Torque Spec for the Harmonic Balancer Pulley Bolts??

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70DusterBob

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They are on a 1975 360. Just finished putting the double roller timing chain in. Took me for EVER!

Thanks!
 
I’ve always used 25/30lbs. Never had any issues.

Jake
 
Maybe these are accurate (can't believe everything you find on a search):

Moparts ttorque.png
 
OP, are you asking about the bolts to hold the pulley to the damper, or the big bolt for the damper to the crank? If it's the 5/6" pulley bolts, then 15-18 ft lbs. If it is the big damper to crank bolt, 135 ft lbs.
Glad you got that chain done!
 
OP, are you asking about the bolts to hold the pulley to the damper, or the big bolt for the damper to the crank? If it's the 5/6" pulley bolts, then 15-18 ft lbs. If it is the big damper to crank bolt, 135 ft lbs.
Glad you got that chain done!

Thanks, yeah, just the bolts that hold the pulley to the damper. I will set my torque wrench for 17.

Can't wait to ride again!!!
 
Torque spec is.... use a 1/4 drive ratchet and make it real tight. That's idiot proof.

Just keep in mind what size fastener you're torqing down, a sae production 5/16 won't put up with much more than 25- 30 lbs before it breaks, moly header bolts will put up with more torque than those.
 
Torque spec is.... use a 1/4 drive ratchet and make it real tight. That's idiot proof.

Just keep in mind what size fastener you're torqing down, a sae production 5/16 won't put up with much more than 25- 30 lbs before it breaks, moly header bolts will put up with more torque than those.
 

I think I double replied...

Anyway, going with Grade 8 Bolts, I believe that is what came out of them. I thought there would be a much higher torque on them than 16-18lbs, but I've gotten that from a few sources. I think it may be hard to dial that in on my 1/2" drive torque wrench, lol!!! So tight as I can get em will work and I will have to do my best to get em even if I can't use my torque wrench.
 
Here ya go.... note that plated bolts (Zinc or cad plated) get less torque, as the plating makes them slicker, and thus they will reach a higher level of stress/strain in both threads and bolt if you run them to the same torque as non-plated ones. (And oiled threads acts like plated threads...)

Tightening Torque Guide

Edit to add: BTW, the grade of the bolt is just one half of the situation... the thread stress and strain of the nut or whatever you are threading the bolt into has to be considered. If the nut (or other internal threaded objust, like your damper) is of a lower grade, then the limits on the lower grade material determines the limit. I would suspect that the damper material is more like grade 5 than grade 8.....so I would stick with the grade 5 limits. (And would also use some blue Loctite if I wanted peace of mind.)
 
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Here ya go.... note that plated bolts (Zinc or cad plated) get less torque, as the plating makes them slicker, and thus they will reach a higher level of stress/strain in both threads and bolt if you run them to the same torque as non-plated ones. (And oiled threads acts like plated threads...)

Tightening Torque Guide

Edit to add: BTW, the grade of the bolt is just one half of the situation... the thread stress and strain of the nut or whatever you are threading the bolt into has to be considered. If the nut (or other internal threaded objust, like your damper) is of a lower grade, then the limits on the lower grade material determines the limit. I would suspect that the damper material is more like grade 5 than grade 8.....so I would stick with the grade 5 limits. (And would also use some blue Loctite if I wanted peace of mind.)

Thanks so much. Although I was familiar with the cleanliness of female and male threads mating, I forgot all about using loctite to keep them in there. That is a great idea.

Thanks for the chart also, it helps!

BTW, is your nick implying "Number 9's The Ham"? I always wondered what it means, lol
 
BTW, is your nick implying "Number 9's The Ham"? I always wondered what it means, lol
Late reply.....easy answer. I'm a ham radio operator as well as a car nut, and NM9S is my FCC assigned call sign. When I first visited FABO, I had no clue it was so good so I signed in with my moniker from an antique electronics forum, not knowing I would find this site to be as great as it is. The rest is history as they say.....
 
Late reply.....easy answer. I'm a ham radio operator as well as a car nut, and NM9S is my FCC assigned call sign. When I first visited FABO, I had no clue it was so good so I signed in with my moniker from an antique electronics forum, not knowing I would find this site to be as great as it is. The rest is history as they say.....

Ohhhhhhh, well now it makes perfect sense. I couldn't figure that one out too save my life, lol? Yeah, someone told me about this place and I too had no idea it was soooooo awesome! Best thing that ever happened to me and the Duster!
 
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