[70 Dream]

Originally Posted by geeteeohguy

Finally, about 3 years ago, at 235,000 miles, I installed a set of 87cc #15 heads off of a '70 455. I reworked the heads (screw in studs, etc) and ended up with right on about 9 to 1 compression. I kept the 068 cam. Gas in CA is now 91 octane, and over $3.50 a gallon. The car ran like it dropped 1000 pounds of dead weight. It was fast, light on its feet, and a joy to drive. I next slipped in a 2.56 rear end (it was a posi and it was a freebee) and I lost a little accelleration off the line....but it was worth it. I've gotten over 20mpg with this set-up, and it will do it on 87-89 octane without pinging. It cruises like a dream, and the fact that it sips gas (for a GTO) allows me to drive it a lot without feeling depressed and broke. I applaud your choice of a 2.93 gear....It's a perfect ratio for a TH400 GTO. My long-winded point is, drop your compression to 9 to 1 or thereabouts, and enjoy the car. I have had a lot of stock Pontiacs over the years, and NONE of them ran without pinging on less than 94- plus octane fuel, which you can't get at the pump any more.

Thanks for your post, GTOGuy, I am going to stick with my plan and do what you did, and this includes trying to find 2.93s or similar.

Won't know the final cc on my heads until the machine work is done, I suppose. I am going to start a new thread on cam selection, maybe you an help me with my cam choice?