hey everyone, My 350 puts out maybe 350 horsepower. (Not REALLY sure though.) I can do a short full throttle run. But an extended full throttle run ends about at 100 with the motor falling on its face. As I have mentioned before, I have a rich/lean indicator and the motor is definately going "lean". I have been looking at electric fuel pumps all day and just can't seem to convince myself that I want to change the configuration of my fuel system, but I need a good mechanical pump that will support this motor and more. Does anybody have any experience with this? What pump do you recommend?
I have looked at the Carter- gm4690. It has a vapor return line. which is good. and says that the inlet and outlets are stock. That would simplify things. Puts out 5.5 to 6.5 psi and 120 gph with no load. Cliff Ruggles says my carb is set up to run at 6.5 psi. And he highly recommends going with an electric pump. But I'd be interested what you folks have found works well, especially if it meant I can keep my stainless steel "pump to carb" fuel line. Which looks nice and stock.
(I am presently running 5029N from National Parts Depot. Bought in 2002.)
Thanks for the input. Justin
PS. The all firebird show in Saratoga on July 11, was fun this year.
It's not the pump. It's also nothing new, and certainly not unique to your engine. This problem has plagued Q-Jets for 45 years. Do a search on "Q-Jet Needle and Seat." You can search this site or Google and you'll find out what you need to do.
Hey Quenton, When the carb was rebuilt Cliff put the larger needle and seat in. I don't recall what he recommends, but I'm sure it's in there. I'll do the search your talking about though.
Was this an originally a 2 or 4bbl car? My 2bbl car didn't come with a return line so If you don't have one either you're looking at replacing the sending unit also with that type of pump. I was having similar issues with my car a couple of years ago and went with a simple Holley Red mounted near the tank. Problem solved so far. I'm looking to get a spare to keep in the trunk because they say they don't last forever and I am not running a pre-filter so I may be running on borrowed time already.
I am experiencing the EXACT same issue with my car. At the top of 2nd and 3rd gear I run the bowl dry, fall flat on it's face, wait a split second then she comes right back and takes off like a mother. I was going to order a new higher volume fuel pump...
I have never taken apart a car carb but have rebuilt my motorcycle carbs, do they have an adjustment, bendable tab, for the float height in them also? If so you could lower the float in order to run richer.
The stock pump should be able to provide enough fuel as long as the needle and seat are big enough. More fuel pressure will also help but the main problem is the size of the hole that it is coming in through.
Robert, you were dead on. We tackled the carb today. A few months back when we rebuilt the carb we took out a 105 seat & valve and installed a 120. So today, we removed the 120 and installed a 135 seat and valve and bingo. Runs like a bear now!!! Thanks for the suggestion...
It costs $65 to run. Think the $40 entry for the weekend is included? Been a year and LOTS of beer since They put a # with shoe polish on your window. If you dont plan on racing, should get 2(maybe 3) trial runs Friday afternoon, and only 1 instead of 2 this year on Saturday and Sunday morn'ns.
