Harmonic Balancer/ Serpentine Conversion

CorkyE

Veteran Member
Lifetime Gold Member
Nov 4, 2004
11,654
Ringgold, GA
Motors are ran on test stands all the time, no converter, no problem. Is the new balancer for internal balance engine? External balance will have an extra chunk of metal in the inner ring where internal balance will be smooth all the way around. The only factory original sbc to use external was the 400cid. That's not to say you don't have some weird crank with different requirements. My 385 with Scat crank uses an internal balancer with external flexplate. Good luck.
 

marcos beltran

Veteran Member
Jan 24, 2011
115
alvin. texas
Motors are ran on test stands all the time, no converter, no problem. Is the new balancer for internal balance engine? External balance will have an extra chunk of metal in the inner ring where internal balance will be smooth all the way around. The only factory original sbc to use external was the 400cid. That's not to say you don't have some weird crank with different requirements. My 385 with Scat crank uses an internal balancer with external flexplate. Good luck.
Im worried about the convertor making contact with the flywheel when engine is turned on. Cause i aint putting my hand down there to keep them separated, lol.
 

CorkyE

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Lifetime Gold Member
Nov 4, 2004
11,654
Ringgold, GA
You have a flex plate, which isn't going to flex, unless something is really wrong. If it was that bad, you should know it by now. You should be able to slide the converter back into the transmission a bit, 1/2" should do the trick. Someone who's done that recently should chime in. If you still have a vibration, you need to verify if the flex plate is internal/external balance. External will (unfortunately) have a weight welded to the inside.
 

djorgensen3

Veteran Member
Oct 15, 2009
876
Peoria, Az
I started my engine up several times with the converter unbolted. It will be fine. Just push the converter back toward the trans as far as it will go and let er rip!
 

marcos beltran

Veteran Member
Jan 24, 2011
115
alvin. texas
A little update. Ended up being some severe drone from my exhaust system. I had dual magnflows and they caused some crazy vibration. Made the car run like crap during accleration. Made me question if something was wrong with my engine. Replaced the maganflows with dynomax super turbos and fixed the problem. Well atleast that problem. Fixing that let me realize i now may have a problem with my transmission. Getting a whining noise when in gear and accelerating.
 

CorkyE

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Lifetime Gold Member
Nov 4, 2004
11,654
Ringgold, GA
I have dual Magnaflows with a X pipe and no droning sound. Unless they were internally constricted, I don't understand how the mufflers would affect acceleration.
 

marcos beltran

Veteran Member
Jan 24, 2011
115
alvin. texas
I have dual Magnaflows with a X pipe and no droning sound. Unless they were internally constricted, I don't understand how the mufflers would affect acceleration.
This is on a 61 impala bubbletop with an x- frame. There was no space for an x or h-pipe. The mufflers didnt literally affect the acceleration on the engine. Engine worked fine, but made it seem as i had other issues. The more i accelerated the more vibration i got. It was really bad. Made it seem as something was out of balance.
 

CorkyE

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Lifetime Gold Member
Nov 4, 2004
11,654
Ringgold, GA
Understand - post a pick of the bubble top. Brother had a 61 bubble, red 2dr hardtop Belaire. Been kicking himself for selling it.
 

marcos beltran

Veteran Member
Jan 24, 2011
115
alvin. texas
Understand - post a pick of the bubble top. Brother had a 61 bubble, red 2dr hardtop Belaire. Been kicking himself for selling it.
Still a work in progress.
20201228_164913.jpg
20211217_171755.jpg
 

sandlapper

Veteran Member
Oct 9, 2020
1,194
SE CSA
Engine Vibration: '79 sbc 350
'79 350 has 2 piece rear main seal ... so it requires a neutral (no counterweight) damper and neutral flexplate. All sbc 2 pc rms flexplates are neutral EXCEPT for sbc 400 (it has a weight on it). Also, 2 pc rms BBC flexplates for 454 have a weight.

Do ensure your 79 350 sbc has No weight (neutral) on damper or on flexplate.
 




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