71 LT-1 Holley Question. Was the judge wrong?

[Mark A.]

I just had my 71 LT-1 judged at a chapter meet. In the mechanical section of the test, the judge said the tube attached to the choke pulloff on the right side of the carb, should be straight, and not have a bend in it as mine does. As my judging manual does not address this question, I would like to know if this is correct.
I also had points deducted for having nuts with washers holding down the carb. The judge stated that the washers should be integral with the nut. The manual on page 56, specifically states that Holley carbs in 71 and 72 use nuts with flat washers under them. I also had points deducted for using the round black clip for the choke rod which the manual states on page 58, is supposed to be used on 71 and 72 carbs. The longer one which the judge said I was supposed to have, is for 1970 only, according to the manual. The final deduct in question is, the judge told me my carb was to have the thin paper gasket between carb base and manifold. I have the 1/4" thick insulator between the carb and manifold as per the manual on page 56. I would like one of you judges out there or someone familiar with the LT-1's to shed some light on this for me. Thanks, Mark

[Terry M.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

How is this picture of my 1970. Please ignore the red residue from the un-leaded race gas. This is however a 1970, but I doubt a 1971 has a different choke pull off.

9B1 choke pull off(1).jpg

I thought all three years had the same attaching nuts for the Holley. I think the manual may be wrong here, but let's see what some other folks say.

You should have a thick gasket under the carb, but I think the manual calls for 1/4-inch IIRC. Did you show the judge the manual?

The process is:
First consider what you want to "fight" over. Pick your battles carefully.
1) discuss the "issue" with the judge. If you don't get no satisfaction (or Mick Jagger isn't around)
2) question the team leader (if there is one)
3) address the issue with the meet judging chairman.

Your last resort is to post here. BTW: How did you car do overall?

[Mark A.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

How is this picture of my 1970. Please ignore the red residue from the un-leaded race gas. This is however a 1970, but I doubt a 1971 has a different choke pull off.

[ATTACH=CONFIG]41585[/ATTACH]

I thought all three years had the same attaching nuts for the Holley. I think the manual may be wrong here, but let's see what some other folks say.

You should have a thick gasket under the carb, but I think the manual calls for 1/4-inch IIRC. Did you show the judge the manual?

The process is:
First consider what you want to "fight" over. Pick your battles carefully.
1) discuss the "issue" with the judge. If you don't get no satisfaction (or Mick Jagger isn't around)
2) question the team leader (if there is one)
3) address the issue with the meet judging chairman.

Your last resort is to post here. BTW: How did you car do overall?

Terry,
That is how my pulloff looks. It has the same bend. I have not gotten the results yet from the meet, as we left as soon as judging was over because of a 5 hour ride home. I did not show the judge my manual which I had sitting behind the car. I figured he should know, but I was meticulous when I built the car, and went by the book. When I got home, I decided to check on some of these things, and that is when I found that his findings did not line up with the manual. Mark

[Gary B.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

The rest of the story.
The Judging manual was brought out and was looked at. It was dated 1999. Not close to the current issue.
I said the nuts holding the carb down was a flanged nut, not a nut with a integral washer.
My experience is that 1971 LT-1's choke pull offs have a straight choke pull off tube. I think this was a change with the TCS Solenoid mounted on the front of the carb and the routing of the vacuum hoses. Maybe someone else will post a 71 LT-1 carb that shows this??
I also made a comment about the choke pull off rod and clip, saying I expected the 70 style clip on it, not the 72 style clip. I did not deduct any points, just made a comment to look into it.
My experience on the low mileage LT-1's, they did not use a 1/4" thick insulator under them, and a thin gasket on top of it, like yours. I would expect to see a thin gasket under the carb, not the thick 1/4" under it. On a Quadra-Jet, I would expect that thick gasket, but not on a Holley.
Gary

[Mark A.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

Gary,
The manual states: For 1971 and 1972 Rochester and for all Holley equipped Corvettes it is 1/4" thick.: That is why I installed the 1/4" thick insulator. Mark

[Mark A.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

Maybe someone knows the answer to this question as well. Neither of my manuals say anything about what head mark to use on the LT-1 intake manifolds. Paragon lists 2 types, both for the small block. One is the TR head, and the other is the M headmark. Both are listed for 71-82. Is there a right or wrong, or is this one of those cases where it depended on what bolts were in the tray on the line that day? Mark

[Terry M.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

Maybe someone knows the answer to this question as well. Neither of my manuals say anything about what head mark to use on the LT-1 intake manifolds. Paragon lists 2 types, both for the small block. One is the TR head, and the other is the M headmark. Both are listed for 71-82. Is there a right or wrong, or is this one of those cases where it depended on what bolts were in the tray on the line that day? Mark

Mark the headmark of any (well almost) fastener depends on what was in the bin at any particular time. The headmarks are indicators of the manufacturer, and it was common for Chevrolet/GM to source the fasteners from whichever manufacturer produced the lowest bid. They also sourced fasteners from multiple manufacturers so that if there was a delivery problem with one supplier they would have an alternate source. That is why manuals at best will give many headmarks that were common during that time period, but usually silent on the issue. The judges relay on their knowledge from looking at many original cars to decide if the headmark is typical or not.

Once many moons ago, when we were on the black background board someone was insistent about the headmarks for 1970 LT1s. I went and looked at mine and there were 7 different fasteners, if you count the TCS stud as one. The one for the lifting bracket has a built in washer, and as I recall is the only one that has that feature. When I judge, a dead give away for a "restored" (note I didn't say restoration) engine is that ALL intake manifold bolts are the same headmark. This tells me someone bought a kit from supplier x, y or z. I do not, however, deduct for that. There isn't enough points in the world to deduct for such things. That does however tell me a lot about what the restoration process has been. If you have any of the original bolts -- use them.

