Alcohol carb tuning

[mikedevore]

Still new at this alcohol fuel thing.
Took the Barracuda out Saturday, it ran like it should.
10.42 @ 127.8 MPH in 100 degree heat.
It seemed rich. It would blow white/gray smoke on launch & clear up 60ft out.
I was told it was too rich.
Spec as follows, Holley 950HP out of the box with the exception of dropping the jets from 144 to 142's.
Where do you start, smaller jets? Power valves?
Open to suggestions.

 

[Demonracer]

What did the plugs look liked? Did you experience any detonation, back firing? We probably need more info on the motor; i.e. compression, heads and cam, valve train; i.e. springs, rocker arm ratio. Someone will chime in soon with their info on alcohol, I'm sure.

 

[bOb shingler]

reading plugs is a bit different than gas. you read them by the heat the cylinder is making. what you are looking for is the heat burn off of the cadium on the threaded base. ngk's work best for this. what will happen is the cadium will get frosty looking. take a pass and check all the plugs to see if the cadium is changing. keep leaning it out until you have no more then THREE threads burnt off. sneak up on it. timing is checked by the ground strap turning a bluish black. when it gets to the middle of the 90* bend that's enough.

 

[mikedevore]

Thanks for the replies.
The car ran really good.
Smooth, no surging or mis fire.
I was just a little concerned about the puff of smoke when it left.
Havn't looked at the plugs, only 3 passes on them, Autolite AR3911 race plug.

Engine, 414 CI, ported W2 heads, 1.6 rockers , Lunati Roller 640 lift, 12:1 comp., 34 degrees of timing.
I guess my main concern was jetting down from out of the box carb.
it had 144's in it & I put 142's in it. Is it common to go down on jetting?
Raced it back in November thru March (good air) with the 142's in it, it ran a best of 6.39 @ 105.

The car is very consitent, I ran a 6.610 & a 6.612, & my buddy ran 6.62 in it.

I understand I need to gather more details, but will need to get a few more runs on it.

 

[CHEATHAM]

id leave the fuel alone and bump the timing to 36 maybe even try 38, alcohal motors seem to just run good the richer they are, have a good ignition, change plugs often and check and change the oil often too, use a quality methanol.

 

[OldmanRick]

I have no experience with alcohol Mike, but I'm curious is to how it's leaving, meaning rpm off the brake? If it leave's hard off the converter, I'd think leaning the primaries is the way to go. If it's "flashing" the vert off a low rpm, I'd think the pump cam or nozzle could come into play with the early haze out the exhaust?

Just commenting for conversation...