Max wedge Car in the 60's and it made a heck of a mess and looked like a Grenade had gone off. It did it through the lights and left a crater that looked like a Land Mine went off!

If you car is fairly fast =
NHRA will NOT let you near the Track with the old stock one on your engine.

Also the Cast Cranks had a pretty large slab of a balance weight between two
of the Converter bolts near the outside of converter. Thru the 60s and 70s my Mom ran a large Wrecking yard in So Cal. I saw an awful lot of odd stuff and that
is from where most of my stock parts came from that I still have in the shop today!
 
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Another serious issue with a 50 year old balancer is that the rubber deteriorates
badly without being obvious from the outside. This causes the top to slip in relationship to the bottom ring. This causes a vibration as well AND as it slip makes the timing wildly inaccurate as the top moves in relation to the crank. I scribed line in the old days so I could see the top move. I had one actually explode on my Max wedge Car in the 60's and it made a heck of a mess and looked like a Grenade had gone off. It did it through the lights and left a crater that looked like a Land Mine went off!

If you car is fairly fast =
NHRA will NOT let you near the Track with the old stock one on your engine.

Also the Cast Cranks had a pretty large slab of a balance weight between two
of the Converter bolts near the outside of converter. Thru the 60s and 70s my Mom ran a large Wrecking yard in So Cal. I saw an awful lot of odd stuff and that
is from where most of my stock parts came from that I still have in the shop today!
Man, you lucky * junkyard" dog! How cool is that! Musta been AWESOME!!!!!!!
 
It may just be an optical illusion, but the ring on the bal hub looks thicker towards the bottom......which would require those holes to try & balance it. Usually the ring gets drilled to balance the unit, not the hub.
 
Might want to check your crank to see if it is stock. Someone may have put new pistons in of different that stock weight, so they rebalanced the rotating assembly and drilling the balancer to make up the weight differences needed.

Check your flywheel too for extra holes other than stock. Or an odd shaped flex plate. 383 should be neutral balance engine.
How do I tell if the crank is original?
 
It may just be an optical illusion, but the ring on the bal hub looks thicker towards the bottom......which would require those holes to try & balance it. Usually the ring gets drilled to balance the unit, not the hub.
Correct, typically the inertia ring is drilled to balance the damper assembly in production. Drilling the balance holes at a larger radius gives you more balance correction. As GTX John stated, those balance holes may have been drilled in the damper hub to balance the rotating assembly, has merit here. 65'
 
Correct, typically the inertia ring is drilled to balance the damper assembly in production. Drilling the balance holes at a larger radius gives you more balance correction. As GTX John stated, those balance holes may have been drilled in the damper hub to balance the rotating assembly, has merit here. 65'
I agree, they are remarkably different. But the OP says he has a bad vibration. I don't believe the small amount of metal removed from that neutral balancer is enough to cause a bad vibration. I could be wrong. It's happened a lot. lol
I tend to agree. This thing rattles my fillings out. I’m just not sure what else it could be.
 
Automatic or 4 spd ??

Cut your oil filter open, poke a hole in it with a scratch awl and open that hole up to 1/2" with a punch, then zip around the can with an aviation snips. 1" down from the gasket seal end on the filter. See what's in there. If clean go on to looking at the torque converter.

Something that is shaking that bad has got to be a miss matched external balanced torque converter to an internal balanced enging. You have extra weights slinging around there that should not be there.

Also you may have an External balanced 360 Flywheel bolted on your internal balanced 383, they will bolt to the cranks, 318, 360, 383, flywheels all bolt up to the same crankshafts.

Is this a new engine swap into an old drive line of a different car that just came up on this build. Or is it an existing drive line where the vibration just started out of nowhere ???

360 external balance flywheel:

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360 External Balance Flex Plate:
?u=https%3A%2F%2Fwww.forabodiesonly.com%2Fmopar%2Fattachments%2Fimg_20200314_132513-jpg.jpg



?u=https%3A%2F%2Ftse3.mm.bing.net%2Fth%3Fid%3DOIP.jpg


Take the weights off for internal balanced engines:

?u=https%3A%2F%2Ftse2.mm.bing.net%2Fth%3Fid%3DOIP.jpg


For external balanced engines going to internal balance flywheels:
qti-rm-531_xl.jpg


Lots of combinations to get it wrong, need to make sure you have the right combination to get it right.
 
Automatic or 4 spd ??

Cut your oil filter open, poke a hole in it with a scratch awl and open that hole up to 1/2" with a punch, then zip around the can with an aviation snips. 1" down from the gasket seal end on the filter. See what's in there. If clean go on to looking at the torque converter.

Something that is shaking that bad has got to be a miss matched external balanced torque converter to an internal balanced enging. You have extra weights slinging around there that should not be there.

Also you may have an External balanced 360 Flywheel bolted on your internal balanced 383, they will bolt to the cranks, 318, 360, 383, flywheels all bolt up to the same crankshafts.

Is this a new engine swap into an old drive line of a different car that just came up on this build. Or is it an existing drive line where the vibration just started out of nowhere ???

360 external balance flywheel:

View attachment 1715810378

360 External Balance Flex Plate:
View attachment 1715810379


View attachment 1715810380

Take the weights off for internal balanced engines:

View attachment 1715810381

For external balanced engines going to internal balance flywheels:
View attachment 1715810382

Lots of combinations to get it wrong, need to make sure you have the right combination to get it right.
It’s a auto. No weights on the converter.
 
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