73 Thermostat Housing Correct Part Number?

[Jimmy P.]

I am in the process of having my original intake manifold and carb re-installed on my car. It currently has an edelbrock performer series intake, and an edelbrock carb on it. I have been repainting everything chevy orange. While cleaning my thermostat housing to repaint I checked the part number to see if it is correct. The part number is 3877660 which I believe (thought) to be correct for all 68-73 small blocks. It is stamped on the the neck not on the flange. However, once again I found something different in the JM for the 73-74. The JM lists the part number as 336790. (pg. 78). I doesn't even list a number for the 74. Should the 74 be 469519? I checked in all the vendor catalogs and everyone of them list the correct part number for the 73 housing as 3877660. Do I have the correct thermostat housing on my car?

[Edward J.]

Re: 73 Thermostat Housing Correct Part Number?

Jim, does AIM list the part no. for your cars housing. Judging manuals are not always correct, did the JM spell out L48/L82 for the housing? there is a 73 expert, Lyle Chamberlain, maybe he will see your post. or you can PM him.

Jim just noticed there is a post below in similar threads, check them out. Lyle answered it below

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

Jim, does AIM list the part no. for your cars housing. Judging manuals are not always correct, did the JM spell out L48/L82 for the housing? there is a 73 expert, Lyle Chamberlain, maybe he will see you post. or you can PM him.

Jim just noticed there is a post below in similar threads, check them out. Lyle answered it below

Thanks Ed,
I didn't see anything in the AIM, maybe the housing was already on the engine. I did check out the older posts and I guess now I need to search for another housing. Lyle usually responds to my 73 posts. I might just PM him to make sure.
thanks.

[Harmon C.]

Re: 73 Thermostat Housing Correct Part Number?

I had a 73 judged at a Regional in Mars PA. and one of the few deductions I received was for a 3972128 as the manual said 336790. I had 5 73's at the time 4 L-48's and a 454. I checked them all and all 5 had 3972128's. At that time the team leader agreed that the 3972128 was a correct housing but said more checking needed to be done on how the 336790 got in the manual. We are using the same manual today.

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

So should I just leave mine alone for now, or try to find the 128? There's a few on ebay now? This sure gets discouraging at times.

[Joe L.]

Re: 73 Thermostat Housing Correct Part Number?

I had a 73 judged at a Regional in Mars PA. and one of the few deductions I received was for a 3972128 as the manual said 336790. I had 5 73's at the time 4 L-48's and a 454. I checked them all and all 5 had 3972128's. At that time the team leader agreed that the 3972128 was a correct housing but said more checking needed to be done on how the 336790 got in the manual. We are using the same manual today.

Lyle-----


I don't think that ANY 1973 Corvette EVER originally used a GM #336790 thermostat housing. The 336790 thermostat housing has a fitting for a temperature switch (usually for EGR) and, although 1973 did use EGR, it didn't use this switch. If the 336790 was ever installed on a 1973, the fitting would have to have been plugged with a pipe plug. I HIGHLY doubt this was ever done.

Either the 3972128 or the 3877660 could have been used on a 1973 Corvette. Either is functionally identical as far as a 1973 Corvette is concerned. The primary functional difference is that the 3972128 lacks a triangular extension on the base used for some applications for the throttle return spring. This feature is unused for any Corvette application.

The 3972128 was never available in SERVICE. It was a PRODUCTION-only piece. The 3877660 was used in PRODUCTION and available in SERVICE for many years.

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

Guys,
thanks, I'm just going to stick with my 660. This would surely be addressed in the next 73-74 JM update. In the last update they did agree that the number could be on the flange or the neck of the housing.

[Harmon C.]

Re: 73 Thermostat Housing Correct Part Number?

Lyle-----


I don't think that ANY 1973 Corvette EVER originally used a GM #336790 thermostat housing. The 336790 thermostat housing has a fitting for a temperature switch (usually for EGR) and, although 1973 did use EGR, it didn't use this switch. If the 336790 was ever installed on a 1973, the fitting would have to have been plugged with a pipe plug. I HIGHLY doubt this was ever done.

Either the 3972178 or the 3877660 could have been used on a 1973 Corvette. Either is functionally identical as far as a 1973 Corvette is concerned. The primary functional difference is that the 3972178 lacks a triangular extension on the base used for some applications for the throttle return spring. This feature is unused for any Corvette application.

The 3972178 was never available in SERVICE. It was a PRODUCTION-only piece. The 3877660 was used in PRODUCTION and available in SERVICE for many years.

The correct 73 part is 3972128 for all engines I have no idea what a 3972178 is.

[Joe L.]

Re: 73 Thermostat Housing Correct Part Number?

The correct 73 part is 3972128 for all engines I have no idea what a 3972178 is.

Lyle-----


That was an error on my part. 3972128 is the correct part number. I've corrected it above.

[Joe L.]

Re: 73 Thermostat Housing Correct Part Number?

Guys,
thanks, I'm just going to stick with my 660. This would surely be addressed in the next 73-74 JM update. In the last update they did agree that the number could be on the flange or the neck of the housing.

Jimmy------


I think it's very possible that the 3877660 was originally used for some 1973's. However, if it was used, it will be the style pictured below. Note the casting "wells" on the base adjacent to the bolt bosses. Later SERVICE examples of this housing did not have these. If yours is of that type, it's definitely not original to the car.

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

I can't open the attachment Joe, says it's invalid?

[Joe L.]

Re: 73 Thermostat Housing Correct Part Number?

OK, let's try this again. I know the photo was there at least for awhile. I don't know what happened.


DSCN0634.jpg

[Russ S.]

Re: 73 Thermostat Housing Correct Part Number?

My Sept 72 73 has the 3972128. My one owner 73 built April 30th has the 3877660. They are both L82 cars. The later car has only 23000 miles.

[Harmon C.]

Re: 73 Thermostat Housing Correct Part Number?

My Sept 72 73 has the 3972128. My one owner 73 built April 30th has the 3877660. They are both L82 cars. The later car has only 23000 miles.

Russ Does the 3877660 have the tab and hole that just peeks out above the top hole in Joe's picture?

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

My Sept 72 73 has the 3972128. My one owner 73 built April 30th has the 3877660. They are both L82 cars. The later car has only 23000 miles.

Russ,
My car is an April 30th build date also, and it has the 660.