Wheel stand--carb stumbles

[rfoll]

Gauges were a part of daily life in the industry I worked in. Hundreds of pumps, seal water pressure on all of them. Pretty common for the supply water to be turned off and the gauge still read the same. They do not handle pulsations well, it wears out the little gears inside. You should have an isolation valve for your fuel pressure, and only turn it on when you feel the need to monitor or troubleshoot the system. New gauges in the 30 to 100 psi range are commonly off 2-5 psi, or sometimes the error would be off according to the range, increasing or decreasing a percentage in the scale. These were not 5 and 10 dollar pieces of equipment. I had a test manifold with a certified gauge on my work bench to test everyone I installed new, or any that I found suspicious.

[Strange Magic]

Fuel pressure regulator has nothing to do with this.

Chances are based upon your story, that when you changed your regulator, debree got into one of the carbs and it is logged in one of the circuits. Take the carbs apart and clean them well. Use wd 40 to purge through the circuits.

[emleydon]

Joe, If your new regulator has a bigger flow orifice (and a more pliable diaphram) maybe it is seeing more flow on take off due to a fatter pressure/flow curve and sensitivity of the new one during max fuel demand. Don

[grant6395]

needle and seat o rings....replace them.does the new reg have larger orfices?does it flow more fuel?it may be momentarily leaking by the needle and seat orings and briefly flooding the engine slightly...I battled this issue with a new fuel system..carbs(book) were unchanged..nearly gave up the sport...change them.i bet it fixes it..my situation was a 400 ci sbf in my b/a comp car.

[Kevin Johnson]

Gauges were a part of daily life in the industry I worked in. Hundreds of pumps, seal water pressure on all of them. Pretty common for the supply water to be turned off and the gauge still read the same. They do not handle pulsations well, it wears out the little gears inside. You should have an isolation valve for your fuel pressure, and only turn it on when you feel the need to monitor or troubleshoot the system. New gauges in the 30 to 100 psi range are commonly off 2-5 psi, or sometimes the error would be off according to the range, increasing or decreasing a percentage in the scale. These were not 5 and 10 dollar pieces of equipment. I had a test manifold with a certified gauge on my work bench to test everyone I installed new, or any that I found suspicious.

This should be a sticky note somehow.

[donc]

The regulator change stared this problem? Id try moving the mounting position of the regulator, as far forward of carb as possible.Saw a Mopar stocker having same problem,Bill Jenkins walked by car in the lanes looked underhood, told the owner to move the regulator forward,that cured it?

[fdicrasto]

Going back to the fact less fuel in the bowls improves the leave issues, sounds like fuel forced out vents as one possibility which should clear up with the hose,vent modification. The other probable possibility was touched on by Strange. I would have the old regulator apart and check for crud such as fuel cell deterioration can produce and if found, could be a source of trouble with new regulator. Seen a lot of pressure creep with some regulators that lead to needle and seat problems also. Good luck Joe. By the way, having run combo's like yours for over 40 years; Been there,done that!!! Phil D.

[joespanova]

Try the 4224s.......I had these same issues with 4150 based carbs on my t-ram.They worked fine intially then developed a problem with stumble after launch like yours. I tried several remedies...none solved it. I gave up and went to the 4224s and never looked back. Years later I acquired 2 more 4779s and set them up the same way and they did the same thing as the previous 2.
The 4224s are really good carbs.

[BrazilianZ28Camaro]

Joe, what was the car problem with the old regulator?

This may point to a direction to find out your actual problem.

[bigjoe1]

It seems like most of you do not understand what has happened- This is a good running car that we have been running for many years. It runs 8.80 at over 151 MPH . When we discovered that the regulator was not responsive, we tried several things to see if it could be fixed, but to no avail.The old set up ran good for 200 or more runs without any problems.The big unknown is where the actual fuel pressure was all the time when it was running good. The new regulator is the EXACT same one as the original. The new setup is running very close to where it used to run, so it is almost back to where it was.. I do appreciate every ones suggestions so far. The next time out, I am sure we will get it right===

JOE SHERMAN RACING

[The Radius Kid]

A little reading material for tose that are interested:

http://en.wikipedia.org/wiki/Bourdon_tube#Bourdon

http://www.wika.us/upload/Download_TB_P ... _36621.pdf

http://www.chemicalprocessing.com/artic ... e-failure/

[GARY C]

Did it ever work before?
You are obviously uncovering a circuit are shooting fuel out the vent tube.
It could be a bad booster signal, I doubt it would be intake related, I have heard the intake is only there to hold the carb up.

[greywolf]

Fuel pressure regulator has nothing to do with this.

Chances are based upon your story, that when you changed your regulator, debree got into one of the carbs and it is logged in one of the circuits. Take the carbs apart and clean them well. Use wd 40 to purge through the circuits.

Might be on to something here.

[steve cowan]

hey joe, off topic but i dont care- just read your articles on your website about your 615hp 383 sbc and your 800hp 374 ci ford windsor watched youtube footage of the red nova running 5.70s in the 1/8 mile back in 2009,and noticed your name more than once when i read vic edelbrocks biography,you have been making horsepower nearly as long as i have been alive so i say thanks for sharing

[cjperformance]

It seems like most of you do not understand what has happened- This is a good running car that we have been running for many years. It runs 8.80 at over 151 MPH . When we discovered that the regulator was not responsive, we tried several things to see if it could be fixed, but to no avail.The old set up ran good for 200 or more runs without any problems.The big unknown is where the actual fuel pressure was all the time when it was running good. The new regulator is the EXACT same one as the original. The new setup is running very close to where it used to run, so it is almost back to where it was.. I do appreciate every ones suggestions so far. The next time out, I am sure we will get it right===

JOE SHERMAN RACING

Joe- many here drag/race and know, and understand what has happened... A fault has occured and can not be identified. Its happened to us all. We panic, change, guess, swap stuff and lose the path.
In my experience with racing -- log everything, ( even the color of your underpants ) , change one thing at a time and log the difference, prove/retest the change.
So, reset everything to how it was. Even refit the reg to prove the problem if you need to. Then change one thing- ie- set fuel pressure to 5lb if you dont have a reference pressure, Run it again with everything else exactly the same and you will see the problem.