year change modifications. I have a 1972 mustang mach 1, 351 "Q" code.

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jtassin

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1972 ford mustang Mach 1
 It was built in November 1971 as per Marti report.  When did the actual new changes as per 1972 models begin.  I have noticed some things that apparently are  carry over from 1971.   Such as the changes in horsepower ratings?

 

Hemikiller

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Model year changeover occurred in July 1971. a November car should be fully 1972 spec unless there were some mid-year changes.

HP ratings and engine specs would occur from Job 1 in order to be EPA compliant. 

 

Don C

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There's no clear cut answer as to when brake horsepower (gross) changed to SAE net horsepower ratings. California required all cars beginning with the 1972 model to use SAE net. Car manufactures complied for cars sold in California and during the 1972 model year all switched over to SAE net, not all necessarily at the same time. It behooved them to make the change as soon as possible due to the new EPA requirements, that way they could blame most of the apparent horsepower reduction on the new rating system and not so much on the actual power reduction of the engines. Hopefully someone has more knowledge as to when Ford made the change, and if all car lines and/or engines were changed at the same time.

 
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There were very few cosmetic changes. The majority of the changes involved safety and emissions related items, most of which would become effective on 1/1/72. A couple of safety-related items was the passenger side mounted seat belt light that actually went into production on 12/1/71 on the Mustang line. The Mach1 pop open fuel cap, which was prone to leakage from rear-end collisions or rollovers, was replaced with the twist on the standard fuel cap, although some early production '72s still had the pop open cap.

There was also a difference in how horsepower was now measured. The previous method was Brake horsepower which was measured at the flywheel with no water pump, alternator, PS pump, etc. The new SAE measured power at the flywheel with all the normal power-robbing accessories in place.     

For 1972, Ford had cut compression drastically and cam timing retarded 4 degrees on the majority of all gas engines in the entire car a light truck line. With the looming gas crisis/oil embargo on the horizon, Ford knew that the ability for all these engines to be able to run on the cheaper regular fuel would be a great selling point.   

 
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1971 Mustang Mach 1, M code, 4 speed.
The Mach1 pop open fuel cap, which was prone to leakage from rear-end collisions or rollovers, was replaced with the twist on the standard fuel cap, although some early production '72s still had the pop open cap.
While I can't prove it now as I have no pics of the door data stickers, both my 72 Mach's were dated 4/72. Why I remember that is because they were both made in the same month and I had both these cars at the same time. The red one was a Q code (that I should never have sold) and the pewter one was an H code. Both had pop-open gas caps. 

Oh! and if someone comments on the pewter one having 73 stripes, yes it did, I was given a set for free so why not.

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