by cammerjeff » Sun Jun 12, 2011 8:02 am
I never said that a good after market duel plane intake would not improve performance, it will, but without adding a good flowing exhaust system ( with or without headers ) a cam, and with almost all 70's cars changing the rear axle ratio to something more performance minded (most cars from the mid 70's have very high ratio's my 78 Sunbird wagon had 2.56's and the change to 3.73's alone made the car much more fun to drive!!!!!) If you car still has the stock ring and pinion in it, and it is 2.56-2.92 rang I would seriously consider that change 1st. A change to a 3.42 or 3.73 ring and pinion is a good 1st step.
Just my 2 cents worth.
As a kid starting to drive in the late 70's, I had a very nice 76 Grand Prix, 350 Pontiac 2 bbl, TH-400, and a Posi 2.42 rear axle stock, I changed out the intake and Carb 1st, as that is what I was told would really wake up the car!!!!! I got a stock Pontiac 400 intake and Q-jet off a 75 T/A, I didn't replace the Fuel pump with a 4bbl pump, The car went from running 18.30 to 18.38 after all the work. I installed a 4 bbl pump, and now ran 18.33. Got the Q-jet redone for the smaller engine, and fixed the problem with the secondary air flaps opening to soon, that got rid of the BOGG in the secondaries, and the rich mixture, now I was running 17.88!!!! At least it was finally faster!!!!! Duel exhaust got me sounding great, and running around 17.5, a cam change got me into the high 15's, I then finally swappped out the rear axle for one with a 3.23 posi, suddenly the car really woke up!!!!! I was now running 14.20's, and the low and mid range of the engine felt like I put a new motor in the car!!!! For the time my 4000lb luxo boat was still dirt slow, but at least it would not get beat by a V-6 Camaro any more!!!!
That is when I learned to start from the back 1st, I think I could have seen the 1 second or so performance pick up with just the axle change. I spent alot of time and $$$$ playing with the intake and carb, and I did learn alot, the secret is to not get fustraited and always treat it like a learning experiance.
Jeff R
1971 Catalina Freeway Enforcer
77 Astre Formula, some day soon powered by a 215 Buick V-8
1973 4-speed Lemans Safari STOCK!!!!! 1978 Catalina Safari
2006 Mallet Solstice, 6.0 LS2, 6-speed manual
2009 Solstice Coupe, 2.4, 5-speed Manual