Crank pulley hole alignment question

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pauls340

pauls340

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I've read before others having this problem. Stock 1970 340, stock vibration dampner and stock 2-groove crank pulley. Only 5 of the 6 holes line up. My in-family Mopar expert says that's not right; either dampner is wrong or pulley. Pulley # 3814378. I can't find if that # is correct for 1970 340's. Thanks in advance

Pulley.jpg
 
Just elongate the hole in the pulley that doesn't line up. At some point Mopar changed that bolt pattern. If these parts were somehow balanced as an assembly, orientation might matter. But they were not, and it does not. Been running my '69 340 with one elongated hole for 15 years with no issues.
 
That sure looks awfully close to the k-frame! I noticed the biscuit motor mount and it looks like it is not sitting correctly or the wrong rubber. Are you sure that is correct?
 
I am sure you already did this... You did rotate it to every hole combination?
 
69_340_GTS said:
Just elongate the hole in the pulley that doesn't line up. At some point Mopar changed that bolt pattern. If these parts were somehow balanced as an assembly, orientation might matter. But they were not, and it does not. Been running my '69 340 with one elongated hole for 15 years with no issues.
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Thanks, i've been running without that sixth bolt. So maybe the new pulley's would be misaligned also.
 
yep, forged cranks and later cast cranks are different. Just use a rat tail file to elongate the one hole, install the bolt, and carry on. The tiny amount of balance change is sooo close to the center that it can't make a difference.
 
Not sure when the change was, early offset, later even, my 67 273 has the offset.


Alan
 
Cuda Al said:
Not sure when the change was, early offset, later even, my 67 273 has the offset.


Alan
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My '69 340 pulley has the offset hole. So did the old balancer. My aftermarket harmonic balancer, which is neutral balance for the forged 340 crank, has evenly spaced holes. I don't think you'll find any aftermarket balancers for either cast or forged cranks with the offset hole.
 
69_340_GTS said:
My '69 340 pulley has the offset hole. So did the old balancer. My aftermarket harmonic balancer, which is neutral balance for the forged 340 crank, has evenly spaced holes. I don't think you'll find any aftermarket balancers for either cast or forged cranks with the offset hole.
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and that is a aftermarket "one size fits all" part. Same applies to a headlight switch. Replacement will have a tang for a ground wire whether your model has a wire to put there or not.
 
Looks like the balancer is correct for 1970, but, the pulley is a later version with the even bolt pattern that started in the '72 model year.
 
LOLOL I ran into this way back in the '70's before "Al Gore invented the internet". Of course I had no idea why and could not believe "they'd change that."
 
I don't know why they offset that one hole to begin with, unless there was some oddball model that had the timing slot on the pulley in an application where it was too hard to see the one on the balancer. :wtf:
 
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