71 gas cap question.

[Michael G.]

I have the second version of the 70-72 gold irridate gas cap (believed to be original) and have some evidence of a textured white coating on the underside of the cap. I'd like to know if this was from factory, or a previous owners attempt to cover the light rust that had started to form on the underside. If this is factory, please advise on what you have found to be a close copy for this thick, textured coating.Thanks, Mike

[Pete B.]

Re: 71 gas cap question.

I belive what your seeing is corrosion of the original plating. Water will condense to the top of the tank, or the cap.

[Joe L.]

Re: 71 gas cap question.

I belive what your seeing is corrosion of the original plating. Water will condense to the top of the tank, or the cap.

Pete and Michael-------


Yup!

[Edward J.]

Re: 71 gas cap question.

Mike, I think the judging manuel calls for the original cap to have a zinc or clear zinc finish, and wasn't 71 suppose to have a red decal on it ? some of the second design were gold irr. plated. but the the logo on the inside of the cap was a big letter S. as the originals had the smc logo, in small font.one other detail is 70/71 had scaloped edges on outside of cap.72 was smooth edges.

[Jack H.]

Re: 71 gas cap question.

It's the 'early' 1971 cars that had the red decal (CAUTION Open Slowly). Somewhere during the '71 model year, Stant changed their assy tooling to stamp the warning into the surface of the cap (cost reduction?).

Exactly when this happened, I don't think we really know. Plus, the early and late parts were probably binned together in inventory, so the early caps may have persisted in production for quite a while...

Currently, the '70-72 JG Book advises ALL caps were cad/zinc silver in color with the SMC emboss. The gold dichromate finish shows up as a judging criteria in the '73-74 JG Book, but even there the SMC vs. block-S emboss continues as an originality issue...

[Dave S.]

Re: 71 gas cap question.

It's the 'early' 1971 cars that had the red decal (CAUTION Open Slowly). Somewhere during the '71 model year, Stant changed their assy tooling to stamp the warning into the surface of the cap (cost reduction?).

Exactly when this happened, I don't think we really know. Plus, the early and late parts were probably binned together in inventory, so the early caps may have persisted in production for quite a while...

Currently, the '70-72 JG Book advises ALL caps were cad/zinc silver in color with the SMC emboss. The gold dichromate finish shows up as a judging criteria in the '73-74 JG Book, but even there the SMC vs. block-S emboss continues as an originality issue...

Jack,
#16798 and #21467 both have gas caps with the red decal. 99.9% sure they are original. Based on that and others I have seen I'd respectfully disagree with your "early" time frame.

[Steven G.]

Re: 71 gas cap question.

71' VIN. #1563 has red label, but this is early as previously mentioned. Steve

[Jack H.]

Re: 71 gas cap question.

You can respectfully disagree, but it's not MY early time frame reference... It's what's published in the '70-72 Judging Guide, amigo.

[Edward J.]

Re: 71 gas cap question.

Jack, could be that the JM is in need of alittle more research on the gas caps? With Daves serial numbers they are surely of the later, Daves cars are of a rare breed.

[Dave S.]

Re: 71 gas cap question.

You can respectfully disagree, but it's not MY early time frame reference... It's what's published in the '70-72 Judging Guide, amigo.

Jack,
Sorry to ruffle your feathers. Just trying to constructively contribute to the board and our fellow members. I will be sure to post this info on the Revision Team section that I/You both have access to. My name is Dave, not Amigo.

[Paul O.]

Re: 71 gas cap question.

Like Dave I have seen many late built original cars with the red tag on a 71 cap. I would give the benefit to the owner if he had ether style cap during judging for a mid to late production car. As with whats in the manual it is a Judging Guide there are still many item missing and not correct items. It is a living document.


Michael the white coating on the under side we believe is caused by the Tetra-ethyl lead in the gas of that time.

Paul 18046

[Jack H.]

Re: 71 gas cap question.

You are 100% correct! The book IS a GUIDE--that's why we changed the name of the publication about 10 years ago. It's intended as a supplement to each judge's personal knowledge.

I suspect this was a running change at Stant (cost reduction-eliminate the stick-on label) and if so, it would take access to BOTH Stant's drawing files as well as GM's purchasing records to find out when the change occurred.

Even then, we wouldn't know the quantity of 'early' caps that were on-hand at St. Louis when the change occurred or when the LAST of the 'early' caps left the plant. Plus, it's not unusual for 'funnies' to happen in the closing days of a model year production run when factory planners are trying to use up all of this year's parts to get ready for next year's car build. They hit the back of the shelf and bottom of the bin in terms of inventory use.

You'll note that there's no guidance in the JG on when the change occurred (effective VIN). I suspect that's because we simply do NOT know.

Plus, observations of a car here, a car there, are just that SMALL SAMPLE evidence. As the book is written, it's up to each owner and those judging to assess what constitutes 'early' vs. 'late'. That's a situation we face with almost every running change issue in Corvettedom...

[Joe L.]

Re: 71 gas cap question.

You are 100% correct! The book IS a GUIDE--that's why we changed the name of the publication about 10 years ago. It's intended as a supplement to each judge's personal knowledge.

I suspect this was a running change at Stant (cost reduction-eliminate the stick-on label) and if so, it would take access to BOTH Stant's drawing files as well as GM's purchasing records to find out when the change occurred.

Even then, we wouldn't know the quantity of 'early' caps that were on-hand at St. Louis when the change occurred or when the LAST of the 'early' caps left the plant. Plus, it's not unusual for 'funnies' to happen in the closing days of a model year production run when factory planners are trying to use up all of this year's parts to get ready for next year's car build. They hit the back of the shelf and bottom of the bin in terms of inventory use.

You'll note that there's no guidance in the JG on when the change occurred (effective VIN). I suspect that's because we simply do NOT know.

Plus, observations of a car here, a car there, are just that SMALL SAMPLE evidence. As the book is written, it's up to each owner and those judging to assess what constitutes 'early' vs. 'late'. That's a situation we face with almost every running change issue in Corvettedom...

Jack, et al------


Keep in mind that St. Louis did not rotate their stock. So, as probably cases of gas caps came into the plant, they would likely have been put into storage areas in which the newer stock was placed in front of any older stock remaining when the newer stock arrived. So, cases of the newer caps came in and went out to the assembly line while older stock languished in the rear of the storage area. At some point, some of these cases might have been drawn out and, then, with new stock arrival, the remaining older stock was covered up. It might have been towards the end of the model year when there was a concerted effort to draw down existing stocks to "zero" that the last cases of older stock finally got used.