CLASS RACER FORUM - View Single Post - fuel pump w/q-jet

Grant Eldridge · 01-01-2008, 05:15 PM

Kevin,
I can't tell you definitely if we picked up et or mph because we never did that kind of back to back experiment. We had been having problems with a high gear slight miss but not always. We had seen a drop in fuel pressure at the top end on our guage mounted on the cowl with the old system. The kind of problems we were having can be very hard to pin down, and I wanted to be sure we were not just on the edge with our system. Other racers had told me basically what I have told you, so finally I decided to "step up" and put in the good system. If you are just now building the car, the exra cost is not so bad. I had to replace all my stuff with better parts and add the entire return system and plumbing.
Since then I've added an EGT and then an O2 data logger to get more data. Even with this fuel system in high gear you can see that the fuel curve is not steady but goes richer and leaner as you go through high gear, maybe .4 or .5 fluctuation. I've been wondering if there is anything further I can do to get the fuel curve more even. If anyone has an idea, please chime in! You are really battling to get enough fuel through that .140 needle and seat and keep that one small fuel bowl filled. I would not switch back, you need as much fuel volume as possible available to the carb in my opinion. I run E/SA or F/SA so possibly your demand will be a bit less, but why not do it once and make it as good as possible?
To get the AN-12 to attach to the Q-jet carb I took a stock inlet fitting and drilled it out, tapping it to a larger pipe thread. I threaded in a 45 degree brass elbow that I ground down externally to clear the carb body and then was able to use a hydraulic fitting to go male pipe thread to AN-12 male. I enlarged and contoured the internal size of these fittings to ensure no restrictions. You might be able to come up with a more elegant solution, but this will work fine. Here's a link to a photo of what I'm running:-

http://i228.photobucket.com/albums/e...acecar0012.jpg
Good luck with your stocker! It is all about attention to details like these and using nothing but the best parts, It's also a great challenge to try and make the combination work better all the time.....

01-01-2008, 05:15 PM	#6
Grant Eldridge Member Join Date: Jul 2007 Posts: 124 Likes: 0 Liked 0 Times in 0 Posts	Re: fuel pump w/q-jet Kevin, I can't tell you definitely if we picked up et or mph because we never did that kind of back to back experiment. We had been having problems with a high gear slight miss but not always. We had seen a drop in fuel pressure at the top end on our guage mounted on the cowl with the old system. The kind of problems we were having can be very hard to pin down, and I wanted to be sure we were not just on the edge with our system. Other racers had told me basically what I have told you, so finally I decided to "step up" and put in the good system. If you are just now building the car, the exra cost is not so bad. I had to replace all my stuff with better parts and add the entire return system and plumbing. Since then I've added an EGT and then an O2 data logger to get more data. Even with this fuel system in high gear you can see that the fuel curve is not steady but goes richer and leaner as you go through high gear, maybe .4 or .5 fluctuation. I've been wondering if there is anything further I can do to get the fuel curve more even. If anyone has an idea, please chime in! You are really battling to get enough fuel through that .140 needle and seat and keep that one small fuel bowl filled. I would not switch back, you need as much fuel volume as possible available to the carb in my opinion. I run E/SA or F/SA so possibly your demand will be a bit less, but why not do it once and make it as good as possible? To get the AN-12 to attach to the Q-jet carb I took a stock inlet fitting and drilled it out, tapping it to a larger pipe thread. I threaded in a 45 degree brass elbow that I ground down externally to clear the carb body and then was able to use a hydraulic fitting to go male pipe thread to AN-12 male. I enlarged and contoured the internal size of these fittings to ensure no restrictions. You might be able to come up with a more elegant solution, but this will work fine. Here's a link to a photo of what I'm running:- http://i228.photobucket.com/albums/e...acecar0012.jpg Good luck with your stocker! It is all about attention to details like these and using nothing but the best parts, It's also a great challenge to try and make the combination work better all the time.....