Top end issue with drag car...

[mezmorized]

Hey, I thought I had asked this question here in the past but can't find the post.

I have been running a 78 Z28 with E85 for at least 3 years now. It runs great except when I play with the throttle at the top end to stay in front of my competitor. When I get off and back on the throttle, it's not clean, it's like it's running out of fuel maybe? I'm not sure anymore where to start. And as usual, I never have an issue in time trials since I don't pedal it at that point. And once in eliminations I don't want to touch anything.

[bigydaddy]

is it possible the pump shot from getting back in it is over-fuelling the engine? The carb is probably set fine for the top end with out the additional fuel from the accel pumps.

[mezmorized]

That is entirely possible, just really hard to check though. I think I have to train myself to stay on the throttle while using the brake pedal.

[triplenickel]

I would agree with bigydaddy that the pump shots may be adding too much fuel. It's possible that you're on the rich side of the fuel curve & the extra fuel from the pump shots is too much for it to handle. What I would try is to lean out the main jet 1 number front & rear & see how it effects the performance & the problem you're having when you "womp" the throttle. Also, double check your float levels & add a piece of hose from one bowl vent tube to the other & cut a hole in the middle at the top. Try this first before the jetting just to make sure that fuel isn't sloshing out of the vent tubes when you pedal it.

[mezmorized]

Thanks Triple Nickel, the problem isn't with the fuel sloshing out the vent because I have already been running a hose like you said between the vent tubes. I could very well be on the rich side since I haven't picked up a lambda gauge to see where I'm at.

I am starting to get a bit gun shy buying parts specific to E85 because of where I live, the availability is scarce. I live in Quebec near Ottawa Ontario Canada. First off, there are ZERO E85 stations in Quebec. Second, when I started using E85 there were 3 stations in Ontario offering E85, 2 in Ottawa and one in Peterborough (I think). Now there is only one left in Ottawa and absolutely no word if the one in Peterborough is still around or not.

So come spring, I will try and go 1 leaner all around on the carb and see if it helps.