Too Slow/Q-Jet question

[a pontiac]

You need to try another q-jet for comparison, I thought I had a good one, borrowed another and was 2 tenths quicker. Also, most jet tuning is with secondary rods.

[Mike Jones]

What Model is your 1980 Chevrolet?

[Adger Smith]

I'm not a real Q-Jet tuner, but I question the 6.5 lb fuel pressure.
N/S area vs the small float
What do the experts say about that?
I have had Q-Jet customers that are very particular about regulator location and fuel line routing to the carb...
OK What you say Q-Jet experts??

[Mike Pearson]

Originally Posted by Adger Smith

I'm not a real Q-Jet tuner, but I question the 6.5 lb fuel pressure.
N/S area vs the small float
What do the experts say about that?
I have had Q-Jet customers that are very particular about regulator location and fuel line routing to the carb...
OK What you say Q-Jet experts??

6-6.5 PSI is what I run for fuel pressure. You need minimum 1 gallon of fuel delivery at the carb in less than 30 seconds. I run a Magna Fuel regulator dead head with #8 line from the cell to the carb. Regulator is mounted on the fenderwell I have one of those Chinese summit pumps that is similar to a holley blue pump. I have run 9.90 with my set up. My carb was built by Jim Boburka.

[Cdncarnut]

I have 2 spare Q-jets in my trailer, plus the one on the car, built by the 3 major builders, two of whom have now retired.

I have actually had a case where a carb ran great two weeks ago, would not qualify the car.
Yet, the carb which ran like poop 2 weeks earlier, ran the best ET ever.

I also have one which will get my down the track, significantly under the index, every time.

Getting the rods and hanger correct for race day can be a challenge.

There is no easy answer and really no cheap solution.

[JP1738]

Originally Posted by Cdncarnut

I have 2 spare Q-jets in my trailer, plus the one on the car, built by the 3 major builders, two of whom have now retired.

I have actually had a case where a carb ran great two weeks ago, would not qualify the car.
Yet, the carb which ran like poop 2 weeks earlier, ran the best ET ever.

I also have one which will get my down the track, significantly under the index, every time.

Getting the rods and hanger correct for race day can be a challenge.

There is no easy answer and really no cheap solution.

Well cheap is relative lol, but I'm learning quickly that's a far fetched idea in this class. No big deal, I still think I can be at the track even with a few minor upgrades for less than 13 large.

[JP1738]

Originally Posted by Mike Pearson

6-6.5 PSI is what I run for fuel pressure. You need minimum 1 gallon of fuel delivery at the carb in less than 30 seconds. I run a Magna Fuel regulator dead head with #8 line from the cell to the carb. Regulator is mounted on the fenderwell I have one of those Chinese summit pumps that is similar to a holley blue pump. I have run 9.90 with my set up. My carb was built by Jim Boburka.

Have not checked flow from my pump, but I'm going to check that today too. Mine is a Holley Blue pump but it's ancient. -6AN line from regulator to carb through an inline filter.

[Mike Pearson]

Originally Posted by JP1738

Have not checked flow from my pump, but I'm going to check that today too. Mine is a Holley Blue pump but it's ancient. -6AN line from regulator to carb through an inline filter.

All that should work if it’s mechanically in good working order. Check the flow before and after the filter. If the flow is low with the filter you might need to take it off. I do not run a filter and never have. I am real careful to keep my fuel system clean.

[JP1738]

Originally Posted by Adger Smith

I'm not a real Q-Jet tuner, but I question the 6.5 lb fuel pressure.
N/S area vs the small float
What do the experts say about that?
I have had Q-Jet customers that are very particular about regulator location and fuel line routing to the carb...
OK What you say Q-Jet experts??

I also have an inline fuel filter after the regulator between that and the carb. Tim Stick advised I 86 that and he's probably right. I put it there because the car had been sitting for a long time and there was a bunch of gunk and trash in the tank and line. I cleaned and flushed everything best I could, but I stuck a filter on it to catch anything I missed just to be safe. I plan to remove that as soon as I get to work on the car again.

[Danny Ashley]

[QUOTE=Adger Smith;692814]I'm not a real Q-Jet tuner, but I question the 6.5 lb fuel pressure.
N/S area vs the small float
What do the experts say about that?
I have had Q-Jet customers that are very particular about regulator location and fuel line routing to the carb...
OK What you say Q-Jet experts??[/QUOTE


Quadrajet fuel pressure depends on the needle & seat size. They are available from .110 - .150. The .110 can handle more pressure than the .150. My choice is the .135 for all applications. It has been used in two of my Super Stock customer's cars who have run in the 8 second zone. You can safely run 6 - 6.5 with it but I have fast customers who only do 5 - 5.5. You will have more problems with too much pressure than too little. A well designed fuel system will go a long way in not creating problems you may attribute to the carburetor. Locating the regulator ahead of the carburetor and allowing inertia to work for you is a plus.