Scott,
I'm new here, but Ive been posting articles with Mazspeed for several years. I have also woked closely with Paul Yaw and we run his carbs on my Solo car and the ITR Mazda I crew for.
Several things come to mind with your problem:
If you have your fuel pressure regulator mounted to the left of the carb, as many people do for convenience, you will have a stumble in sweeping turns. Move it directly behind the carb (it's a tight fit) and keep the hose run as short as possible.
The Holley (Summit) regulators have a bad habit of pressure creep. Add that to most aftermarket guages being WAY off, and I can assure you your are running too much pressure. We have found that 1.75 psi is ideal. Yaw sells a certified gauge for about $50 that is dead-on. There is no brand name on it, otherwise I'd tell you who to call. You can search for gauges. Try to find a certified 1-15 psi unit rated at +/- 5% acuracy.
Last, Grose jets are VERY poor inlet devices. A standard needle and seat lapped with extra fine compound works well. Use the spring loaded type like the originals. These come in the factory carb kits. Set float height to .62 in. using a dial caliper. This MUST be dead on to get good results.
As a fuel specialist, I can assure you good results. Unfortunately, I can no longer endorse Paul Yaw. His customer service has become unacceptable. That's a shame, since he builds a damned good carb.
bobrx7
Crew Cheif
#46 ITR, WHRRI,
Novi, MI
And I must say that I ran faster than I did in a lapping day, where I noticed the left hand stumble in turn one, but did not notice the stumble this time running 3/4 tank of gas. So I guess my solution for now will be a few dollars/pounds of 87 octane gas. Hopefully I will out grow this patch (ie faster) and will be forced to find another.
