73 Thermostat Housing Correct Part Number?

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

Lyle,
My housing has the little hole on the tab for the carb spring.

[Russ S.]

Re: 73 Thermostat Housing Correct Part Number?

Jimmy, Our cars were both built the same day!!! They are brothers. Does your 660 have the tab that Lyle is talking about? Also, does it have a date? The picture Joe posted is dated 2C. Lyle, Yes mine does have the tab and is dated 2C for I assume March of 72. It appears to be original with patina to match the rest of the engine. Just a small spot of paint left on it. This car,(1owner 23,000 miles) has one other anomaly on it. The alternator which the original owner says has not been changed has a correctly dated 1100934 37 amp on it. I know 72 used a 37 amp on some cars. I have no doubt that it is the original. If it had been changed which the original owner says it hasn't, it would have been shear coincidence that the date would match as the original owner didn't care about numbers and dates. He was and is not an NCRS member. PS I see 74 also used this alternator according to the JG and the parts book.

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

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

Jimmy, Our cars were both built the same day!!! They are brothers. Does your 660 have the tab that Lyle is talking about? Also, does it have a date? The picture Joe posted is dated 2C. Lyle, Yes mine does have the tab and is dated 2C for I assume March of 72. It appears to be original with patina to match the rest of the engine. Just a small spot of paint left on it. This car,(1owner 23,000 miles) has one other anomaly on it. The alternator which the original owner says has not been changed has a correctly dated 1100934 37 amp on it. I know 72 used a 37 amp on some cars. I have no doubt that it is the original. If it had been changed which the original owner says it hasn't, it would have been shear coincidence that the date would match as the original owner didn't care about numbers and dates. He was and is not an NCRS member. PS I see 74 also used this alternator according to the JG and the parts book.

Russ,
How about that, they were both born on the same day! But, what makes you think they were brothers? LOL, I've been referring to mine as she. Ex. She sure is pretty isn't she? I guess they could be brother and sister.
Yes, mine has the little tab. I just ran down to the mechanic's garage to see if the housing looks like the photo Joe posted. Mine does not have those deep areas Joe mentions. Mine is just flat around the bottom flange. I didn't notice or look for a date. I guess this means that mine is a replacement???

[Russ S.]

Re: 73 Thermostat Housing Correct Part Number?

Not so fast Jimmy!!! Mine also is flat around the base. I believe they are correct to our 73s at least. I know some feel they shouldn't have the spring tab however, think about this. My base motor 66 has this exact thermostat housing with the tab except it has the recesses as pictured in Joe's picture. Now if housing with tabs weren't installed on 73s, why are they correct per the JG for my 66? The tab isn't used in 66 either.

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

This makes me feel better. You pose a great question.

[Joe L.]

Re: 73 Thermostat Housing Correct Part Number?

Russ,
How about that, they were both born on the same day! But, what makes you think they were brothers? LOL, I've been referring to mine as she. Ex. She sure is pretty isn't she? I guess they could be brother and sister.
Yes, mine has the little tab. I just ran down to the mechanic's garage to see if the housing looks like the photo Joe posted. Mine does not have those deep areas Joe mentions. Mine is just flat around the bottom flange. I didn't notice or look for a date. I guess this means that mine is a replacement???

Jimmy------


I suppose it's possible the configuration of the base on the 3877660 changed by 1973. I thought it was MUCH later than that but I really can't say, for sure, just when it occurred.

[Joe L.]

Re: 73 Thermostat Housing Correct Part Number?

Not so fast Jimmy!!! Mine also is flat around the base. I believe they are correct to our 73s at least. I know some feel they shouldn't have the spring tab however, think about this. My base motor 66 has this exact thermostat housing with the tab except it has the recesses as pictured in Joe's picture. Now if housing with tabs weren't installed on 73s, why are they correct per the JG for my 66? The tab isn't used in 66 either.

Russ-----


I have never seen a GM #3877660 which did not have the triangular tab on the base for the accelerator return spring. Of course, it's unused on ALL Corvette applications. In fact, the GM #3972128 is functionally the same as the 3877660 EXCEPT for the accelerator spring tab. It was not necessary for GM to ever offer the 3972128 in SERVICE since the 3877660 would SERVICE any application originally using the 3972128. The 3972128 did not even exist until early 1970 so it could not have been used on any 66-69 Corvette. After the 3972128 was released, it or the 3877660 would have been interchangeable for any application which did not require the accelerator return spring anchor point.

I've never really figured out why GM ever released the 3972128. There just couldn't have been that much savings generated by omitting the accelerator spring tab, especially when you consider that there were not that many applications not using the tab. No application I know of used the 3877660 or the 3972128 after 1973.

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

Joe,
This is what is so confusing to me (a newbee to the NCRS) about using the JM for reference to make sure of correct parts. The 73-74 JM lists the correct part number for the 73 SB as 336790, which on everyone that I've looked up has a port on top, either open or with the plumbing plug. The last sentence in the JM about the housing states "the thermostat housing does not have a boss o port in either year". Isn't that contradicting? None of us so far have even mentioned having this 790 on our 73's, yet the manual says we should. Also, there is no mention in the JM of a different number used on the 74's which is also confusing since you state that you know of no other application of the 128, or the 660 after 73??????? Yet as mentioned earlier if our cars are judged with the 660 we will get a deduction because the manual says we should have a the 790. YIKES!!!!

[Harmon C.]

Re: 73 Thermostat Housing Correct Part Number?

What year was that JM made? That is why judges sometimes have knowledge of the errors and don't take the JM as correct. Their are lots of errors in the old JG but it is all we have.

[Jimmy P.]

Re: 73 Thermostat Housing Correct Part Number?

1999 with an addendum spring 2000