73 LS4 Thermostat Housing

[George W.]

The 73-74 Corvette Tech Information Manual & Judging Guide lists part number 336773 as the correct thermostat housing for a 73 LS4. Attached are two photos of a GM housing with that part number. Does this look like the correct one?

Thermostat Housing 001.jpgThermostat Housing 002.jpg

George Walker

[Russ S.]

Re: 73 LS4 Thermostat Housing

It looks correct to me.

[Jim R.]

Re: 73 LS4 Thermostat Housing

The correct thermostat housing is part number is 3972128 it has a longer bolt on one side.

[George W.]

Re: 73 LS4 Thermostat Housing

Thank you Russ and Jim for your input. Now we need a tie breaker.

[Peter G.]

Re: 73 LS4 Thermostat Housing

George..I don't know if I should be a "tie breaker", but your picture is correct and is the same part # and thermostat housing that is on my '73 LS4/454. The long bolt shaft design on one side I believe were on the later small block C3s.

Some of the one sided long shaft even had a lip or flange with a small hole for a spring coming from the carburetor linkage.

[Russ S.]

Re: 73 LS4 Thermostat Housing

The correct thermostat housing is part number is 3972128 it has a longer bolt on one side.

Jim, I have seen the 3972128 on a very original low mile 1973 L-48 automatic that I believe is original to that car even tho the JRG states that the L48 uses the same housing as the L82 which is part number 336790. I am not saying that 336790 was not used on L48s also.

[George W.]

Re: 73 LS4 Thermostat Housing

Peter, Russ and Jim, thanks for your input. Hope to have the car judged in Dallas this fall or in Florida in January.

George

[Jim R.]

designsChevroletPICT0131.jpg

[Joe L.]

Re: 73 LS4 Thermostat Housing

All------



The GM #3877660, GM #3972128, and the GM #336773 thermostat housings are 100% functionally interchangeable as far as Corvettes go. The FUNCTIONAL difference between the 3877660 and the 3972128 and 336773 is that the latter two lack the triangular shaped extension used as an anchor for the throttle return spring on some applications (but NOT Corvette). The fact that the 3877660 and the 3972128 are designed for "long and short" bolt attachment whereas the 336773 uses two short bolts does not represent a functional difference as far as Corvettes go. The differences in the casting wells on the base also do not represent a functional difference as far as any application goes.

The GM #3972128 was never available in SERVICE; it was a PRODUCTION-only piece. It would have been foolish for GMSPO to inventory this piece since the 3877660 would SERVICE every application which originally used the 3972128. I don't even know why the 3972128 was created for PRODUCTION use starting with the 1970 model year.

The GM #336773 was once available in SERVICE. However, it was discontinued without supercession in 1986. While it was apparently used in PRODUCTION for some Corvette applications around 1972-73, it was never cataloged in SERVICE for those applications. Once again, the 3877660 would SERVICE any Corvette applications originally using the 336773. So, what applications was the 336773 cataloged to SERVICE? No passenger car applications that I can find but some truck applications.

[Russ S.]

Re: 73 LS4 Thermostat Housing

Jim and Joe, Thanks for really great info.

[William M.]

Re: 73 LS4 Thermostat Housing

My unrestored 73 LS4 has 3972128

[Peter G.]

Re: 73 LS4 Thermostat Housing

My restored 73 LS4 has 336773.