71 LT-1 carb stud

[Robert S.]

Re: 71 LT-1 carb stud

Just checked the AIM and it shows a stock nut and no washer.Gotta take my washer off. Ed

Terry, when you put together the judging manual, I'm sure you must have addressed the discrepancy with the AIM at some point. Can you provide any quick comments on this?

[Terry M.]

Re: 71 LT-1 carb stud

Terry, when you put together the judging manual, I'm sure you must have addressed the discrepancy with the AIM at some point. Can you provide any quick comments on this?

[Terry M.]

Re: 71 LT-1 carb stud

Basic question: What are the correct finishes on the carb stud, nut, and washer? This is not specifically addressed in the TIMJG. No luck searching the archives either, but I did see a discussion suggesting that perhaps a separate nut and washer may have not been used for this year. Any further comments on this?

Academics start their search for knowledge by "reviewing the literature." Shouldn't we do the same? And what literature do we have?

AIM: 1970 UPC LT1, sheet A6 shows a note "production nut" for the carburetor fastener. There is no sheet A7 in any of the 1970 AIMs I have access to.
1971 UPC LT1, sheet A7 shows Nut part #396748 with a note that it was changed on 7-20-70 from 120368.
1972 UPC LT1, sheet A7 shows the carburetor mounting nut is now 120368.
I was curious and looked up LT1 in the 1969 AIM. It has a note by the nut (installs the same as L88). Both L88 & L71 show 120368 nuts for Holley mounting.

Kind of interesting, eh? OH, NO WASHERS on any of these pages. And some interesting options for insulators in 1972. There is much collateral information to be gained from the AIM(s).

"1970-75 Chevrolet by the Numbers" by Alan Colvin: He has blueprints of both the 1970 and 1971/72 LT1 intake manifolds, but these over-all views do not give a dimension for the height of the studs. Too bad. I had hopes. He does say in the caption for the 1971/72 manifold that the studs are silver. I take it he means silver colored – as opposed to the mineral.

There are more places to look in "the literature," but that is your homework assignment. Even if you don't have the actual literature (and you all should have at least the appropriate AIM), you might suggest places for others who do have the literature to look.

Then we turn to original cars: Dave posted pictures of his 1971 above. Here is my 1970.

I was able to get a measurement from the front driver’s side stud, and I made it at 1 3/8-inch above the carburetor mounting surface. Could the 1970 stud height be different from the 1971/72? Sure could, but I don’t know that it is – that is your job to find out.

I kind of think my nuts are natural (I know I should re-word that, but it si too late at night for that), but that opinion doesn’t do anything for your 1971 question. Best guess on the studs is zinc, but they would have been painted silver with the rest of the manifold after engine assembly.

Are we having fun yet?

[Robert S.]

Re: 71 LT-1 carb stud

Terry, thank you for taking the time to take some measurements and posting the photos. Your comments have been very helpful.

Bob

[Edward C.]

Re: 71 LT-1 carb stud

Guess I will leave my washers on for now on my 71.Thanks guys. Ed