1972 small block 3991399 to 330813 water pump changeover

[Michael C.]

Re: 1972 small block 3991399 to 330813 water pump changeover

Patrick,

My late, late, 1972 LT-1 is serial 26683, and the water pump is a 3991399 dated C 8 2. It's always possible the water pump was changed at some point, but it was on the car when I bought it in 1991.

My engine build stamp date is V0628 CKY; casting date of F 9 72.

According to Joe Lucia's post from the archives, my pump should be a 330813--with the boss and plug.

Any help here would be appreciated, since I am in the process of restoring the pump, and if it's dead wrong, I'd like to put a correct pump on my engine.



Michael

[Joe L.]

Re: 1972 small block 3991399 to 330813 water pump changeover

Patrick,

My late, late, 1972 LT-1 is serial 26683, and the water pump is a 3991399 dated C 8 2. It's always possible the water pump was changed at some point, but it was on the car when I bought it in 1991.

My engine build stamp date is V0628 CKY; casting date of F 9 72.

According to Joe Lucia's post from the archives, my pump should be a 330813--with the boss and plug.

Any help here would be appreciated, since I am in the process of restoring the pump, and if it's dead wrong, I'd like to put a correct pump on my engine.



Michael

Michael-----


My guess is it's original to the car. I seriously doubt that such a pump would have wound up on the car by sheer chance. The dates on both the pump and the engine "work" for the car. Based upon this one data point, plus a few other reports we have of late 72's with the 330813, it looks like there might not be a discrete point at which the changeover in pumps occurred. In other words, for some period, either pump may have been installed. In any event, it looks like the 3991399 pump casting was used later than we believed.

[Patrick H.]

Re: 1972 small block 3991399 to 330813 water pump changeover

Patrick,

My late, late, 1972 LT-1 is serial 26683, and the water pump is a 3991399 dated C 8 2. It's always possible the water pump was changed at some point, but it was on the car when I bought it in 1991.

My engine build stamp date is V0628 CKY; casting date of F 9 72.

According to Joe Lucia's post from the archives, my pump should be a 330813--with the boss and plug.

Any help here would be appreciated, since I am in the process of restoring the pump, and if it's dead wrong, I'd like to put a correct pump on my engine.



Michael

Thanks for the info.
As you note, it's later than I "might" expect, but it definitely helps to know this. I'll add this to my survey.
And, for now just assume it's correct.

Oh, and 330813 would be boss, no plug.

Patrick

PS I now shows 2 motors built June 28th, each with a different number water pump.