Correct 1964 crank pulley bolt?

[M W.]

Hi all,

With all the recent discussions regarding TR balancer bolts I decided to check the Judging Guide and see which bolts were used to secure the balancer pulley on the 64 L75 engine and there was no mention made about this that I could find. Any ideas what head style and type was used? Was a lock washer or star washer used? Flat washer perhaps?

Learning minds would like to know.

Cheers,

Craig Willetts
#36551

[Joe L.]

Re: Correct 1964 crank pulley bolt?

Craig------

GM #3815933; still available from GM (although manufacturer's headmark will be different). For 1964, I believe that an internal tooth star washer was used.

[M W.]

Re: Correct 1964 crank pulley bolt?

Joe,

Can you be a bit more specific on the original head bolt style? Thanks a bunch.

Craig

[John D.]

Re: Correct 1964 crank pulley bolt?

Craig, Very little response on this subject. Bolt should be TR grade 8 w/hole. Inside star washer. Bolt & washer are zinc or cad plated (zincad) The washer was quite unique though and was bare steel.
Over the counter replacements were or are blackened LE bolts with a cross hole. Joe says the bolt is still available but it's only a service replacement.
Cheater is to find a grade 8 TR of proper dimensions and get a good machine shop to drill the hole with a carbide bit. Won't be cheap though. Don't know the size of the hole.Might be 1/8"??
I tried to get a survey going but it didn't happen. Should do that stuff in the dead of the winter. John

[Timothy B.]

Re: Correct 1964 crank pulley bolt?

Craig,

If you are talking about L75/300HP, they did not use a bolt at this location.

[M W.]

Re: Correct 1964 crank pulley bolt?

John,

Let me make sure I understand. The same TR bolt that was used to secure the Harmonic Balancer on the 63 high power cars is the same one used on a 64 L75 300 HP where the balancer is pressed onto the crank and the ballancer pulley is secured to the balancer. Seems a bit overkill to use a safety wired bolt. I am suprised that the Judging Guide makes no mention of this. If it does and I missed please point out the page.

Thanks,

Craig

[M W.]

I am referecing the ballancer pulley on my 64 L75 *NM*

[Clem Z.]

grade 8 bolts can be drilled with regular

high speed drill bits,but not those cheap offshore drill bits

[John D.]

Re: Correct 1964 crank pulley bolt?

Craig, No it wasn't. Tim is correct for sure. Only the hiHP engines used the grade 8 drilled bolt. But I will tell you and many others will agree it certainly is a good idea to have a good bolt holding the balancer onto the crank. Many horror stories occur because of worn parts and the balancer coming loose at hi-rpm. But for originality-no it would not be correct. I think in the future it would be nice for a lot of us to just spell out the HP instead of using numbers as dummies like me don't know all the numbers. Say 300 hp or 375 HP instead of using codes such as L75 and L84. Good luck, John

[Joe L.]

Re: I am referecing the ballancer pulley on my 64

Craig-----

Somehow, I misread your original post as this being and L-76. The L-75 used NO balancer-to-crankshaft bolt.

[Joe L.]

Re: Correct 1964 crank pulley bolt?

John------

The last time I purchased these bolts from GM, the bolts I received were identical to the originals with respect to configuration except for manufacturer's headmarking. They were zinc plated, too, had the same head configuration, and were of Grade 8 with 6 radial lines.

The type of plating was somewhat brighter than the originals. However, for those that desire to re-create that "look", a little polishing with fine steel wool will "break the glaze" and get one closer to the original sheen.

[Brian Monticello]

Re: Correct 1964 crank pulley bolt?

Here's what they look like from GM.... part #3815933
brian

[John D.]

Re: Correct 1964 crank pulley bolt?

Joe, THe last time a friend of mine purchased the bolts the logo was and is LE and they were blackened. I think that we all make too big a fuss over bolts as far as which were black and which were shiney. Not referring to you but just our judging process in general. I know for a fact that Rochester Products was not that fussy with the FI's. Thanks, John

[John D.]

Re: Correct 1964 crank pulley bolt?

Brian, Thanks for the nice pic of the LE bolt. I see you and JL agree that the replacement bolt was shiney. The original TR was zincad also. John

[M W.]

Re: Correct 1964 crank pulley bolt?

Thanks so far but I don't think anyone has answered my real question as to which bolt head was used to secure the pully to harmonic balancer on a 64 300 HP car? A picture would be nice if available.

Thanks,

Craig W.