Hi.
Recently bought a impco 425 for my 350 Chev fitted to a fourbarrel thottle body ( Straight Gas).
I have fitted it up and cant seen to stop it idelling rough and smelling very rich.
I have adjusted the richness screw all the in and out and it seem to make no difference.
It has plenty of power on a road test , but idels shit and stinks of rich gas.
Any ideas before i go to a pro!
Grant.
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Tuning 425 Impco Gas mixer?
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Tuning 425 Impco Gas mixer?
GU III TD42T UFI18G Cross Country IC, 20 PSI. Neeeeeed mooooore Fueeeeeel.
Re: Tuning 425 Impco Gas mixer?
Are you sure you're adjusting the right screw?
The idle adjustment is the screw (or recessed Allen key on later models) offset to the side of the carb, the power adjustment is the one in the centre.
The idle adjustment is the screw (or recessed Allen key on later models) offset to the side of the carb, the power adjustment is the one in the centre.
Last edited by 351ciofgrunt on Tue Aug 24, 2010 7:16 am, edited 1 time in total.
GQ Patrol Wagon, 6 point roll cage
351 cleveland, CHI heads, solid cam, Funnelweb single plane, 750 HP DP
351 cleveland, CHI heads, solid cam, Funnelweb single plane, 750 HP DP
Re: Tuning 425 Impco Gas mixer?
The idel lean and rich screw can be seen bottom left of mixer and the power screw is the large hex nut at the lower front that can not be seen.
This is what i have always belived !!!
Grant.
GU III TD42T UFI18G Cross Country IC, 20 PSI. Neeeeeed mooooore Fueeeeeel.
Re: Tuning 425 Impco Gas mixer?
Both adjustments are on the side of the carb that is opposite to the gas inlet, in your photo it is the side to the left. So your photo is no good because we can't see them.
The idle mixture is the lower right side, the power is in the centre
The idle mixture is the lower right side, the power is in the centre
Last edited by 351ciofgrunt on Tue Aug 24, 2010 7:16 am, edited 1 time in total.
GQ Patrol Wagon, 6 point roll cage
351 cleveland, CHI heads, solid cam, Funnelweb single plane, 750 HP DP
351 cleveland, CHI heads, solid cam, Funnelweb single plane, 750 HP DP
Re: Tuning 425 Impco Gas mixer?
This side?
Re: Tuning 425 Impco Gas mixer?
Yes thats the one!
So this photo is the later models that don't have srews, they have recessed 3/16 allen keys for the adjustments.
Do you see the two shiny circular bits with holes in the middle, thats them.
The one is the centre is the power adjustment. The one slightly lower and to the right is the idle adjustment.
Turning them out is rich and in is lean.
If you have the earlier model impco's then the idle adjustment is a screw and the power adjustment is a bolt
So this photo is the later models that don't have srews, they have recessed 3/16 allen keys for the adjustments.
Do you see the two shiny circular bits with holes in the middle, thats them.
The one is the centre is the power adjustment. The one slightly lower and to the right is the idle adjustment.
Turning them out is rich and in is lean.
If you have the earlier model impco's then the idle adjustment is a screw and the power adjustment is a bolt
GQ Patrol Wagon, 6 point roll cage
351 cleveland, CHI heads, solid cam, Funnelweb single plane, 750 HP DP
351 cleveland, CHI heads, solid cam, Funnelweb single plane, 750 HP DP
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