Need some help on a backfiring issue
03-30-2002, 01:26 PM
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Car: 1985 Trans Am
Engine: 350
Transmission: T5
Axle/Gears: 3.70
Need some help on a backfiring issue
The engine will start and idle at 1000 rpms just fine but as soon as I start to give it gas it starts to pop and backfire thru the carb. Seems that if I can get it from 1500-3000 without dying the engine will rev fine. But it really stumbles between that time.
Timing is set at 8 BTDC, I've double checked all vaccum leaks. I took the carb apart and cleaned it out good as well as checked the float levels. I've also replaced the cap and rotor.
The carb is an Edelbrock 750 electric choke. Engine is being run for the first time since head and cam swap.
Got any ideas? Is it possibly a choke issue?
Timing is set at 8 BTDC, I've double checked all vaccum leaks. I took the carb apart and cleaned it out good as well as checked the float levels. I've also replaced the cap and rotor.
The carb is an Edelbrock 750 electric choke. Engine is being run for the first time since head and cam swap.
Got any ideas? Is it possibly a choke issue?
03-30-2002, 02:19 PM
#2
BK,
NOW I know what you're been busy with!
Just a WAG would be lean mixture. The backfiring is common when lean, and the fact that you have no power until you reach higher RPM (when you're using the main ciruit instead of idle/transfer circuit of the Holley) could mean an idle air bleed or idle jetting issue. The fact that the idle is good and the main circuit is good may mean the transfer circuit has a problem. Once you get into the metering blocks on a Holley, you're on your own.
I'm admittedly not that much of a fan of Holleys, but I've got a spare. I'm certainly not your best resource on tuning them, so take it for what it's worth. The symptoms still make me think "lean mix".
One of these days I'm just gonna have to take the cruise up 43 to see what you're playing with...
EDIT: BTW - What happend to ICON?
NOW I know what you're been busy with!
Just a WAG would be lean mixture. The backfiring is common when lean, and the fact that you have no power until you reach higher RPM (when you're using the main ciruit instead of idle/transfer circuit of the Holley) could mean an idle air bleed or idle jetting issue. The fact that the idle is good and the main circuit is good may mean the transfer circuit has a problem. Once you get into the metering blocks on a Holley, you're on your own.
I'm admittedly not that much of a fan of Holleys, but I've got a spare. I'm certainly not your best resource on tuning them, so take it for what it's worth. The symptoms still make me think "lean mix".
One of these days I'm just gonna have to take the cruise up 43 to see what you're playing with...
EDIT: BTW - What happend to ICON?
03-30-2002, 02:39 PM
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Car: 1985 Trans Am
Engine: 350
Transmission: T5
Axle/Gears: 3.70
Hmmm so you're thinking lean? That may make sense since I went out there and tried playing with the choke keeping it wider open and it really stumbles. I think I'll step up the main jets a level and give it a try. Although the nice fireballs I've gotten lately would really turn heads on the street LOL
ICON is still alive and well. We're just not as active at stirring up crap as we used to be.
Everybody has there own little winter projects they're finishing up. Mine was just supossed to be a cosemetic undertaking but listening to those guys made me do more than I originally wanted to. 
Oh yeah any time you want to meet up that would be cool. Maybe we can hook up at GLD sometime if I can get my issues straightened out.
ICON is still alive and well. We're just not as active at stirring up crap as we used to be.
Everybody has there own little winter projects they're finishing up. Mine was just supossed to be a cosemetic undertaking but listening to those guys made me do more than I originally wanted to. Oh yeah any time you want to meet up that would be cool. Maybe we can hook up at GLD sometime if I can get my issues straightened out.
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