Small Block & Big Block Chevy Specific - carbed f body help please
11-03-2009, 01:14 PM
I have a ported head vortec 350 with a nice hyd roller camshaft in my 96 Firebird. The other day I had some trouble with the carb loading up really rich when I cam to a stop and the car died. I killed the ignition whitch in turn kills the fuel pump and got out to asess the situation. When I pulled the carb scoop off I realized that fuel seemed to be boiling out of the venturis and idle air bleeds and into the motor.
Has anyone seen this before? Do you think that lowering the float bowls might help at all?
Any suggestions taken seriousely.
11-03-2009, 01:23 PM
You might have trash in the needle and seat, or to much fuel pressure. I wouldn't run more than 6 psi. Don't let anybody tell you any different. I run 5 in my drag car and it runs mid 10's. Also, do you have a heat sink spacer betweend the carb and intake. If not you might think about putting one on. The carb may be getting hot enough to boil the fuel out.
11-03-2009, 01:31 PM
I still have the factory style fuel filter in place even with the edition of the holley blue pump. The fuel tank is absolutely spotless last I was in it and when I encountered the problem the pump had been shut off for atleast a good minute. I do not have a thermal spacer due to hood clearance. I have a plate shot under the carb and a 2000 s10 blazer tb scoop that I modified to fit a carb and the hood wouldnt dare close if it was the slightest bit taller.
If it were a boiling problem do you think that lowering the float would decrease the problem?
btw I due have a fp gauge and its at 5.5psi
11-03-2009, 05:22 PM
Probably not on the float level. You are really going to need to cool it off somehow. Might try to take the plate off and use a FelPro gasket #60123 ( I think that is the #). It's about a 1/4 thick 4150 Holley style gasket. I would imagine that you have a square flange carb on there. Just a guess.
11-03-2009, 09:30 PM
Yes I really think we are on the same page here. The under hood temps are insane im sure. I use a !" thermal spacer on the motor in my Cutlass and the carb by touch is generally half the temp as the intake manifold.
11-04-2009, 07:28 AM
Might try one of these. Ice doesn't last very long, but will help see if that's the problem. For the price, I would try to borrow one.
11-04-2009, 09:55 AM
LOL I was thinking the same thing but what a neuscense it would be to have to buy a bag of ice everytime I wanted to drive my 12 second street car.
11-04-2009, 11:21 AM
Has this always been an issue with the current setup? If it's been running fine for some time and just recently did this, then I'd have to say it's not related soley to an overheating carb (unless it was much hotter out than usual, where you live).
It's pretty common for a little pressure to build in the bowl after engine shutdown when the carb (and fuel in the bowl) becomes heat soaked. Ideally, there shouldn't really be any liquid fuel leaking, but a tiny bit of air pressure hissing from the boosters can happen.
But if you have fuel pouring out of the boosters or bowl vent while idling (or immediately after engine shutdown), and fuel pressure is dead-on, then something is wrong with fuel level in the bowl, either due to an issue with the float setting or there's dirt/clog somewhere.
Again, is this a brand new problem with a setup that previously worked well? And what brand of carb is this?
11-04-2009, 11:30 AM
What about running a return line back to the tank, wouldn't that maybe help keep the temps down on the fuel so it isn't just sitting in the line absorbing the heat??
Just a thought.
We used to run a really cheap inline fuel filter from a 77 Jeep Wagoneer with a 360 V8, the factory in-line lifter has a outlet built on it that is a return outlet.
11-05-2009, 07:15 AM
its a Quickfuel 850 mechanical. The setup has only been together for a couple months and I been working so much I havnt driven it much but the other day I drove to watch my friends car get tuned at Ramseys and it was basically the longest drive the car has been on thus far (about 30 miles one way) and on the way home the car shut off at a light and the wideband was reading 9.00 and the venturis were filled up to the boosters with fuel. and then it was kinda bubling out of the airbleeds and that sorta thing. I think its a mixture of float level and heat expansion. Hasnt really done it to me again this week though its been alot cooler. But I been driving it to and from work with no problems.
11-05-2009, 09:52 AM
Are you running a return line on your fuel system??