Size of huge cam nut on harmonic balancer?

[Guess]

Does anybody know the size of the big cam nut on the harmonic balancer? Is it 28mm? Taking a guess. O'reilly's says they can't order that size. Thanks.

 

[BIGPSI]

i think it's an 1 1/8 "

 

[forzfed]

It's 28mm but a 1 1/8" will work, just a tad loose.

 

[Guess]

Thanks guys!

 

[Nick Micale]

It's 28mm but a 1 1/8" will work, just a tad loose.

I think you have that statement backwards! :biggrin:

This is the same bolt used on Buick V-8's from back in the 60's, and the designation on the head signifies SAE grade 5. I have yet to see GM use a SAE bolt with a metric hex head?

My 1-1/8" sockets have worked on thousands of Buick crank bolts, and probably a 28mm will work too.

I know north of the border, metric is more common up there, but some of us here still have trouble wrapping our brain around this "metric thing", especially on the T-R's when both SAE and Metric fasteners were mixed?

Among my favorites are bolts that are SAE on one side, and the hex/stud threads are metric on the other side.

 

[forzfed]

Maybe it's my Canadian car.:biggrin: I used the 1 1/8" as well, but I did find the 28mm was a nicer fit, not that it matters much at that size.

 

[Guess]

I assumed it was metric. In any event, the 1 1/8 was a little loose, but a cheater bar and bumping the starter loosened that baby easily!