Q jet Question
 

I had a new Magna Fuel system installed on a 69 Camaro stocker
I ran a test and tune today and the car was off as far as ET
I checked the fuel pressure and it was at 3 pounds
I brought it up to 6 pounds and the car stumbled on the launch and the 1-2 shift on the next run
I had always thought the fuel pressure for a Q JET should be at 7 pounds or so
Any thoughts on what might be causing this?
The car is very rich as you can smell the fuel all around the car when it is run

Re: Q jet Question
 

I remember in the manual with the magnafuel stuff I bought it reminds you to check the fuel pressure at an idle, not with the engine off. I also have heard several different people commment on how far off some of the fuel pressure gauges could be.

Re: Q jet Question
 

Check air door tension and float level.Could also be pulling fuel into sec.


Kevin

Re: Q jet Question
 

Mark,

Has the carb been apart for any reason, jets-etc ..?
Did you have a stumble/miss with 3 lbs of fuel pressure when you first started ? Sounds like maybe float or needle is sticking and fuel is bleeding by ? Is it clean driving around in pits & on starting line....? Maybe Danny will jump in if he is around ? Top of 1-2
shift usually points to flapper valve adjustment ? I would take carb
apart and check over really good, look for dirt or something in needle & jet area and make sure things haven't fall into bowls ...
Good Luck, keep us updated & talk to Vic Santos, he's very good with Q-jets.........

Re: Q jet Question
 

David

The car the 1st run ran fine but didnt run the number by a tenth
Thats why I checked the fuel pressure and it was at 3 pounds
So I turned it up
Running around the pits is fine the car starts up fine and runs fine

The carb has not been touched and has been perfect till now
I think it may be a bad pressure gauge

Thanks David for stepping in here to help it is kind of you

We had to turn it up alot to get it to 6 pounds and again there is alot of fuel smell
I will look for a gauge in the morning...

Re: Q jet Question
 

Mark, If using the big needle and seat (I think it is 0.135") in your q-jet, try running no more than 4-5 psi max, the float bowl will stay full. Higher psi never worked well on my 455 Pontiac either.
MWNorris

Re: Q jet Question
 

Mark,

I would try another gauge, if you can't find one , turn the pressure down to 4 lbs and see how that runs & feels ? If it works , it may get you by for this weekend .... If it doesn't work, adjust in 1/2 lb increments till it get better... Could try another carb ? Also , try ; turning on the pump & look down into carb to see if it's bleeding over with too much pressure ? ........... Good Luck .........

Re: Q jet Question
 

David

Good call the gauge was bad

Re: Q jet Question
 

Mark,

Glad you found your problem & congrats on your Win @ the Last IHRA event at NED ....