[Used2bfast]

Tech question.. new car running a stumble valve, when I got it the barrel valve was st 22%, I put it back to 14% as per engine sheet and it ran like a pig of the line. Do you need to run the barrel valve a lot richer when using these? Are they worth it or keep it simple and take it out? Sorry, hawk midget engine if that makes a difference. All other settings checked and set as per builders dyno sheet.

[jdperform]

Yes most time you will set barrel a touch richer. The stumble will generally be its most effective between 2500 and 4500 rpm. When used I do like to include a shut off valve for the stumble. It can help keep the motor a little cooler during yellows etc. to shutoff the valve. Also the driver can easily test restart response both using the valve and having it shut off.

[TQ29m]

Seems like everything comes and goes, what you never had trouble with before, suddenly becomes an issue. This may only work for me, but I removed the low speed bypass, idle bypass I call it, and eliminated it, I did set the barrel valve a tad richer, but also found that to make it perfect, I had to lead with the throttle a bit, just ride the brake a bit, and get a little throttle in it, before the green, worked for me, may not for you, I was also told that FI didn't work well on short tracks, especially indoors, mine worked great! Bob

[Used2bfast]

Thanks for that. I'm going to do away with it, if it stumbles, I'll put it back on and fatten up the BV a bit. The way it is set up with the main pill I would have to do some serious re-plumbing to put a shut off on it.
Thanks again for the responses, cleared up my line of thought on the issue. People here seem to be using but not understanding them!

[Used2bfast]

I ended up re-installing the stumble valve and put the BV back to 21%, the thing was a jet, thanks again for the advice. Then the brakes broke ....