Early 1970 LS5 Water Pump Question

[Greg Y.]

I have an early 1970 LS5 Vin 00504 built on Jan 9 1970. The car currently has a 3856284 water pump casting on it, I can't read the date on this pump. The TIM/JG states that the car should have the 3940960 pump casting on it. I was wondering if such an early car would have the 284 casting on it versus the 960.

Thanks, Greg

[Joe L.]

Re: Early 1970 LS5 Water Pump Question

I have an early 1970 LS5 Vin 00504 built on Jan 9 1970. The car currently has a 3856284 water pump casting on it, I can't read the date on this pump. The TIM/JG states that the car should have the 3940960 pump casting on it. I was wondering if such an early car would have the 284 casting on it versus the 960.

Thanks, Greg

Greg-----

All 1970's should have the 3940960 as later 1969's have it also. The 3856284 is, by far, the most common short leg big block waterpump casting. It was used from 1965 through 1968 for ALL Chevrolet big blocks as well as 1965 to earlier 1969 Corvettes. The later short leg castings, starting with 3940960 are, primarily, Corvette water pumps. So, there were a lot fewer of them made.

If one buys a rebuilt waterpump for a 1965-74 Corvette, there's a very good chance that a GM #3856284 will be in the box. I strongly suspect that's how this casting got on your engine. If you remove it (or, just remove the pullies so you can see the casting date), I think you'll find a date which will not "work" for your car. If you do check the date, let us know what you find.

[D S.]

Re: Early 1970 LS5 Water Pump Question

I'm glad someone else posted this. A friend pulled his January 1970 LS-5 engine for detail work and minor repairs and found the same 3856284 water pump on his so perhaps an owner before him had replaced the "960" pump, too. Or maybe that was the pump of the day before the "0960" was available in very early build '70 Corvettes. The down side is the "960" pumps are now tough to find unless you can get one from Bill Mock at Mockauto@aol.com

[Greg Y.]

Re: Early 1970 LS5 Water Pump Question

Joe,

Thanks very much for your excellent explanation!

Greg