Hey everyone. I have a Vortec headed 355 in my 86 olds cutlass. It have a howards roller 180325-08 camshaft and 10.25:1 compression, scorpion full roller rochers, edelbrock performer rpm intake and edelbrock thunder series 650cfm carb. Has an 2800-3200 stall converter rebuilt th350 by a very reputible racing trans builder in the area (for 450hp) and 3.73 gears with 25.5" tall tires.
Exhaust is hooker 1 1/2" primaries into 3" collectors which get squeezed down to 2" and then adapt into 2 1/4" flowmaster 40 series mufflers. (on the to do list for bigger exhaust)
I really expected this combination to pull harder but it feels like it pulls hard from 3500-4500 then just pulls flat and gives up around 5500-5800. I only have maybe at most 1" of vacuum at WOT which most people recommend upgrading to a bigger carb and other say a couple of inches is ok.
I have a wideband in the car and at WOT I am right around 12:1 in the top of 1 into 2 and into 3 gear. Last I checked I thought the timing was at 36* which I believe when we dynoed the engine it was at 34* (might have been moved during install) also running 93 octane since that is what it was dynoed on. Could retarding the degrees 2* back to 34* help pickup some top end? I had the plugs out yesterday and there were no signs of any issues like speckles from detonation besides a rich idle that I have fixed but the porcelin was a nice light tan.
Innovative recommends 12.5-13.5 at WOT which I will shoot for Wednesday when I take the car to the track. Can anyone suggest what may be wrong? I am assuming the exhaust and carb could go bigger.
Thanks for your input,
Shane
Exhaust is hooker 1 1/2" primaries into 3" collectors which get squeezed down to 2" and then adapt into 2 1/4" flowmaster 40 series mufflers. (on the to do list for bigger exhaust)
I really expected this combination to pull harder but it feels like it pulls hard from 3500-4500 then just pulls flat and gives up around 5500-5800. I only have maybe at most 1" of vacuum at WOT which most people recommend upgrading to a bigger carb and other say a couple of inches is ok.
I have a wideband in the car and at WOT I am right around 12:1 in the top of 1 into 2 and into 3 gear. Last I checked I thought the timing was at 36* which I believe when we dynoed the engine it was at 34* (might have been moved during install) also running 93 octane since that is what it was dynoed on. Could retarding the degrees 2* back to 34* help pickup some top end? I had the plugs out yesterday and there were no signs of any issues like speckles from detonation besides a rich idle that I have fixed but the porcelin was a nice light tan.
Innovative recommends 12.5-13.5 at WOT which I will shoot for Wednesday when I take the car to the track. Can anyone suggest what may be wrong? I am assuming the exhaust and carb could go bigger.
Thanks for your input,
Shane