1971 US Nationals class winners.

[DeuceCoupe]

Originally Posted by oldskool

"...1971 Lemans 2dr HT, 3575/325=11.00 455/325 auto-only 067 cam..."

I'll just throw this in here, for whatever it might be worth.

The '71 D-port 455 #66 heads are said to be really poor flowing. Not so the the '70, '72, & '73-'74 455 D-ports. There have quite a few of these other 455 D-port cars. But NOT the '71.

I think Ryan Schloe ran a '71 455 D-port Bird, for a little while. IIRC, he switched it over to a '73 455 D-port car. C.W, Hoefer still runs a '73, which has run a sec under, in the past.

I see that the '71 D-port got a 5hp decrease, for a Bird, in 2019. I figure Ryan & his Dad, John requested that reduction. It has worked for some guys, for certain combos, thru the years.

http://www.classracerinfo.com/Engine...9&MAKE=Pontiac

That is helpful about those #66 heads, nothing in Stan's database about those. Guessing they flow like the 1975-76 big chamber 6H heads, they Gonkulate 10-15hp lower than most D-ports.

It looks like those 1971 #66 heads were the 1st really big (114cc chamber) heads, so maybe they hadn't figured out how to make them flow yet, or maybe never did?

So I'd bet all the more on the 71 GTO convert 455/355HO combo, I bet it would outrun that 71 Lemans 455/325 combo by 4mph or so. That's IF the I/SA=11.00 car was really a 1971.

Those sheets tend to spell out Firebird-Camaro-Mustang when that is the car. But for a midsize eg Fairlane, they'll just say "Ford", although in one case it spells out "Chevelle". So maybe just Pontiac means Lemans/GTO. Maybe.