Water Pump Stud Length 69 427/400 W/PS

[Ned T.]

I'm looking for the correct stud length on the part of the stud that protrudes out from the water pump. This receives the A.I.R. Pump brace and also the alternator brace. I think my stud is too short since the nut will barely go on without a lock washer.

[Joe L.]

Re: Water Pump Stud Length 69 427/400 W/PS

I'm looking for the correct stud length on the part of the stud that protrudes out from the water pump. This receives the A.I.R. Pump brace and also the alternator brace. I think my stud is too short since the nut will barely go on without a lock washer.

Ned------


The original stud, GM #3877646, had an outer thread length of 0.90". The alternator brace is 0,200" thick, the AIR pump brace is 0.210" thick, the correct nut is 0.33" thick and the correct lockwasher is 0.105" thick. This all adds up to 0.845". So, the stud should be long enough.

Caution: GM replaced the 3877646 many years ago with stud GM #461318. It might not be exactly the same as the earlier. It's no longer available from GM, either.

[Ned T.]

Re: Water Pump Stud Length 69 427/400 W/PS

Joe,

Thank you for the information, I'm sure that didn't come easy. My stud is the wrong length so now I'll have to find one that's long enough.