87Stallion

I have just converted to carb. I am running a RPM Air Gap manifold,670 Holley Street Avenger Carb, 85 GT Dizzy and the Duraspark II ignition box.

All above parts are new except for the ignition box.

Problem is the car runs fine sitting in the garage. I can hit the throttle and its very crisp and responsive but soon as I get in and go for a drive it stumbles and falls on its face. No b@lls at all.

I have re-stabbed the dizzy about 20 times. I know the timing is right. I've tryed 10* 12* 14* and 15* and there's very little difference. I have also triple checked the firing order.

The fuel pressure is good at 6 psi.

Any ideas? Could this box be going bad as it is used.

87Stallion

Just a update. I checked for vac leaks and none were found. Have a steady 17 hg vacuum. I am about to just start this bitch on fire and burn it 2 the ground.

aode08

what kind of distributor are you running?


what are your mods, and do you stil have a computer running anything?

holyshift

Are you sure your not losing fuel pressure when you go to put a load on it? Cause free revving is one thing, with a load on it its gonna be different. I just converted to carb as well and i tried to tap into my stock fuel lines and yadda yadda well when i went to the track it lost fuel pressure a little past 60 ft. and then would die at about 1/8 mile...so a fuel cell is in now....just an idea look into it. My car was the same way until the cell went in.

Oh and i run mine at 7psi, dunno if that makes a diff???

87Stallion

I am running a stock brand new 85 Mustang GT dizzy. No computer at all. I am running GT40 X heads and stock cam and full exhaust no cats. All computer **** has been removed.

I tried 7 psi also and it was no better. I have a guage on my regulator but I cant see it going down the road. How would one determine that.

mjr46

have you tried a different carb for the heck of it?? I'd see if you can borrow a 650 double pumper with mech secondaries from someone, are the secondaries opening on the carb you have??

holyshift

Mounting a Fuel pressure gauge on your cowl panel would be the best thing, those little gauges that come with regulators and stuff i dont really care for, thats just my opinion but yea like Mj said maybe a different carb., my first one i bought from a dude was a piece of crap and i had to trade one of my buddys but its all good now...but fuel pressure is still something id look into

87Stallion

Yes I did the paper clip thing on my carb. They are opening. Mine has vacuum secondaries. I dont think its a secondarie issue. It falls on its face at 15 mph. As soon as I put it in gear and let off the clutch it goes to ****. It doesn't stall but it runs like I got 2 plug wires off.


I bought a complete 289 from carb to pan, So I will take the carb off it and try it. But my carb is brand new. I doubt its a carb issue. But I could be wrong. Its been known to happen.

I adjusted the carb as per the holley tech. I set the air/fuel ratio based on max vacuum.

mjr46

if anything once set up right that car should run a tad faster not worse

87Stallion

I know thats why I am so disappointed. Its not like its a motor issue, the car ran great before the conversion. Thats why I was wondering if it could be the used ignition box I used. Everything else is brand new.

Will this happen if the carb is too big for my engine? I know I need to put smaller jets due to the elevation here. The carbs are calabrated at sea level. I am at 3200 feet. The holley tech said go down a jet size for every 2000 feet above sea level.