Starting line hesitation
 

I have a 80 Camaro 350 H/SA that I am having a problem
with. When the car leaves it goes 2 ft and it sounds like the engine
cut out for a tenth of a second for the last 6 runs. The 60ft times
are exactly a tenth slower the last 6 runs, at 2 different track But the
mph is the same as before this problem.
I have a 2 step and I tried with it hook up and not hook up, no difference
ANY HELP APPRECIATED
BOB KELLER

Re: Starting line hesitation
 

More info might help. What RPM do you leave the line at? What is the fuel psi before you stage ? What is the fuel psi when it cuts out? Does it recover Quick or slowly rev back up. Have you had the top lid off the q-jet to look inside? Possible fuel psi regulator problem. Or might be ignition miss

Re: Starting line hesitation
 

Possible fuel spillover on launch?

Re: Starting line hesitation
 

Which carburetor? Qjet or Holley?

Re: Starting line hesitation
 

It's either fuel spill over, bad choke pull-off, or secondary door to loose.

Re: Starting line hesitation
 

If it is a Q-Jet could be spill over from too high of a fuel pressure setting.

Re: Starting line hesitation
 

Thank you all for your come backs. The car has a 3700 RPM
chip in the 2 Step. Fuel pressure on line is 6 lb.The engine
recovers quickly. The last run it did it twice one after another.
This is a Danny Ashley Qjet built in 2012 I don't want make any
adjustment to the carb. The carb work great before.
. I removed the top to install plugs in carb because I
am now running a two step.I removed the plugs and used the foot
brake, same thing. I also installed a lifter valley baffle could this
ad to the problem
Thanks for your time
Bob Keller

Re: Starting line hesitation
 

Since Danny built it, I am ruling out the air door to loose. I would try a new choke pull-off, I have had several of them go bad and cause the same issue. Pull the vacum hose off and push the arm in, with the arm pushed in hold your finger over the vacum port. Let go your finger off the vacum port and make sure the arm comes out smoothly. If it starts coming out and then hangs up for a second it's bad.

Re: Starting line hesitation
 

Bob,
Is the brass plate for metering rods in place? If that slips forward when changing metering rods it will bog with spill-over. Also check choke pull-off.

rod

Re: Starting line hesitation
 

That is the problem which I had...
I did not know that it was there and, when I pulled the secondary rods to measure them to resolve a rich condition, it slipped forward.
I could not understand how a car, which ran fabulously just two weeks before, could now stall after my burnout and hesitate so bad off the line.
As it was my first experience with a Danny Ashley carb, I did not find it until I pulled the top off.

Re: Starting line hesitation
 

Let us know if you figure out the stumble in your carb. We have a Danny Ashley prepared Q jet that does the same thing and we have not been able to get it fixed. It's a real nice carb and Danny does nice work so we would realy like to get it running right.

Re: Starting line hesitation
 

In the instruction from Danny that come with The carb it said
that the brass plate fit in a machine groove in the carb top
and I have double check the plate and it is in the groove.
If I find a answer I will post it.
Thanks for everybody's help
Bob Keller

Re: Starting line hesitation
 

Don't you guys think 6 psi. of fuel pressure is a bit low? We had a Dean Oliver prepared carburetor and currently have a Hedworth prepared unit and we ran both carbs. at 7 psi. and both perform nicely. Is it possible momentary fuel starvation is occurring considering a Q-Jets float bowl is so small?
Just a thought.

Re: Starting line hesitation
 

Fuel Pressure is related to the size of needle and seat, and float settings and of course demand. I need to run mine at 5.5 for best operation , anything over 6 and - too many issues

Re: Starting line hesitation
 

Mine runs good at 6 lbs too.

Re: Starting line hesitation
 

I am running a Joe Scott at 7 psi with no issues.
My Ashley was also running at that same pressure.

Re: Starting line hesitation
 

I have run ours at pressures of 6 to 7.5psi without issue...currently at 6.5psi.

Re: Starting line hesitation
 

I'm really not getting how you could bind up that secondary plate deal.
The last thing you would do is set the metering rod tips down into the fixed jets.At that point the hanger would be down flat on the cam arm. You can slide the whole deal fore and aft to check everything before you put the hanger screw in place.

Danny did a nice job on that deal. I never did get that fancy. I just took a small chunk of a Walmart bag and cut a couple of x's in it, then stuck it down to the gasket with a spot of chewing gum until I got the top was screwed on.
That works fine ,and doesn't restrict or bind the swing of the rods like the old tape trick did.

Re: Starting line hesitation
 

Just in case... check the accelerator pump. Every time mine hesitates or stumbles off the line the gasket is dried out from sitting, torn or worn out and doesn't seal because of VP eating at the gasket. Q-Jets do not like a lot of fuel pressure so 6 to 7.5 is fine. You can play with that but not is why it is hesitating in my opinion. Let us know so we can learn, Q-Jet are great but can make you crazzzzy.

Re: Starting line hesitation
 

I would say your gasket is bad like Joe said, or needle and seat is leaking. My car has done that before,finally figured out it was needle and seat, I have them leak,but they don't pour fuel out of it,they will leak slightly,car will idle about 200-300 rpm slower,and bogs a few feet out.
The best test I have come up with is remove top and hold float pivot rod with your finger so float works like the top is on carb,then have someone turn on fuel pump, after needle and seat closes watch fuel level in bowl for 1-2 minutes,it should not creep any higher up at all,it may take a minute and if leaking will rise very slowly, be careful sometimes when first turn on pump it will spray fuel out,I usually use my other hand as a shield over carb,till it calms down.
The best thing I have found to prevent this problem is to run carb dry and pump fuel out of tank when I get down racing and store the car,even for one week.
Mark,
I still use the tape trick, I use 3M super33 tape is a soft and flexible electrical tape.

Mike Taylor 3601