Holley/Demon Carb stumble

-
As far as the starting line experimenting.
I have learned that 2200 stall take all the stretch out of the suspension with this new converter and causes traction problem when the bite goes away.
I have a light on my dash, that comes on when i'm at my starting line stall rpm. It has been turned down to 1600 rpm and seam to work well. It launches just as well at a idle(when its not bogging) but my Reaction time REALLY goes in the toilet!
To be honest, i have never tried to roll the throttle to the floor, will have to give that a try.

Traction is at the bottom of my list at this point. But was at the top of my list,after i installed my new converter last year.
When its bogging it don't seam to give two ***** what i stall it at. It just fall on its face.
 
Cudafever said:
ARE YOU KIDDING ME!!
I can't get one carb to work right and you want me to put two carbs one:realcrazy::p
Click to expand...


LOL. I know it's counterintuitive, but once you get two carbs dialed in, the TR is much less sensitive to weather changes and such.

You have doubled the jet area, bleed area, emulsion and all that. Once you get that sorted out, it takes a much bigger swing to change the tune up.


Hence, that's why Greg Anderson and Warren Johnson have both said they don't change a jet from Denver to Seattle.

Tunnel Rams rule. I'd be using mine if I didn't want the hassle with the hood.
 
So yesterday i went out and warmed up my car set my fuel levels at exactly center of the sight glass, got it good and warm and tested throttle response in neutral and in gear, not stumble
took it out on the road and no stumble at all.........Yup middle of 3 gear she starts poping and banging.
I know that if i raise my secondary bowl up to 3/4 site glass it will bog and not pop again.

Frustrating, but something has been digging at me and i need you guys opinion.
May be grasping at straws...but.....

So you know that little spring behind them center hung floats.
My front float spring really don't do much except just before it hits the bottom of the bowl. On the secondary side it has tension on it all the time. Not so much as to hold the float off the floor or any thing like that but. but if you lay the fuel bowl on its back, so you can see straight down into the bowl. the spring will close the needle. on the front it won't.

Which set up is wrong..........OR does it even matter. like i said the weight of the float will overcome the spring and set in the bottom of the float bowl. there is just a lot more tension on the back bowl spring.
 
Frankly, if it pulls the upper rpm fine through 1st and 2nd, and lays down in 3rd...... sounds like fuel delivery.

Have you done a proper flow test?

Imo, this is the only kind of test worth doing:
Disconnect the line from the carb, and install/adapt a small ball valve onto the end of the line.
With the pump on and fuel flowing into a container, adjust the valve so the pressure gauge reads 6psi.
Do not move the handle on the valve....... shut pump off.
Using a pretty accurate 1 gallon container, with a helper........ have them turn on the pump, and with the gauge still reading 6psi, time how long it takes to fill the can.
For a 500hp motor it should take less than 85 seconds.
550hp - 78 seconds
600hp - 72 seconds

I’ve seen it numerous times where a fuel system would pass the old BG free flow/timed test and totally fail the flow@pressure test.
 
My regulator is set a 9 psi and has a return system back to the tank.
So i could just remove one of the line off of the carb and turn my pump on Right?

Finding me, and making marks on a container might be the problem.
Will have to go out into the garage and find something.
haven't tested my fuel system sence i installed it 3 year ago........It's time to put a check mark on that.

What do you think about the float spring?
 
((I did not read the first 17 pages, so take this as you may))

9psi is a lot, I would back that off to 5-7psi to prevent pushing past the needle valve.

Spring on float...make sure the float moves freely up and down with no hangups. I had a down track issue about 6-7 years ago that was nothing more than my rear float sticking, the needle not shutting and flooding the crap out of my carb (fuel coming out the vent tubes).
 
So i could just remove one of the line off of the carb and turn my pump on Right?
Click to expand...

Without a way to restrict the flow coming out of the hose, the system pressure will be zero if you just dump the end of the hose into a container.

What it flows at zero pressure is of zero importance.

What you need to know is what it flows while maintaining the correct system pressure..... which is where the ball valve comes in.
 
I have not had any problems with fuel flooding. have ran 9 psi for years. I don't want to add any more variables to my problem so it's saying at 9 for now. If my fuel flow test don't pass at 9 i may turn it back down to 6 for that test.
Both floats move free with no binding anywheres.
 
So i have my 6 gal race jug that it marked off in one gal
Maybe run two gal instead of 1 for more accuracy?
Good thought on the ball valve!!!
looks like i need to go to the store to pick up some testing parts.
 
You can leave the regulator at 9psi for the test.
How far open the ball valve is will determine what the system pressure is.

For the test, I would adjust the ball valve so the gauge reads 6psi.

If you want, you can do the test for both 6 and 9 psi....... it’s just a matter of closing the ball valve a bit farther to maintain the 9psi system pressure.
Be interesting to see how much lower the flow is at 9 vs 6 psi.
 
Those float springs don't have that much force. Float should be fully open when bowl is upright, and when flip them over for setting dry, should be shut.

The lower the pressure setting, the less turbulence and aeration, assuming the inlet valves are seeing regulation pressure down the track. 'lectric pump should be pretty consistant delivery regardless of rpm.
 
So i have my 6 gal race jug that it marked off in one gal
Click to expand...

Imo, that wouldn’t be close enough if the test showed your system was barely adequate.
If you end up with like 10 seconds to spare...... then it’s close enough.
 
With regards to operating pressure.

