gen2hemi
former ASE knuckle buster
- Joined
- Mar 15, 2010
- Messages
- 63
- Reaction score
- 1
That plug is way beyond a couple jet sizes rich. The power valve tipping in early combined with jetting maybe, but it even looks richer than that and so does your mileage. AFs in the 12s generally look black but not sooted
Moper is right, your power output on the dyno sheets are way down for that kind of setup. Overcarbed and overcammed would have shown signs of waking up 5500-6600.
Back to the OP your carb is not the MPG problem. Not on its own anyway. Your cam and its installed centerline and overlap are making the engine wheeze at cruise. Dynamic compression determined by valve timing at these part throttle power settings influences the engines economy. The initial timing, advance curve, and lack of vacuum advance is also an economy issue.
Get a vacuum gauge rigged and work your timing at idle and then monitor your cruise vacuum. Hope you can get it 15 or better or the cam is fighting you the whole way. After you have the timing worked out drop in the main jet change and power valve at .5 your new idle vacuum.
I have a real time AF on my carbed engines too. My dual quad hemi with shaker took over an hour for every jet or metering rod change (2xEdelbrock AVS) but after 6 or 7 rounds of hassling with changes and measurement, the payoff is it runs like an EFI setup.
Moper is right, your power output on the dyno sheets are way down for that kind of setup. Overcarbed and overcammed would have shown signs of waking up 5500-6600.
Back to the OP your carb is not the MPG problem. Not on its own anyway. Your cam and its installed centerline and overlap are making the engine wheeze at cruise. Dynamic compression determined by valve timing at these part throttle power settings influences the engines economy. The initial timing, advance curve, and lack of vacuum advance is also an economy issue.
Get a vacuum gauge rigged and work your timing at idle and then monitor your cruise vacuum. Hope you can get it 15 or better or the cam is fighting you the whole way. After you have the timing worked out drop in the main jet change and power valve at .5 your new idle vacuum.
I have a real time AF on my carbed engines too. My dual quad hemi with shaker took over an hour for every jet or metering rod change (2xEdelbrock AVS) but after 6 or 7 rounds of hassling with changes and measurement, the payoff is it runs like an EFI setup.