LS5 vacuum " T" for K19

[Mike E.]

Attached is a picture of a metal T that I have now seen on several original 72 LS5 cars. On p. K19 A3 of the 72 AIM it is called out as part number 3760758. My 70 and 71 AIM's have no K19 sections in them, so they don't call that out in anywhere I can find. The JG has no mention of this T.
My questions are:
1) What year/s other than 72 was this used?
2) Why does the 72 AIM have a K19 section, and 70 and 71 do not?

[Joe L.]

Re: LS5 vacuum " T" for K19

Attached is a picture of a metal T that I have now seen on several original 72 LS5 cars. On p. K19 A3 of the 72 AIM it is called out as part number 3760758. My 70 and 71 AIM's have no K19 sections in them, so they don't call that out in anywhere I can find. The JG has no mention of this T.
My questions are:
1) What year/s other than 72 was this used?
2) Why does the 72 AIM have a K19 section, and 70 and 71 do not?

Mike-----


According to GM, the 3760758 as a component of the air injection reactor system was used only for 1972 Corvettes for something related to the spark control tube. However, the 3760758 tee was primarily used for windshield wiper/washer systems. As far as Corvette applications go in the latter regard it was used for 1970-71 Corvettes.

For 1970 and 1971 the AIR system was only used for LT-1 and LS-6 Corvette applications. So, the AIR installation instructions were included with the engine option UPC. There was no need to include it separately. For 1972, AIR was much more widely included. However, it was not part of federal emissions with the base L-48 engine, so it is not shown in the UPC 6 section of the AIM. That means it would need to be shown elsewhere. Strangely, though, the K-19 section in the 1972 AIM applies only to LS-5 installations which were all equipped with AIR for 1972. Consequently, the AIR installation could have been shown in UPC LS-5 and the separate K-19 section should have applied only to the base engine. Why didn't that happen? My guess is that smog control installations were in a state of "flux" for 1972 and what went into the AIM that we have a copy of may have reflected that uncertainty. There might also have been revisions to the AIM that are not reflected in our copy. For example, it may be that, initially, the LS-5 was to be available both with AIR (California emissions) and without AIR (federal emissions). That would explain why the K-19 section for LS-5 was in the AIM but still would not explain why there was not a K-19 section for L-48.

Another strange and unique factor that may have come into play for 1972 is the fact that the LS-5 was not available in California. However, it was available in the other 49 states. All of these were equipped with AIR. Note that there were 3,913 Corvettes built for 1972 with LS-5 and 3,912 Corvettes built for that year with K-19. The closeness of those numbers implies that the K-19 system was considered "optional" for LS-5 even though it wasn't really optional (except, possibly for ONE car).

By the way, the GM #3760758 tee was discontinued in April, 1977 and replaced by GM #6272766. The latter is still available from GM to this very day. It's most likely plastic rather than metal, though.

[Mike E.]

Re: LS5 vacuum " T" for K19

Joe,
thanks for the very helpful response. Where was that T used on 70-71 wiper/washer systems? I've not run across that, but I'm a bit of a novice there. Thanks!

[Joe L.]

Re: LS5 vacuum " T" for K19

Joe,
thanks for the very helpful response. Where was that T used on 70-71 wiper/washer systems? I've not run across that, but I'm a bit of a novice there. Thanks!

Mike------


I don't know where it was used but GM says it was so-used. It may have been part of a hose harness assembly so it might not be found in the AIM.

[Monte M.]

[Mike E.]

Re: LS5 vacuum " T" for K19

Monte,
I find that the square portion is right at .375 on all three dimensions. The tubes that come out are .250 where they exit the square. I'm not guaranteeing that those Ts are original, but thinking they are because I've seen them on three pretty original LS5's (all 72's).

[Monte M.]