Re: '76 455 for fuel economy?
fwiw I have an 87 442 with a Cadillac 509, q-jet, 200-4r, and a working lock up converter. It had 3.42s ie a 2.29 final drive ratio and 28" tires. Mine was built with reliability driveability power brakes etc 1st performance 2nd and fuel mileage 3rd. This is not great its just what it is as I am not a tuner or a racer. Anyway I took her to the track when I first got it together, with me a full tank of fuel & a full size spare etc it weighed 3,840 on their scales. It ran a 12.50 at 110mph full exhaust street tires just as its driven. Two days later we took an out of state trip where I followed my buddys diesel truck & car trailer. He pretty much ran 75mph the whole way. She got 17.0 mpg. With a 230@50 duration cam which is obviosly not designed to maximise mileage but workes well with an honest 10-1 static and I believe was still in its zone at the 2,400/2,500ish rpms it was traveling at.
The way I see it is I am getting good performance (so far as their is definately more in it) with great driveability & reliability and decent mileage. I think if I had a th400 I would have gotten 12mpg and just as important to me turned a lot more rpms and been harder on the motor or had to give up acceleration to get back mileage & rpm. BTW its a zero deck motor and on the trip I ran 89 octane. It has a rebuilt stock lock up converter that stalls at 2,800 which as you know unlike with a 3 speed only comes into play at hard throttle.
My 200-4r is a basic street strip build with the only upgrade being the billet drum/shaft piece. I would recomend this part for any low 12 or faster 450+ cube big block gbody. Big blocks are more brutal and harder on parts than the equivelent turbo car. The Buick 455 in some ways is a lot like the big Cad in that it has high velocity heads that help to make considerable grunt low in the rpm range. In fact I think the Bu generally makes more grunt and lower than anything other than the big Cad. I have almost 9,000 hard as in riped up & wore out a new pair of large drag radials plus some used tires, miles on the transmission with no repairs. The only other upgrade being a large cheap transmission cooler. Its a great transmission if properly built & set up for a 4,000lb or less hot street car. I would not use it for a primarily dragstrip toy, something heavy like a truck or to tow anything.
Last edited by Vern; 07-16-2008 at 01:43 PM.
71 GS 455 Stage 1, Sold to be restored
87 GN, TE-60 turbo, Stretch intercooler, 42.5lb injectors, 3" downpipe, 3,000 stall lockup converter, Meth/water injection, Original owner
87 Olds 442, 509ci Cadillac, 800 Q-jet, Performer intake, Street ported heads, 230@50 518 lift cam, Headers, 200-4R, 2800 stall lock-up converter, Electric fans & intank fuel pump, AC, Factory oil pres & tach work, Functional Hurst hood, Rear spoiler, 36mm front swaybar, 17mpg hwy, Both 2run 11.8ish 113+ on pumpgas