Moparts
Why does my car stumble in the air?
Posted By: 572_dup2
Why does my car stumble in the air? - 08/30/09 06:26 PM
Would it help to put jet extenstions on? Carbs are sideways. Fuel pressure is 6 1/2 an use 4 port magna fuel. Or just maybe set the floats little higher? An thoughts?
Thanks
Posted By: 408strokerdart
Re: Why does my car stumble in the air? - 08/30/09 06:32 PM
Not sure jet extensions will help, but you might be able to cure some of the problem with raising the floats some?
Posted By: 572_dup2
Re: Why does my car stumble in the air? - 08/30/09 06:45 PM
It does it on every pass just before i shift into 2nd. If it did it once or twice maybe think its a fluck. Do you think fuel pressure needs turned up too?
Posted By: Quicktree
Re: Why does my car stumble in the air? - 08/30/09 06:50 PM
turn the fuel pressure up to 8 at idle. and check the bowl level
Posted By: Al_Alguire
Re: Why does my car stumble in the air? - 08/30/09 07:03 PM
Calm down the wheelstand, I know that is not what you want to hear but it is probably the RIGHT way
Posted By: 572_dup2
Re: Why does my car stumble in the air? - 08/30/09 07:12 PM
Best 60's ever all 1.28s. Got the bump stops set as tight as im gunna set them. Leaves the best around 2000rpm. Sounds like an feels like its starved for fuel right before 2nd an then after i shift it takes it a little time to recover.
I have video i will show as soon as the get it to me.
Posted By: Anonymous
Post deleted by Defbob - 08/30/09 07:36 PM
Posted By: cudabunch
Re: Why does my car stumble in the air? - 08/30/09 07:39 PM
What fuel pump are you using and is there a air filter on the carbs ?
Posted By: Anonymous
Post deleted by Defbob - 08/30/09 07:59 PM
Posted By: 572_dup2
Re: Why does my car stumble in the air? - 08/30/09 08:04 PM
Magna Fuel 500
Posted By: sixpackgut
Re: Why does my car stumble in the air? - 08/30/09 08:13 PM
standard floats will close the needle and seat when fuel sloshes back
Posted By: MegaDart
Re: Why does my car stumble in the air? - 08/30/09 08:14 PM
a voltage drop can slow you fuel pump down too
Posted By: Al_Alguire
Re: Why does my car stumble in the air? - 08/30/09 08:29 PM
How long and high is it in the air? Maybe it is possible you are up long and high enough to uncover the front jets in carb long enough to cause and issue. Maybe some sort of modified jet extensions are in order? Have you watched the fuel pressure to see what it is doing? I know that is easier said than done while driving a car in the air but might take a peak.
Posted By: 572_dup2
Re: Why does my car stumble in the air? - 08/30/09 08:58 PM
Dont think its a voltage thing. Im back to 2 battires now.
Fuel pressure in high gear is around 6 61/4. But it dont now what fuel pressure is off the line?
Im going to cut 2 holes in the front of the cowl to let some air in. Its a piece of trash in high gear. Runs less MPH than it did before, but the 60' is best 1/8 mph is up some an 1/8 et is getting better. This should fell like afterburners kicking in!
Posted By: Cab_Burge
Re: Why does my car stumble in the air? - 08/30/09 09:12 PM
Is it possible that fuel is sloshing into the carbs form the vents? I had that problem with my six pak and didn't realise it for a long time
Posted By: pittsburghracer
Re: Why does my car stumble in the air? - 08/30/09 09:17 PM
Shawn how close are your carbs to the top of your hood scoop? I had to take my tunnel ram off because mine were to close and would shut off air flow to the carbs.
Posted By: 572_dup2
Re: Why does my car stumble in the air? - 08/30/09 09:17 PM
could be possible? But we didnt see any sign of fuel coming out? It fells like it starts this when the car is at its highest. But it happens so fast sometimes i forget. LOL
Im hoping the video shows signs of whats happening.
Posted By: Challenger 1
Re: Why does my car stumble in the air? - 08/30/09 09:22 PM
Injection will take care of it, Think what it'll look like with stacks sticking thru the hood!
Posted By: Cab_Burge
Re: Why does my car stumble in the air? - 08/30/09 09:26 PM
I think the fuel in the carbs. is held down by gravity while the car is going up and once it starts to slow down going up the fuel will be released from the graivity and rise up in the fuel bowls and possibly slosh out thru the vents
I used three peices of rubber hose and routed it to the rear of the air cleaner base, on my tunnel rams I'm going to use two vacume tees per carb and hook them onto the vents with a short piece of hose and connect the vents in line and leave the ends open on both ends. I should make one up and take a picture and post that instead of trynig to describe it in words
Posted By: gregsdart
Re: Why does my car stumble in the air? - 08/30/09 10:02 PM
Quote:
How long and high is it in the air? Maybe it is possible you are up long and high enough to uncover the front jets in carb long enough to cause and issue. Maybe some sort of modified jet extensions are in order? Have you watched the fuel pressure to see what it is doing? I know that is easier said than done while driving a car in the air but might take a peak.
Look at the highest angle you get the car up to, then add about thirty degrees for acceleration, maybe more. Look at a float bowl at that angle and you can see what is happening to the fuel. I bet the custom jet extensions will do it.
Posted By: Anonymous
Re: Why does my car stumble in the air? - 08/31/09 12:55 AM
Quote:
Best 60's ever all 1.28s. Got the bump stops set as tight as im gunna set them. Leaves the best around 2000rpm. Sounds like an feels like its starved for fuel right before 2nd an then after i shift it takes it a little time to recover.
