Madmax

Wondering if anyone can give me some baseline carb jetting to begin with on my combo. Carb is original Weber (AFB) carb with stock jets. Engine is base 330hp 454 with L-29 Vortec heads, Edelbrock Performer RPM intake, GM 454HO cam (.511/.540 lift, 211/230 duration on 112), Gil HP500 exhaust, and K&N 14x3 filter.

Original jetting is .098 on the secondary, .104 primary with a 47/75 rod. I changed the secondary side to .107, and the primary side to .110 with a 42/68 rod. Does this sound close to baseline from? I don't wanna run it 2 lean, but don't wanna have it way 2 rich also. Boat is Baja 232 turning a 25 mirage plus prop. Was turning 4600rpm (approx 68mph) Monday morning (approx mid 60's temperature-wise) and was breaking up like a severe lean condition with stock jetting. I'm not really interested in doing this again, since i'm sure this isn't 2 good on it. Thanks for all the help.!

David Stotz

What do the plugs look like? Maybe it's not a lean condition but an ignition problem.

MACDAD260

I am going through the same thing. I swapped the 330hp 454 for a 502 mag and am using the stock Weber carb also. With the original jetting, ( .107 pri, .098 sec, 6542 rod) I had a hesitation when going from cruise to full throttle. I didn't hear any popping. The next time out I went to a .110 pri, and used the .107s in the sec. I did not change the rods. That cured the hesitation. I have now gone up to a .116 pri and .113 sec. Still runs strong with no sign of being too rich. The largest jets they make are .119 so I can't go up much more. I think I am in the ballpark, though. Keep going up on the jetting untill you can tell it is not running as strong, then go back down 1 size. This way you will not hurt your motor. Better to be too rich than too lean. Keep us posted on your results. Good luck. Doug