Expert: Dan Liddy - 12/11/2009

Question
I race on a 1/4 mile oval dirt track. I run in a pure stock division with a 350 chevy and a holley 500cfm 2 barrel 4412. When the accelerator is slowly pressed the motor runs smooth, but if it is pressed to the floor rapidly there is about a 5-7 second hesitation, and almost stall, then it will kick in and rev up fine. Do you have any idea that i should check first to solve this problem? I have put a new remanufactured carb on it, in hopes of curing it, but it failed and is still hesitating. Thanks in advance.  

Answer
Hi Gary:

It sounds like fuel starvation. You should check your fuel pressure under load with a fuel pressure gauge.  Either cough up the bucks for the remote kind with a diaphragm between the pressure sensor and the gauge, or mount it OUTside the cockpit, in front of the windshield. In NO case should fuel be plumbed into the cockpit.

So while running all out you should have a minimum of about 4 Lbs. of pressure , if it goes lower during your acceleration , there is your problem area. It wouldn't surprise me to learn that your rules require a stock like mechanical fuel pump. If so, there are a few around that LOOK stock but have higher output. This may be what you need.

The other thing could be simple float adjustments. And keep in mind you are racing on a pretty tight track, fuel cold be simply slooshing away from the power valve(s).  Before going to a lot of expense, try raising your float level a bit. If it helps but doesn't solve the trouble , then see paragraph #1 above.

Let me know what you find. The problem interests me.

Thanks for writing !


Dan Liddy
Sarasota, Florida