1971 carb idle mixture limiters--original color

[Mike E.]

The plastic caps that prevented you from adjusting idle--what color were they from the factory?
GM dealers were instructed to Red plastic limiters to indicate that the dealer had altered the factory pre-set adjustment.

[Mike E.]

Re: 1971 carb idle mixture limiters--original color

I received an email from a reliable member who indicated they were black. Anyone that would speak to the contrary?

[Patrick H.]

Re: 1971 carb idle mixture limiters--original color

The new JG, which I suspect you have, shows them as red.

I thought that Jack Humphrey might have once posted photos of original caps.

[Russ S.]

Re: 1971 carb idle mixture limiters--original color

I don't recall ever seeing black ones. I have NOS red ones but they would be over the counter parts.

[Kevin G.]

Re: 1971 carb idle mixture limiters--original color

Reverend Mike, Are these the caps you're asking about?

[Mike E.]

Re: 1971 carb idle mixture limiters--original color

Kevin,
Those are the ones. Patrick, you are right--you and I both have been part of the JG team that produced the new 70-72 manual that indicates they should be Red. I was looking through some of my stacks of old Chevrolet-produced paperwork, and read that Chevrolet Dealership ServicevInformation Bulletin 71-T-4 dated February 12, 1971 indicates that the red caps would be dealer-installed to indicate that "the factory pre-set adjustment has been altered". In fact, that bulletin is reprinted in the back of the new 70-72 JG. So, as one who purchased a 71 Chevelle new (2-barrel) and remembered those caps but didn't remember what color, I thought I'd throw it out to the forum. I've seen red NOS caps for sale, and Chevrolet and responses to this thread are indicating to me that it's possible we could have an inaccuracy in the JG. Even if that color call-out is inaccurate, that new JG is a remarkable step forward, and Gary B should continue to be commended for its thoroughness and quality.
Mike

[Edward J.]

Re: 1971 carb idle mixture limiters--original color

I received an email from a reliable member who indicated they were black. Anyone that would speak to the contrary?

Mike I was a GM tech in the 70's and 80's and always remembered black cap's and the metal plugs later years on the mixture screws, removed many through the years.

[Jack H.]

Re: 1971 carb idle mixture limiters--original color

Red is the only color that's mentioned in GM literature ('71 Chassis Service Manual and Chevrolet Service News). Plus, there is a PN called out for replacement limiter caps (7043684) and I have some of those critters. They're definitely rust/red in color. But, that doesn't mean what was originally installed at the factory weren't a different color.

I chatted with others when making this input to the latest judging guide. There WAS a comment that a used black plastic limiter (QJet style) was found in a tool box and there was some debate as to making the current description read red or black. There were also comments to the effect that we see very few original cars wearing these... But, finally there was a report of a Bowtie car appearing in Boston wearing a set of red caps!

Still, those could have been replaced by service/early owners... And I did have a chat with John Hinckley who confirmed his recollection that the limiter caps WERE used on factory original cars. However, John didn't correct the colored picture of an NOS pack of red 7043684 caps that I squirted to him.

So, the current JG book says they're red. If someone can come forward with proof of the color being black for factory originals vs. red for service replacements (not hearsay--a GM drawing, Etc.), hey that's GREAT!

In the meantime, what to put on your car? Well, that's your decision. What you got from service as PN 7043664, when you can find them, WAS a rust/red color. But, hey--that rattle can of black plastic spray paint is darn cheap, eh?

[Gary B.]

Re: 1971 carb idle mixture limiters--original color

I have a set of black ones, broken into several pieces, from a Quadrajet in my tool box. I remember the car they came off of a few years ago. It was a 77, and has since gone down the road. They are the only set I remember the color of, but can remember removing lots of them in my younger years. Should have paid more attention back then. I can also remember removing the Holley plugs, but don't remember the color. The picture in the manual of the holley is from Al Wagners 300-mile ZR1. I saw that car before Al bought it, and they were on it then. I am pretty sure they are original.

I looked at a 400-mile 72 with a Quadrajet, a few months ago. They were gone. Which makes me wonder, did all the cars leave St. Louis with them on? Or did the dealers promptly remove them?

But, I'll keep looking. Maybe I'll see another set someday, if I live long enough.

Gary B

[Joe L.]

Re: 1971 carb idle mixture limiters--original color

All------


As I recall, there was a lot of trouble at the time making the cars run properly within the range of the factory-installed limiter caps. So, the caps were removed and a "full range of adjustment" thus obtained. The thing I don't understand is why anyone would have replaced the caps. The only time they might have been important is if a car had to undergo a smog inspection but that was not being done at that time, even in California.

[Patrick H.]

Re: 1971 carb idle mixture limiters--original color

I looked at a 400-mile 72 with a Quadrajet, a few months ago. They were gone. Which makes me wonder, did all the cars leave St. Louis with them on? Or did the dealers promptly remove them?

But, I'll keep looking. Maybe I'll see another set someday, if I live long enough.

Gary B

Need more info on that 72.

Does the "new" green 72 have them? Just thinking...

[Joe L.]

Re: 1971 carb idle mixture limiters--original color

All------


By the way, Chevrolet emphatically stated in service information that a "satisfactory idle is obtainable within the range of the mixture screw limiters". They lied.

[Kevin G.]

Re: 1971 carb idle mixture limiters--original color

I'm not quite clear? The photo I posted above, is my 18k mile '71 LS 5. Is their originality being questioned? Isn't this proof enough, that black were installed by the factory? I certainly didn't touch, change or alter them under my ownership, and doubt any of the previous owners did.

[Edward J.]

Re: 1971 carb idle mixture limiters--original color

I'm not quite clear? The photo I posted above, is my 18k mile '71 LS 5. Is their originality being questioned? Isn't this proof enough, that black were installed by the factory? I certainly didn't touch, change or alter them under my ownership, and doubt any of the previous owners did.

Kevin, they were black from the factory unless someone posts a red cap installed on a untouched car, I said prev. that all I remember were black caps, Red may have been serv. replacements but I cannot say as I never re-installed red ones or any after adjustments, in my dealership years.

[Mike E.]

Re: 1971 carb idle mixture limiters--original color

It is interesting to me that Chevrolet would, in a service bulletin (71-T-4) make a point of indicating there was a color change (red) for service caps, and that was to indicate adjustments had been made. In light of that, I would presume the following:
1) many dealerships chose not to order or install the red caps. It would be rather easy to recognize that if the original caps were broken off and gone, that an adjustment had been made. Plus, they cost dealership time to order them, pull them from the shelf, and install them, all for no apparent benefit to the customer or, more important, to the dealer.
2) over the counter caps are red
3) anyone trying to make their car "more correct" for bowtie judging, and feeling they need caps, would only have red available to them.
4) Chevrolet needed to make them available in order to remain in compliance with some clause in some sub-paragraph in some federal mandate regarding air quality.
5) whatever federal mandate it was, most dealers (service managers and techs) weren't concerned with it filtering down to them for compliance.