crunchyskippy

I was surfin' the Autzone.com website and came across their Tune-Up specifications. In it, I noticed a pretty big HP variance among years...namely the between 1971 302 producing 210 HP and the 1972 302 producing only 140 HP?!?

I always thought the 289 and 302's were basically unchanged for years with interchangeable parts. So I'm confused as to why they would decrease horsepower. Perhaps its was related to emissions control, fuel economy, or even insurance rates???

So my last question is this: Could the owners of a 1972 302 make simple modifications to produce the same HP of a 1971 302 (210 HP)?

In case I'm misreading something, here's the link:
http://www.autozone.com/images/cds/g...3d801c305e.gif
and
http://www.autozone.com/images/cds/g...3d801c305f.gif

Thanks.

Yonco

Iread somewhere ina mustang book that states its all in the way the HP was rated, They still had the same HP, butit was tested differently, so the #'s were lower so they would pass emissions/stuff -Jon

my77stang

ratings were alot of it, but emissions in the mid 70's killed the HP. not sure if they used different cams or lower compression pistons in those years or not.

Oxnard Montalvo

Prior to 1972 automaker horsepower ratings were gross ratings, measured at the flywheel, nothing that drew power away from the engine was present. No pumps, no mufflers, no alternator, no nothin'.

Beginning in 1972 net ratings were employed, again measured at the flywheel, but at this point all the accessories , exhaust and such were attached to the engine.

Here's the skinny.


http://en.wikipedia.org/wiki/Horsepower

P Zero

In the early 70's there was a push for fuel economy and cleaner cars. In 1973 (99% sure), is when ALL american cars had to have cats, and meet certain emissions requirements. So they did a combination of things to meet those things, smaller cams, smaller displacement, 2 barrells instead of 4, cast iron manifolds instead of tubular style stuff, smaller ports, etc.etc.. IM sure the big difference was because they were gearing towards that in 1972 and thats why it was 70 hp less. Maybe it was their guinea pig year?
My first car was a 1979 5.0L 4spd. It was rated at a whopping 149hp. That was thanks to the awesome 2barrel and single exhaust, cast iron manifolds and a 200 lift cam [:-].
-P.

Colorado_Mustang

The '72 302 had a smaller cam (almost .1" of lift was lost)and lowered compression (1.5 points or so). The 302 was really a dog between '72 and '83, when the HO came out.

The fix is real easy. Flat top pistons and a new cam.

crunchyskippy

All good information... Thanks everyone.