3 bolt vs 4 bolt harmonic balancer - Vintage Mustang Forums
 
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post #1 of 8 (permalink) Old 03-20-2009, 05:15 PM Thread Starter
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3 bolt vs 4 bolt harmonic balancer

I have a 70's 302 in my 66 and I'm trying to put the correct crank pulley on the car.
It has power steering and is supposed to be a 2 groove 6 1/8" pulley.
The problem is that my 70's balancer is made for a 4 bolt pulley and the correct pulley is a 3 bolt.
I can't find the right size pulley in a 4 bolt.
Can I replace my balancer on a later 302 with a correct one for a 66 289?

66 fastback, 302, T5, 380 gear (Yeah, I call it a fastback)
69 Camaro restomod, ZZ3, 700r4, 4.11 Moser 12 bolt w/Eaton posi, Wilwood 4 wheel disc brakes
(No, I don't call it pro-touring)
72 Camaro, gathering parts for restoration
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post #2 of 8 (permalink) Old 03-20-2009, 05:19 PM
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Re: 3 bolt vs 4 bolt harmonic balancer

As long as your 302 has a 28 oz imbalance and not the 50 oz imbalance you will be fine. In the 70's they were still 28 oz imbalance as far as I know so I dont think that you will have a problem...maybe someone else will chime in here to confirm.

~Ryan~

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1969 Mach 1- 357w: 11:1 compression, ported Canfield heads, FTI billet solid roller cam, Vic Jr., 850 Mighty Demon
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post #3 of 8 (permalink) Old 03-20-2009, 05:51 PM
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Re: 3 bolt vs 4 bolt harmonic balancer

I went through the same thing not long ago.My 302 was out of an 84 so it was a 50oz balance with 4 bolt.I ordered one with 28oz 3 bolt from summit racing.I think 74 is when they went to 50oz balance but I cant remember for sure.
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post #4 of 8 (permalink) Old 03-20-2009, 06:37 PM
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Re: 3 bolt vs 4 bolt harmonic balancer

Quote:
Originally Posted by ymurf
I went through the same thing not long ago.My 302 was out of an 84 so it was a 50oz balance with 4 bolt.I ordered one with 28oz 3 bolt from summit racing.I think 74 is when they went to 50oz balance but I cant remember for sure.
Not quite sure what you are saying here?..If your engine was a 50oz balance why did you order a 3 bolt 28 oz balancer?...Also the change was made in balance in late 1981...


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post #5 of 8 (permalink) Old 03-20-2009, 08:54 PM Thread Starter
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Re: 3 bolt vs 4 bolt harmonic balancer

So if the change was made in 81, then I should be safe installing the 28oz 3-bolt balancer from a 66, right? Since my 302 is from the 70's.

66 fastback, 302, T5, 380 gear (Yeah, I call it a fastback)
69 Camaro restomod, ZZ3, 700r4, 4.11 Moser 12 bolt w/Eaton posi, Wilwood 4 wheel disc brakes
(No, I don't call it pro-touring)
72 Camaro, gathering parts for restoration
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post #6 of 8 (permalink) Old 03-20-2009, 09:38 PM
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Re: 3 bolt vs 4 bolt harmonic balancer

Quote:
Originally Posted by frdnut
Quote:
Originally Posted by ymurf
I went through the same thing not long ago.My 302 was out of an 84 so it was a 50oz balance with 4 bolt.I ordered one with 28oz 3 bolt from summit racing.I think 74 is when they went to 50oz balance but I cant remember for sure.
Not quite sure what you are saying here?..If your engine was a 50oz balance why did you order a 3 bolt 28 oz balancer?...Also the change was made in balance in late 1981...
Sorry,Thats what I meant.I had to order a 3 bolt 50oz balance so I could run the original 289 pullys.
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post #7 of 8 (permalink) Old 03-23-2009, 12:54 PM Thread Starter
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Re: 3 bolt vs 4 bolt harmonic balancer

TTT

66 fastback, 302, T5, 380 gear (Yeah, I call it a fastback)
69 Camaro restomod, ZZ3, 700r4, 4.11 Moser 12 bolt w/Eaton posi, Wilwood 4 wheel disc brakes
(No, I don't call it pro-touring)
72 Camaro, gathering parts for restoration
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post #8 of 8 (permalink) Old 03-23-2009, 08:13 PM
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Re: 3 bolt vs 4 bolt harmonic balancer

You should be fine...just to be sure you could double check the casting number on the balancer to confirm its a 28 oz balancer.

~Ryan~

http://i164.photobucket.com/albums/u...DSCF0139-1.jpg
http://i164.photobucket.com/albums/u...1/DSCF3667.jpg
1969 Mach 1- 357w: 11:1 compression, ported Canfield heads, FTI billet solid roller cam, Vic Jr., 850 Mighty Demon
Full manual AODE transmission w/ 9.5" Art Carr converter; 4.11 detroit locker

http://www.cardomain.com/ride/2554478
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