1st Gen Stock Carb, flooding?

J

JeffW

New member
I have almost been run over a couple of times on the track when this happens. Going into off-camber right-hand turns, I feather out of the throttle a little. When I get back on the throttle the car hesitates. The first couple of times it happened I was low on fuel near the end of a race. I started carrying a few extra gallons, thinking I was having a pickup problem. But it happened again. Now I believe that the carb may be loading up with fuel which is being dumped when I get back in the throttle. Has this happened to any of you?

I can think of some possible solutions.

1) Don't lift.
2) Lift completely, then mash the pedal.
3) Figure out what is wrong and try to fix it within the rules for RMDiv Spec7.

Diagnosis and correction help is needed.

Jeff
 
lower float level and or fuel pressure. takes a lot of experimentation to find the combonation that work best.
 
You didn't mention if you have a fuel pressure regulator installed. If not, install one and set pressure at about 2.5

I chased this problem for years and always assumed it was a fuel starvation prob caused by the turn. It wasn't...it was too much fuel caused by too high pressure...in this case, more is not better.

btw...u don't have to spend big $$ on a fuel pressure regulator. The little dial one from Purolator works just fine and I think is less than $20
 
First post in new format...havn't been here for a while...Please excuse any format goofs or multiple posts!!

I suspect your car is going lean, not rich.
I'm surprised it happens in right hand turns--the carbs are infamous for lean stumble exiting long left handers...

First off, make sure you have clean fuel filters, and that your float levels are at the correct heights (set to mazda factory manual height). It's also worth checking your needle and seats to make sure they are opening and shutting without sticking. I don't like any of the pressure regulators on the market. I run the low pressure holley unit, and I am religous about carrying a spare diaphragm for it. Although awkward to mount and adjust, it does seem to manage fuel pressure well.

If the hesitation is happening while rolling on the throttle, try increasing the stroke on the accelerator pump (adjust the little nylock nut on the long threaded shaft with the spring on it). Air flow through the carburator ventury sucks fuel out of the bowls, through the emulsion system and into the airstream. There is always a delay between airflow change and fuel flow change--that's what accelerator pumps are for. If you feather the throttle enough, the vacuum operatred secondary throttles can close (even at high rpm), when you roll on and they snap back open, it takes a moment for the fuel feed through the ventury to catch up--that's the hesitation. Increasing the stroke on the accelerator pump will put in more fuel while the throttles are opening.
Too little or too much stroke on the accelerator pump can cause hesitation while accelerating in a straight line. Count turns on the adjusting nut so you don't get it totally out whack as you try to tune it.

Good Luck
Tak
#29 ITA SFR SCCA
 
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