I have video i will show as soon as the get it to me.
had the same problem today, my car was leaving hard and pulling up the frontend causing my jets to be uncovered causing a lean condition.
i raised my floats up on both carbs a bunch with a drill bit and problem solved. got my best et ever in bad air.
dont touch your fuel psi, thats not your problem.
Posted By: Anonymous
Re: Why does my car stumble in the air? - 08/31/09 01:00 AM
jet extentions wont help with sideways carbs.
Posted By: MR_P_BODY
Re: Why does my car stumble in the air? - 08/31/09 01:21 AM
Quote:
jet extentions wont help with sideways carbs.
A set of 90% bent tubes would so the ends are at the
rear of the carb(what is the rear now)... might be
able to use a short piece of fuel hose to connect
them to the jets.... I'd do all of the jets to make
sure they are all getting fuel. This should work for
a test and if it corrects the problem then I'd make up
something that would be a little more permanent.
Also the comment of being slower in high gear...
it could be a air issue... put a air pan on first
that may knock out some of the hot air thats up in
the cowl(thats where its trying to escape to)
Posted By: Chris'sBarracuda
Re: Why does my car stumble in the air? - 08/31/09 01:27 AM
The first thing I would do is make a pass with the hood off..
Chris..
Posted By: hemi-itis
Re: Why does my car stumble in the air? - 08/31/09 01:30 AM
To eliminate the hood as an issue,make a pass without the hood on
Posted By: MR_P_BODY
Re: Why does my car stumble in the air? - 08/31/09 01:39 AM
Quote:
To eliminate the hood as an issue,make a pass without the hood on
I believe he did(in his hood post) and really slowed
Posted By: 572_dup2
Re: Why does my car stumble in the air? - 08/31/09 01:41 AM
slowed down when i took the hood off.
Posted By: MR_P_BODY
Re: Why does my car stumble in the air? - 08/31/09 01:55 AM
Shawn, you might want to try larger needle and seats
on the carbs(might need to go to the alky seats for
more flow
Posted By: 572_dup2
Re: Why does my car stumble in the air? - 08/31/09 01:58 AM
Quote:
Shawn, you might want to try larger needle and seats
on the carbs(might need to go to the alky seats for
more flow
Great idea!! Never thought of that. Im calling holley tech tomorrow an i will ask that question also.
Posted By: boatracer572
Re: Why does my car stumble in the air? *DELETED* *DELETED* - 08/31/09 01:58 AM
Post deleted by boatracer572
Posted By: 572_dup2
Re: Why does my car stumble in the air? - 08/31/09 02:00 AM
Thanks Boatracer572!
Posted By: TheBlackCar
Re: Why does my car stumble in the air? - 08/31/09 03:46 AM
Angled floats. Put a bolt w/ jam nut in each carb so motor doesn't pull scoop down.
Good Luck
Posted By: TheBlackCar
Re: Why does my car stumble in the air? - 08/31/09 03:50 AM
Quote:
The first thing I would do is make a pass with the hood off..
Chris..
Taking the hood off of something fast usually has a negative affect because fuel is pulled out of carb and ends up on the windshield. Not to mention what it does to the air...
Posted By: gregsdart
Re: Why does my car stumble in the air? - 08/31/09 11:31 AM
Quote:
jet extentions wont help with sideways carbs.
They will if they are made to draw from further back in the bowl, and that was my idea, and I believe Als as well. It would take some custom work, as they would need to be flattened a little to allow for ending in the middle of the bowl instead of straight out from the jet. A little tubing, a torch, a (small!)hammer, and problem solved.
Posted By: Al_Alguire
Re: Why does my car stumble in the air? - 08/31/09 02:10 PM
Quote:
Quote:
jet extentions wont help with sideways carbs.
They will if they are made to draw from further back in the bowl, and that was my idea, and I believe Als as well. It would take some custom work, as they would need to be flattened a little to allow for ending in the middle of the bowl instead of straight out from the jet. A little tubing, a torch, a (small!)hammer, and problem solved.
Posted By: Anonymous
Post deleted by Defbob - 08/31/09 03:23 PM
Posted By: gregsdart
Re: Why does my car stumble in the air? - 08/31/09 03:33 PM
Quote:
is it even possible to uncover a jet on side mounted carbs ? maybe nearly straight up if at all
From the looks of your avitar, I would say YES! 
Posted By: Anonymous
Post deleted by Defbob - 08/31/09 05:09 PM
Posted By: DJVCuda
Re: Why does my car stumble in the air? - 08/31/09 05:14 PM
i saw that ( fred ) from the stands - he never had any hesitation, from his foot or the carbs - he dragged the bumper a couple hundred feet - and its safe to say the OP cant uncover the jets -
Posted By: Anonymous
Post deleted by Defbob - 08/31/09 05:24 PM
Posted By: Irun5snd8th
Re: Why does my car stumble in the air? - 08/31/09 06:36 PM
Take this from someone who had the exact same issue. Make sure your fuel pressure from the back to the front is over 25 lbs. It cured mine instantly. Goes up and cuts out in the air. Went to the pump in the back and raised it to 28lbs. The regulator in the front was at 8.5 and I didn't change it but changed the one in the back. Problem solved. Hope it works for you.
Posted By: MR_P_BODY
Re: Why does my car stumble in the air? - 08/31/09 07:19 PM
I would think the front jets(front now) could uncover
and its easier to suck air than it is fuel.... but
then again it could be a air issue going into the
carbs..... or just lack of fuel