[JEC3039]

I just finished rebuilding the original 389 from my '66 GTO, a car I've owned since Nov 1972. Engine has been dynoed, bagged and set aside, no problems.

But while going over and detailing my 389 parts, I observed that the crank pulley is p/n 9786713. A lookup in the Zazzarine/Roberts book indicates this is a '67 part number (7-5/16" dia). My '66 pulley SHOULD be 9783144 (7-1/4" dia). Not a big difference. Both are 6-bolt pulleys.

My first instinct was to find and buy a -144 pulley to make my car perfectly correct, but now I'm having second thoughts about that. My car was built in June 1966, right on the verge of the '67 model year. Since I've owned the car, I've never fussed with any of the engine frontal parts (timing cover, water pump, harmonic damper, nor any of the pulleys). And I doubt the guy before me would have had any reason to change out the crank pulley in the first six years of the car being built. So I'm wondering if Pontiac ran low on -144 pulleys at the end of the '66 build and pulled ahead usage of the '67 -713 pulleys? Can anyone comment on whether you've seen pullaheads like this?

Thanks -

[6d7gto]

Pretty sure I have an NOS pulley with dampener set up. Can't remember what year/application or what numbers are stamped into the pulley. Will need to check my storeroom then get back to you.

[unruhjonny]

if that is the part that's been on your engine since 1972 when you first got it, I'd leave it as-is.

That's just my opinion.

[hgerhardt]

It probably came with the '67 pulley as original. My '66 GTO (Fremont) was built 5th week July '66 and came with several '67 parts. LH inner fender with the bigger recess for the '67 brake booster, shoulder belt anchors, THM400 bolt holes in the frame (but with open-ended upper spring pockets), and a few other details I can't remember at the moment. Bought the car from the original owner in '87 and it hadn't been touched, ever. Original paint and 87k miles with a seized engine (he apparently never bothered to change or check oil either).