Hi guys, i have a 383 that has been built pretty well for power. Right now its putting out 365HP and 427TQ to the wheels. At first I ran the engine on nothing less than 93 octane. Then as my wallet got thinner, i started using 89 and performance stayed the same and the engine never pinged or dieseled. I took a risk and added 87 to the 89 just to see what would happen. I decided i would add 87 to the tank until it started pinging or dieseling (if ever) and would add 93 to the tank to even it out if it did. Well now the tank has pure 87 in it, and ive been running it with 87 for a month now. Engine performance is the same and it dosent ping or diesel. Timing is set at 30 total centrifugal all in at 1600 rpm and 20 degrees of vacuum advance. This setup has been great for me!

Anyway, even if i have a straight pipe on this engine, it just isnt very loud. Today an LT1 w/ trick flow heads and a bigger cam fired up, and even with pipes all the way back, it was loud! And it wasnt annoyingly loud, it sounded great! I want that sound and realize that I need a bigger cam, but I dont want to go too big on the cam so I dont lose all the mpg i gained by using a t56. Basically my cruising speed is 1600 to 1800 rpm doing 70-80 mph. I dont want the cam to have to much overlap and have all my fuel going through the exhaust because the cruising speed is lower than usual carbed v8's.

Right now i have a comp cam 510/520 lift w/ 230/236 duration 112 LSA. What would you guys recommend for a nice cam that has a nice THUMP to it, that would also give me some more power on the top end? The engine has a holley double pumper 750 on it and its in an 87 trans am (about 3250LBS) with a T56 6 speed manual and a 3.42 torsen rear end. What do you guys recommend?

MPG wise, i get anywhere from 22-25 on the interstate. When I calculate it at most fill ups, I usually see 23mpg though.

 

What heads?
If your heads would handle it I would be running lots more lift with same duration .550 +

What exh do you have at present?

Hard to get both power and economy with same cam.

GMPP 847 cam ( 234 / 242 ) in my carbed 383. 410rwhp
Serious idle , great sound but I'm not concerned with economy

 

PBM heads, 2.02/1.60 valves aluminum

I have 3" single exhaust, no cat, edelbrock true flow muffler w/ 3" inlet and dual 2 1/2 outlets