Inconsistent stumble CONVERTER?

Guys I run a super comp car and have to get on the throttle as soon as I Stage the car. The problem is that the car stumbles most of the time. I had the problem for a while but have since switched to a different carb (E85) and noticed that it still does the same thing. Spent Saturday messing with it and think now it really maybe a Torque Coverter problem, It seem that I can hit the trans brake and then stab the gas and it would go straight to 4000 rpms then stumble and spits its way to 5000 rpm. The converter use to stall to 5600 that I recall.

So I'm pulling it out today and putting in my back up converter and will try that. Don't know that I'll test it here at the house as I respect the neighbors for the noise as much as possible.

Ace

I have seen a broken sprag act like that.

dkp

How's the ignition system?

Its all MSD. 7AL3 box with the Zero chips in the retards, Dist is lock out and timing is set at 36˚ wires were new last year.

Ace

Have you been running the 7AL-3 all along? If you've switched from a different box, you might find a rotor phase adjustment is necessary. A friend and I chased that gremlin when switching from 6AL and 7AL-2 boxes to the 7AL-3. Just something to check. Good luck with it.

Valvetrain?

I've been running the MSD stuff on this car since new in 2000. What I found out was 1 there something wrong with the converter. The Identical replacement now stalls to 5700 rpms Like it should, not 5000 rpm's. Now the stumble is the carb as the richer the mixture just in the Idle circuit makes the stumble happen sooner(3000 rpm's vs 4000 rpm's). So I'm trying to set the carb back up to the original spec's when I started this E85 deal. The plugs are looking pretty black. So I would say I'm fouling the plugs at Idle. I have an Innovate LM2 and found out this thing is not reliable in any way. Biggest thing is I don't think the sensor is deep enough to get any accurate readings and because of the location in the collector it has a lot of reversion ( cam shaft profile) pulling in fresh air at an Idle to get any good readings.

I'll keep you posted


Ace

Idle Mixture isn't super critical other than to keep the plugs clean.

Ace, on my LM2 I had to add a 8" pipe after it to make it work correct same issue your having. You need to check our rotor phasing, and mine loves 34 degrees , also I closed the plug up a little to 35. I also had a stumble when I first went to E85 and it was fixed by some of these issues. I still had a little one and I started going up on the squirters untill it was gone then increased the idle air bleed size to lean it out. Run it lean at idle and adjust squirter to take the stumble out. I found it hard to tell if it was lean or rich untill I took a big swing at it too see the reaction. If you plugs are black its way too rich.

BIGDOG466 wrote:Ace, on my LM2 I had to add a 8" pipe after it to make it work correct same issue your having. You need to check our rotor phasing, and mine loves 34 degrees , also I closed the plug up a little to 35. I also had a stumble when I first went to E85 and it was fixed by some of these issues. I still had a little one and I started going up on the squirters untill it was gone then increased the idle air bleed size to lean it out. Run it lean at idle and adjust squirter to take the stumble out. I found it hard to tell if it was lean or rich untill I took a big swing at it too see the reaction. If you plugs are black its way too rich.

We need to talk. I have a lot of questions you might be able to answer for me. Send me a pm with your number so i can call sometime this weekend and we can talk.

Thanks
Ace

converter guy called and said the spragg was bad. So the story goes on

Ace