holley carb mystery - Ford Mustang Forum
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post #1 of 11 (permalink) Old 3 Weeks Ago Thread Starter
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holley carb mystery

I purchased a 73 mach 1 last year. 351 4v w/ 4 bolt mains, 4 speed. has a holley 4160 carb. ran the numbers by holley to see what is was, and got a surprise. they told me they supplied this carb to ford in 72 and 73, for use on 351 engines. 605 cfm. I have never heard of a holley being used from factory in 73, and my ford factory repair manual does not show it anywhere [ I have complete set of 1973 ford repair manuals, still in the box it was shipped in, with a postmark of march 74] does anyone have any info on this?

also, the only vin code it shows for 351 4v is Q, and the factory manual lists it as a CJ, which I believe is the only place ford refers to this engine as a cobra jet. the question arises in the cam and head spec charts. there is a CJ cam listed, and also an HO cam, which has more intake lift, and while the compression ratio is listed at 8:1 for both, the HO combustion chamber volume is listed as being smaller. I can't seem to find any other info anywhere on this HO listing. anyone have any clues? i'm wondering if such an engine exists, or if Ford changed their mind after manual was printed. the service spec supplement, printed July 73, does not mention any HO engine. i'm curious more than anything, I don't intend to tear the motor down at this time, just wondering how much weirdness I may or may not have.

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post #2 of 11 (permalink) Old 3 Weeks Ago
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The "Q" code for '73 was basically just the 4V designation for the 351C. It's a 'Cobra Jet' in name, at least. If I remember right, in '73, they downsized the valves a little bit for your engine, halfway through the year. It still has really big ports, which hurt low-RPM torque production, and "open" combustion chambers which makes your engine rather octane sensitive.

I think they dropped the name "Cobra Jet" in '72 and 73 officially, but the 4V "Q" code engine is still referred to as such in a lot of the documentation - just not in advertising. I am not an expert on Mustang engine marketing, so I could be wrong about this.


The "HO" version was the Boss 351, not the Cobrajet, I believe, and had an R code. I'm not even sure it was available in '73, so that may be part of the confusion about compression ratios, etc.


It's a real Cleveland though, not an "M" so you don't have the incredibly long heavy pistons and larger, heavier block.

Cool car! =)

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post #3 of 11 (permalink) Old 3 Weeks Ago Thread Starter
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yeah, low end sucks, but you get up to 3500 rpm and she really takes off. the 4 speed helps with that. you are correct about the advertising. back in my wasted youth I had a 71 cougar with what I thought was the HO engine, same as boss, but with 10.7:1 compression and hydraulic tappets instead of the boss solids. this engine runs good on 91 octane, so I know it's not one of those, I had to run 99 octane in the cougar. the big question is the carb, according to holley it's a numbers matching carb, but I can't verify that with any of my ford stuff. it's a beautiful car, even though it's got some repop stuff on it. I've got most of the bugs worked out to the point I can drive it reliably, and it's a lot of fun. from what I've found out so far, it was dragged out of "storage" after 26 years of sitting, back in 2014. body is very solid, drives like a dream. got a marti report and original factory invoice, trying to piece together it's history
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post #4 of 11 (permalink) Old 3 Weeks Ago
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As I've probably mentioned on this forum before, I had a '73 Gran Torino Sport, which I ordered from Ford. It had the 351C, dual exhaust, and a Ford 4 barrel carb. Great engine, but it suffered from the onset of emissions stuff. Cold starts were a problem, which I finally fixed by replacing the carb with a Holley and removing some of the additions.

A good friend who used to drag race told me the engine was worth as much as the rest of the car.

When my ex left we agreed she would get it; I kept the '66 Mustang, which I still have.
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The "HO" engine was '72 ONLY and was basically a low compression Boss 351. It used an open chamber head and flat top piston and smaller solid lifter cam. It was rated at 275 HP . In '73 the Q code hydraulic lifter ( small intake valve) engine was the top of the line.
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post #6 of 11 (permalink) Old 3 Weeks Ago Thread Starter
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so the editor just missed taking the 72 ho info out of the manual update-one mystery solved
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As you can tell, cars were not built/tracked they way they are today... and holley provided a lot of "Special/Limited" production carbs for Ford (etc.). many times it was never documented in production because it was a limited production "fix" for either a mechanical issue or even a supplier issue.... dealers were also authorized to make these types of switches as well....sometimes customers would require it because of a known issue and the dealer would make the part change with Fords blessing. Our 65 mustang has been in the family since new...was a special order.... and make a long story short, has a Holley carb that was on there since new (from Shelby's shop...and no it is a not a Shelby). that supposedly was not around until the early 70's... but matches the Ford intake perfectly!


Heck, if you look carefully at the "real" history of the Shelby Cobra's (1960's), Ford was providing the engines to Shelby to drop in them (with the tranny's from BW, which is all Shelby's shop really did), production of the 427 ran short and was routinely replaced with the 428.....


IMHO, you got a real good one!!!!!!!!!!!!!!!!!!!!!!!!!!
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Quote:
Originally Posted by 73 351Q View Post
so the editor just missed taking the 72 ho info out of the manual update-one mystery solved
Actually it is more common than you would think. In '68 , manuals listed a 427 for the Mustang ( which didn't happen) and nothing about the 428CJ which DID happen. Last minute decisions over ride printed matter done at an earlier date.

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post #9 of 11 (permalink) Old 3 Weeks Ago Thread Starter
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thanks for the input, that all makes sense. before I retired part of my job was proofreading and editing a motorcycle aftermarket parts catalog, invariably something major would happen the week after it went to the printer!!
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What is the "list" number on the Holley on your car?

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post #11 of 11 (permalink) Old 3 Weeks Ago Thread Starter
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can't find the notebook I wrote the numbers on, will have to go out to garage this weekend and uncover it to get them
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