Starving!

R

rx7chris

New member
This past weekend was my first race weekend. I learned a couple of things, the most frustrating was the fact that in left hand sweepers, sometimes in the right handers, my carb would run out of fuel. it would pick up fine on the straights. i could catch cars on the straight and watch them walkaway in the corners because of this prob. has anyone ever experienced this. IT7 79 carb, 85 motor, carter fuel pump, summitt cell. the course was the Sebring Full course.

On another note, what rear gear is everyone using?

Thanks for the help
Chris
IT7 #88
 
Ultra Common, it will happen.. I had mine built by a guy I know in Chicago referred to me by an old IMSA RS Rx3 racer Chuck Ulinski, but I don't remember what he did. YAW Power, and Heintz, and Mzdatrix all offer a service to fix this.. If the talented Mr. Lemon knows what to do maybe he can tell you.

Welcome to the club! It's a wonderful thing, racing, isn't it!

K - damn I miss it...
 
as Kieran says it is common. I know Paul Yaw in Arizona sells a carb to fix the problem, that is what we have, but I am sure mazdatrix will also be able to help you.

Dick Plank
 
The problem is usually caused by too much fuel in lefthand turns. Cliff notes:

Run as low a fuel pressure as you can. Stock float needles should get around 2 psi.

Don't trust a 0-15 psi gauge to be accurate at 2 psi. It won't be. Find a really good gauge that is properly calibrated and leave it in your toolbox. Or, without blowing anything up, build yourself a gasoline manometer. Gravity never changes...

Put your fuel pressure regulator right behind your carb on the firewall. If its on the driver side fenderwell, you get an extra psi or so in left hand corners.

Consider running 2 regulators in series if problem persists. Make sure the regulator is supposed to work at 2 pounds, and then distrust it anyway.

Set your float levels slightly low.

Lean out your idle circuit as much as practical.

Lean out your accelerator pump shot as much as possible.

You might want to do a search through the race carb section over at www.mazspeed.com also.
 
Chris,

Im sure Mike at ISC can help you with your carb issue. I would also bet most everyone in IT7 is using either a 4.88 or a 5.12 rear gear. Mike can help with that also. Call him at 863-324-2742.

You can also try Andy Gustus. He is in Orlando and races an IT7 car also. Call him at 407-384-9820.

Was that one hell of a weekend or what. Beautiful weather, tons of good cars and a track that was FAST. I bet every class set a new lap record, probably due to the repaving from turn one to turn seven.

Happy racing



------------------
Marc Dana
#63 ITS Mazda Rx-7
#77 STS BMW 325I
 
Chris,

I feel your pain. I struggled with this for years. I had a fuel pressure regulator in the car and would see the pressure drop to zero and the car sputter. In my case, a stock fuel tank, it was in right handers. Not enough fuel, increase the pressure on the regulator, right? Wrong! Dialed it back to 2# and problem fixed...never occurred since. Once again, DDamouth hit upon the solution. Puralator's regulator I think only costs less than $10. Of course, keep your fuel filter clean as well.
 
I had the same problem until I put in one of the Purolator regulators. They're not terribly accurate, so you may have to experiment with the setting. Mine works at 3.5 psi, but I've never put a guage on it.

Hey, Marc, great to see you this weekend. Hope I didn't hold you up on Sunday. I knew you were chasing Mike, so I tried to make room.

What a gorgeous weekend! 70 or so cars made for entertaining starts, but the racing was great, the long course was a blast, and despite losing 5th gear on Sunday, I had a great time.

Ed
IT7 #68
 
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