Harmonic Balancer interchangeability???
Senior User
Joined: May 2000
Posts: 254
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From: New Baden, IL. USA!
Harmonic Balancer interchangeability???
Being very careful here as I bough a used 1977 F100 with a factory rebuilt motor that had about 12,000 miles on it.
To make a long story short, the motor had a rumble in it that came and went. Not a bearing sound, and several good friends/mechanics had no idea.
Well....crank broke between the first 2 rods and the second main bearing after about 5,000 miles.
When the remainder of the crank was pressed from the balancer, it was cracked[balancer] where it attached to the crank.
The heads are rail type, so they should be '77 vintage.
I had the machine shop order a replacement balancer and the box says 80 and up. That is what matches the #s on the old one
What are the differences in the harmonic balancers between '77 and '8X??? The crank I got is from a '77. Regrind w 10 under grind.
I'm wondering if a slight difference in the balancer might have caused the problem. The motor ran well before and did not have any noticeable vibration.
Any suggestions are greatly appreciated! Thanks.
To make a long story short, the motor had a rumble in it that came and went. Not a bearing sound, and several good friends/mechanics had no idea.
Well....crank broke between the first 2 rods and the second main bearing after about 5,000 miles.
When the remainder of the crank was pressed from the balancer, it was cracked[balancer] where it attached to the crank.
The heads are rail type, so they should be '77 vintage.
I had the machine shop order a replacement balancer and the box says 80 and up. That is what matches the #s on the old one
What are the differences in the harmonic balancers between '77 and '8X??? The crank I got is from a '77. Regrind w 10 under grind.
I'm wondering if a slight difference in the balancer might have caused the problem. The motor ran well before and did not have any noticeable vibration.
Any suggestions are greatly appreciated! Thanks.
Senior User
Joined: Jun 2000
Posts: 458
Likes: 1
Harmonic Balancer interchangeability???
I've re-read your post a couple times and if I missed it I'm sorry.
Do you have a 302 or 351?????
If it's a 351 there is NO difference in inbalance in any of the years.
If you have 302 and a 1980 balancer it should be compatable with the '77 crank. Ford changed the balance in '81 and ABOVE 302's to 50oz imbalance. Check your flywheel/flexplate also.
Anything up to an '80 on a 302 should work. '81 and above is a different game.
351's are the same in all years but there's a catch!! 302 balancers and flywheels will bolt up. So, again, if you have a 351 and '81 302 stuff you have the wrong parts..
Sorry if this was confusing.
Do you have a 302 or 351?????
If it's a 351 there is NO difference in inbalance in any of the years.
If you have 302 and a 1980 balancer it should be compatable with the '77 crank. Ford changed the balance in '81 and ABOVE 302's to 50oz imbalance. Check your flywheel/flexplate also.
Anything up to an '80 on a 302 should work. '81 and above is a different game.
351's are the same in all years but there's a catch!! 302 balancers and flywheels will bolt up. So, again, if you have a 351 and '81 302 stuff you have the wrong parts..
Sorry if this was confusing.
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