SBC lower rpm misfire, revs pretty clean above 2500rpm.
05-06-2014, 08:58 AM
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Car: 1984 Firebird (89 Formula Clone)
Engine: 357
Transmission: m29 T56
Axle/Gears: 3.27 9 bolt Borg Warner.
SBC lower rpm misfire, revs pretty clean above 2500rpm.
Alright my SBC is annoying me now, I let it sit for 1 week, didn't touch it. It used to start on a dime, Now its really hard to start and misfires and rumbles under 2000-2500 rpm. If i rev it up, it seems pretty clean. I did have a couple scorched boots but i replaced those. Cap and rotor is good, plugs have been swapped out, no vac leaks that i can see, valves are adjusted well, i have compression air fuel and spark... Any Ideas?
I did recently adjust the valves but this issue was consistent before that...
I did recently adjust the valves but this issue was consistent before that...
05-06-2014, 12:39 PM
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Car: 1984 Firebird (89 Formula Clone)
Engine: 357
Transmission: m29 T56
Axle/Gears: 3.27 9 bolt Borg Warner.
Re: SBC lower rpm misfire, revs pretty clean above 2500rpm.
I did find a little debris in the regulator when i disassembled it, Maybe i have some crap in my tank, going to take the carb apart later and inspect.
05-06-2014, 12:59 PM
#3
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Re: SBC lower rpm misfire, revs pretty clean above 2500rpm.
Carbed?
EFI?
Stock?
EFI?
Stock?
05-06-2014, 01:00 PM
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Car: 1984 Firebird (89 Formula Clone)
Engine: 357
Transmission: m29 T56
Axle/Gears: 3.27 9 bolt Borg Warner.
Re: SBC lower rpm misfire, revs pretty clean above 2500rpm.
Carbed, summit racing 750 vac secondary carb. Vac advanced MSD streetfire distributor. built 357 forged pistons, alum heads, etc.
05-12-2014, 11:53 AM
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Car: 1984 Firebird (89 Formula Clone)
Engine: 357
Transmission: m29 T56
Axle/Gears: 3.27 9 bolt Borg Warner.
Re: SBC lower rpm misfire, revs pretty clean above 2500rpm.
Update:
I have tried:
New coil
New Rotor
known good dist
New ignition module
New plugs
New wires
Known good carb
There aren't vac leaks as far as i can tell ( need to confirm with vac gauge yet )
Cleaned out fuel filter
I have a suspicion my fuel pump may be on its way out, need to confirm
I have tried:
New coil
New Rotor
known good dist
New ignition module
New plugs
New wires
Known good carb
There aren't vac leaks as far as i can tell ( need to confirm with vac gauge yet )
Cleaned out fuel filter
I have a suspicion my fuel pump may be on its way out, need to confirm
05-12-2014, 11:58 AM
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Re: SBC lower rpm misfire, revs pretty clean above 2500rpm.
what cam is in the engine? What is the timing?
05-12-2014, 12:09 PM
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Car: 1984 Firebird (89 Formula Clone)
Engine: 357
Transmission: m29 T56
Axle/Gears: 3.27 9 bolt Borg Warner.
Re: SBC lower rpm misfire, revs pretty clean above 2500rpm.
initial timing is about 24-25 degrees
I have a .488/.510 234/244 duration
Camshaft: Performer RPM
Part #: #7102
It literally ran so perfect before i parked it, came back out to this issue, I dont get it.
I have a .488/.510 234/244 duration
Camshaft: Performer RPM
Part #: #7102
It literally ran so perfect before i parked it, came back out to this issue, I dont get it.
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05-12-2014, 08:38 PM
#8
Senior Member
Re: SBC lower rpm misfire, revs pretty clean above 2500rpm.
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