Boss gas cap

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Graham Man

Well-known member
Joined
Nov 18, 2011
Messages
89
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Location
Midwest
My Car
1972 351Q Mach
1971 302 Fastback
Thought the Boss was a 1971 car, so it should have the aircraft style cap?
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But most have the 1972 Mach style... what is correct? or both?

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Plus I believe the flip-style cap was supposed to be replaced during a recall, due to the potential for easily spilling gas in a crash. My '71 Mach 1 429 still has one.
 
Thought the Boss was a 1971 car, so it should have the aircraft style cap?
View attachment 87704

But most have the 1972 Mach style... what is correct? or both?

View attachment 87705
The twist-on fuel cap is correct for a '71 Boss 351. The pop-open fuel cap was exclusive to and only production installed in '71 and early '72 on Mach 1s. There was no stand-alone option for the pop-open fuel cap, and it was not included in any option package.

Ford was taking a lot of heat from the Government over the pop-open cap design. During some accidents and rollovers, the cap was not sealing as well as the twist on caps and, in some instances, was popping open and spilling fuel. Ford revised the '71 pop-open cap four times and did not resolve the leaking problem. Since several new emissions and safety-related laws were going into effect in January '72, Ford dropped the pop open cap and phased the twist-on cap into production for the Mach 1s. The revised '72 sales brochures and order guides (as of 1/72) show the twist-on style cap on Mach 1s. The date the first '72 Mach 1 went down the line with the twist-on cap would be impossible to determine.

If you are looking for an original '71 twist-on cap, the Ford part# is D1ZZ-9030-A (ID# D1ZA-AA, AB, AC) and would have Autolite on the reverse side. Since Ford was transitioning to the Motorcraft brand from late '71 into '72, some early '72 caps could have the Autolite brand but have the '72 ID number. Those caps were D2ZZ-9030-A (ID# D2ZA-AA, AB) and replaced the D1ZZ-A cap. For a short time, a D3ZZ-9030-A (D3ZA-AA) fuel cap was used for the '73 Mustangs but was reverse-replaced by the reinstated D2ZZ-A. Of course, those would have Motorcraft branding.

NPD offers a repo cap that is cheaper than any NOS version of the twist-on caps and Concours correct. They have part # 9030-16, which does not include a security cable, and part # 9030-16A with the security cable.

https://www.npdlink.com/product/fuel-cap-vented/143676?backurl=search/products?search_terms=9030&top_parent=200001&year=1971&year=1971

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I've always thought that Ford should have used the flip-open cap on the Boss 351, as I think it appears to be racier than the twist -on, but that's not what happened. Oh well, I'd still take the Boss any day over my Mach.
 
I've always thought that Ford should have used the flip-open cap on the Boss 351, as I think it appears to be racier than the twist -on, but that's not what happened. Oh well, I'd still take the Boss any day over my Mach.
Similar to your point, I wondered why Ford dropped the Mach 1 style dual exhaust on the Boss 351.
 
Similar to your point, I wondered why Ford dropped the Mach 1 style dual exhaust on the Boss 351.
Ford did a lot of weird things back then it seems, Logic was NOT an option!!
Here's another one that doesn't make sense to me. Why didn't Ford drop in the stronger close ratio gear box in the Boss. They had it in the 429.
And the list goes on................
 
The chrome exhaust tips were exclusive to the '71-72 Mach1 (body code 05) with 4-bl engines ONLY. Even premium performance models, like the Boss 351 or the C and J 429s, didn't receive chrome tips unless the 429s were Mach 1s.
The Boss was a purpose-built performance car. Anyone familiar with the "Total Performance" days at Ford knew the curtain was drawing closed on the performance cars from all brands. The Boss was a "Last Call" and was based on the base 02 SportsRoof and was priced with no options at $4124.00 (as of 4/71). That is $1151.00 over the standard 02 price of $2973.00. For the difference of $1151.00, you got a vehicle with a unique powertrain that was not available in any other Ford-produced vehicle and was capable of holding its own at any traffic light "Manhood Test."
While nice, things like the urethane front bumper, chrome exhaust tips, and pop-open fuel caps would have inflated the base price of an already expensive car (in '71 dollars) and would not have improved the car's performance. Performance was what this "Last Call" Mustang was all about! A couple of my friends who owned Boss 351s were always working on removing things to make them lighter and faster.

While there were several options available through the sales department when ordering a Boss, the above-mentioned items, along with a few other restricted items, were not. But if you knew of a well-stocked Ford parts department (Ahem), they could put a smile on your face and make your Mustang happy. The Boss front spoiler, Mach 1 chrome exhaust tips, rear valance with the exhaust cutouts, and the pop-open fuel cap were just a few of the over-the-counter hot sellers we kept.
 
The prior owner of our 73 Mach 1 installed an oem (off a wrecked car) 71Mach 1 flip-lid cap on ours. It looks and works great. Seems to me I heard to install a 71 flip-lid was a PITA. Perhaps for the non-oem units out there. In any event, I HATE the twist off cap on our 73 Convertible, even though it is a nice looking cap. The reason? It only fits one way, and is too easy to forget to screw back on once done filling.

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My 71 M1 came with a flip cap. I added aftermarket flip caps to both of our 73 M1s. And I have two on the shelf.

I also added a flip cap to my 65.

They are all just bolt-on.
 
I FINALLY found an NOS Autolite gas cap for my Boss. Almost as hard to find as the D1ZF-ZA Autolite carb. A few months ago I'm at one of the few non-ethanol pumps in town and it wasn't taking my credit card. I went inside for help and when I returned the NOS Autolite gas cap I left on top of the pump was gone!!

Mine did not have a cable retainer.
 

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