[Terry M.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

Gary,
The manual states: For 1971 and 1972 Rochester and for all Holley equipped Corvettes it is 1/4" thick.: That is why I installed the 1/4" thick insulator. Mark

Restoring a car by the manual, even the current manual, is not the way to receive no deductions. A judge can and will judge outside the manual. Then there are the places where the manual is wrong; that is why we revise the manual from time to time. Gary has extensive experience with low mileage Holley equipped Corvettes, and I respect his opinions. His statement about the choke pull off change due to the location of the TCS (or CEC) for 1971 makes sense. It will be interesting to see what others have with respect to that and the gasket, as there are some 1971 and 1972 LT1 owners on this board. It may be another place where we need to update the manual.

I know there is a drawing for the choke pull off clip in the current manual, and I believe it was in the Third (1999) Edition as well. I just gave my copy of the Third Edition to the NCRS archives while we were at Carlisle, not that I would have been motivated to dig it out if I still had it.

Mark did your car not give you some clues about how to restore it, or was it so Bubbaized that there was nothing left? Usually cars will give some clues as to how they were originally built. If the choke pull off change is true, I would expect a competent carburetor restoration shop to know about it.

[Joe L.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

The rest of the story.
The Judging manual was brought out and was looked at. It was dated 1999. Not close to the current issue.
I said the nuts holding the carb down was a flanged nut, not a nut with a integral washer.
My experience is that 1971 LT-1's choke pull offs have a straight choke pull off tube. I think this was a change with the TCS Solenoid mounted on the front of the carb and the routing of the vacuum hoses. Maybe someone else will post a 71 LT-1 carb that shows this??
I also made a comment about the choke pull off rod and clip, saying I expected the 70 style clip on it, not the 72 style clip. I did not deduct any points, just made a comment to look into it.
My experience on the low mileage LT-1's, they did not use a 1/4" thick insulator under them, and a thin gasket on top of it, like yours. I would expect to see a thin gasket under the carb, not the thick 1/4" under it. On a Quadra-Jet, I would expect that thick gasket, but not on a Holley.
Gary

Gary-----


GM says that an insulator of GM #3989390 was used as the carburetor base gasket for 1971 LT-1's. I can't say, for sure, if this insulator was actually used but I can say, for certain, that the 3989390 was a gray, open plenum type, square bore configuration and was about 1/4" thick.

As far as the choke pull-offs go, I always thought that 1970-71 Holley carbs used the curved nipple type and 1972 used the straight nipple type. I suppose it's possible that later 1971's might have used the 1972 style.

[Mark A.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

Gary-----


GM says that an insulator of GM #3989390 was used as the carburetor base gasket for 1971 LT-1's. I can't say, for sure, if this insulator was actually used but I can say, for certain, that the 3989390 was a gray, open plenum type, square bore configuration and was about 1/4" thick.

As far as the choke pull-offs go, I always thought that 1970-71 Holley carbs used the curved nipple type and 1972 used the straight nipple type. I suppose it's possible that later 1971's might have used the 1972 style.

Yes it appears that there are alot of gray areas on restored vettes. As Terry advises, I always prefer to use original pieces when I restore a C-3. On this particular car, it was quite original. However the manifold bolts, were long gone, so I went with Paragons advise. I purchased the correct used carb, ( the original was from a 72), then had it restored through one of the major corvettes suppliers who we all use for parts. I think they got it right. It's always great to talk to people on this forum, as there is a wealth of knowledge here. Thanks for all the great input to all. Mark

[Mark A.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

Terry,
The car Top Flighted. Mark

[Terry M.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

Terry,
The car Top Flighted. Mark

Congratulations

[Paul O.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

My old early Sept. build 1971 LT-1 #1914 had a choke pull off had a straight tube the gasket was 1/4" thick gray to green colored gasket have seen this type gasket till around S/N 6800. But Gary has seen many more 71 LT-1 then myself. The choke clip was 1970 style the bolts were as Terry stated several various manufactures. The hold down nuts were as Gary stated with a built in integral washer. Sorry no photos did my restoration before computer were in vogue.

[Dave S.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

71 LT-1 carb Photos 004.jpg71 LT-1 carb Photos 003.jpg71 LT-1 carb Photos 002.jpg71 LT-1 carb Photos 001.jpgHere are 4 photos from 71 VIN # 16798 (May build). They aren't perfect but tell a lot in response to the questions at hand. I'm the second owner and it is a 20k original mile car with both a 5 star Bowtie and Duntov awards. Can't say for sure everything is 100% original but the chances are very good. You guys can draw your own conclusions.

[Chris E.]

Re: 71 LT-1 Holley Question. Was the judge wrong?

Mark,

Since it sounds like the parts/mechanical/configuration question has already been answered by a couple guys, I'll address the judging question. It has been my experience with taking my car to 5 events (2 chapter and 3 regional) for Flight Judging that the way to get Top Flight is to follow the book. The way to get a HIGH Top Flight (97% or better) is to participate in more than one Flight attempt with your car and get a lot of eyes on the car. At the end of the day, these cars are pretty complex with many details on them. Getting it as close to perfect as possible (97% or better) requires more than one event. The only exception to that might be if you have already gone through the process with a previous car in that same judging class/model year.

Just my $0.03 (yup, used to be $0.02, but inflation got me)