One potential problem running “higher” pressures is if the system is unable to maintain the set pressure for the entire pass.
If the pressure steadily drops throughout the run, so does the float level.

So, if you set the pressure at 9psi, you have to have enough fuel pump/system to be able to maintain it.
If you can only maintain say, 6psi at the top end...... you’d be better off setting the pressure at 5psi, so it would be the same for the whole pass.
 
So now it doesnt sound like a bog but a fuel delivery problem? Prh is right but also could be jetting .
the holleys with the big sight glass gives a goofy read,better to set off the carb, inverted .Also dont go by street launch compared to track . Track might still bog
 
Well.....That was a vary interesting test.
Put two ball valves in so i could use one to set the pressure and the other to block flow while i changed containers

So set pressure at 6 psi with top valve, closed bottom valve put in to my 6 gal plastic race gas can.
Opened valve and started the timer. I was using my smartphone that had a lap counter so i ran 4 gal into the tank hitting the lap counter each gal of gas.
54,52,54 and 51 seconds. So that's real good!!!!!! poured it back into my car and did my 2nt test.

Well if you adj the ball valve to 9 psi.....you get no fuel, because the regulator is sending it all back to the tank.
so i adj the ball valve to 8 Psi and did a one gal test.

1 minute and 55 seconds. Regulator was slipping some gas back into the return so no apples to apples comparison there.
still I'm putting a check mark in that column!!!
 
joec said:
So now it doesnt sound like a bog but a fuel delivery problem? Prh is right but also could be jetting .
the holleys with the big sight glass gives a goofy read,better to set off the carb, inverted .Also don't go by street launch compared to track . Track might still bog
Click to expand...
LOL. Street launches require me to leave in 2nt gear to keep from spinning all the way thru first gear.

NO the bog is still the issue but when i get it to not bog then it lean pops on the top end.
Really beginning to believe it's not a lean bog as it is a flooding bog. still guessing here but i believe it is.
Got to get some exh length after the o2 sensor so i can read more than just wide open throttle.
 
I wonder how much pressure your system will maintain, and still be quicker than 85 seconds.

To test at 9psi, turn the regulator up to about 11 or more, then you can see if it’s still better than 85 seconds with the valve adjusted to 9psi.

As long as it’s better than about 85 seconds per gallon, you’d be pretty sure the pressure(9lbs) is being maintained for the full pass.

You’re running jet extensions and a notched rear float right?
 
1 minute and 55 seconds. Regulator was slipping some gas back into the return so no apples to apples comparison there.
still I'm putting a check mark in that column!!!
Click to expand...

I missed this on the first read.
Why are you putting a check mark in that column?
It’s a fail.

Is shows your system pressure would fall from the pre-set 9psi, which means the floats drop as well.

The system pressure should set to a number 1/2 to 1 psi lower than what the system can maintain for your power level(unless it will maintain more than enough pressure, then set it to where you want).

You should see what pressure your system can maintain while being able to pump a gallon in just under 85 seconds, and set the regulator just below that number.

115 seconds for one gallon, at 8psi....... means your system will support about 375hp, and not lose pressure.

If you’re only making 375hp, it’s fine..... but at 500hp, the floats are dropping.

Unless!!!!!
If you do the test with the regulator set for higher pressure(11-12ish), and the 9psi test is better than 85 seconds....... then I’d say leaving the regulator at 9psi would be okay.

Re-read it again...... did you mean one gallon in 115 seconds....... or first gallon 60 seconds, 2nd gallon 55 seconds?
If the latter...... disregard this post...... and keep the check mark ;)
 
Last edited:
Yup at 6 psi first gal 55 sec 2nt gal 52 sec later 3d gal, another 55 sec later and the final gal took 51 sec.
Average =52.75 Seconds per gal

Yes i would have to raise the psi on the regulator to get a apples to apples comparison between 6 and 9 psi flow.

This is the pump i'm running.
Walbro High-Pressure Inline Fuel Pumps GSL392BX
 
Last edited:
Actually, I was referring to the “1 minute and 55 seconds” you stated for the 8psi test.

115 seconds per gallon?
or 1st gallon 60 seconds, 2nd gallon 55 seconds?
 
The 8 psi was 1 minute and 55 seconds

Edit: per A Gal
I would have to raise the regulator pressure to get a acurite reading. reg is dumping fuel because it's getting close to the regulated 9 psi
 
PRH said:
I missed this on the first read.
Why are you putting a check mark in that column?
It’s a fail.

Is shows your system pressure would fall from the pre-set 9psi, which means the floats drop as well.

The system pressure should set to a number 1/2 to 1 psi lower than what the system can maintain for your power level(unless it will maintain more than enough pressure, then set it to where you want).

You should see what pressure your system can maintain while being able to pump a gallon in just under 85 seconds, and set the regulator just below that number.

115 seconds for one gallon, at 8psi....... means your system will support about 375hp, and not lose pressure.

If you’re only making 375hp, it’s fine..... but at 500hp, the floats are dropping.

Unless!!!!!
If you do the test with the regulator set for higher pressure(11-12ish), and the 9psi test is better than 85 seconds....... then I’d say leaving the regulator at 9psi would be okay.

Re-read it again...... did you mean one gallon in 115 seconds....... or first gallon 60 seconds, 2nd gallon 55 seconds?
If the latter...... disregard this post...... and keep the check mark ;)
Click to expand...

Without a return to tank regulator the system pressure would be 87 Psi
 
You must log in or register to reply here.
-

Back
Top