440 six pac 3/8 crank pulley bolts question

[Ron Malmsten]

Wonder why i have 3/8 crank pulley bolts on my 1970 440 Six pack dampener i noticed the bolts off a 383 Hp were to small - 5/16 can't find any reference to 3/8 bolts being available to purchase! anyone know something about this ?

 

[pnora]

Wonder why i have 3/8 crank pulley bolts on my 1970 440 Six pack dampener i noticed the bolts off a 383 Hp were to small - 5/16 can't find any reference to 3/8 bolts being available to purchase! anyone know something about this ?

Sounds like someone drilled and tapped for 3/8.

 

[1 Wild R/T]

Yup. should be 5/16-18

 

[RemCharger]

You'd have problems with the bolt heads hitting the center of the balancer hub I would think. Maybe an arp small head would work.

 

[Lefty71]

The pully mount portion of the stock balancers is surprisingly thin, and a very brittle material (cast). They strip really easily, and I see a lot with Heli-Coils. Not surprised at all to see someone tap out to 3/8 in a home-brew situation. Six-pack damper is somewhat rare, especially compared to a plain thin damper, so I can see why someone went to some trouble to save it.

 

[Cranky]

Main problem with striped out threads is someone that likes to use gorilla torque on a 5/16ths cap screw.....if one is afraid of them coming loose, put a dab of Loc-tite on them then torque them to what a 5/16ths cap screw should be which isn't much for a fastener that small.