Pressure Regulator

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stumblinhorse

stumblinhorse

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Is there any reason I cannot just pick up a regulator and throw it on the line to see if that helps my carb being too rich? I have a rubber line I can plumb in, temporarily, to bring my pressure down. If is see lower readings on the AFR gauge then I will permanently attached it to the fender well and pick up some hard lines.
 
Is it a carb or EFI?
If carb you can use a regulator, 6 to 7 pounds max for a carb.
 
stumblinhorse said:
Is there any reason I cannot just pick up a regulator and throw it on the line to see if that helps my carb being too rich? I have a rubber line I can plumb in, temporarily, to bring my pressure down. If is see lower readings on the AFR gauge then I will permanently attached it to the fender well and pick up some hard lines.
Click to expand...


Or pressure gauge could be attached directly to the carb feed line to find out what the pressure is.
 
If you need to prove it to yourself that way, go ahead.
Combine or seperately with TrailBeast's suggestion.

Everyone learns differently so do what you need to.

I've driven a couple of times relying on gravity feed - that's easier to rig with single inlet carb

All the carb needs is fuel in the bowl. It's pretty much like a toilet tank. Whether the toilet's tank is filled by a supply line with 100 psi or 20 psi or a bucket doesn't matter much.
The hieght of the fuel in the bowl only slightly effects the delivery to the engine. Air pressure does most of the work. If the pressure is effecting the hieght of fuel in the bowl, adjust the float. This will slightly effect AFR, lower level will be slightly leaner.

A good explanation and illustrations of the carb operations from Chrysler
Carburetion Fundamentals & Facts (Session 273) from the Master Technician's Service Conference
 
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stumblinhorse said:
Is there any reason I cannot just pick up a regulator and throw it on the line to see if that helps my carb being too rich? I have a rubber line I can plumb in, temporarily, to bring my pressure down. If is see lower readings on the AFR gauge then I will permanently attached it to the fender well and pick up some hard lines.
Click to expand...


No reason at all. What is your current fuel pressure? How do you have your floats set? How much of your idle fuel transfer slot is exposed? What is your cruise A/F ratio now?

What's your initial and total timing set at now? Do you have any vacuum leaks? How did you test that?
 
Mattax said:
All the carb needs is fuel in the bowl. It's pretty much like a toilet tank. Whether the toilet's tank is filled by a supply line with 100 psi or 20 psi or a bucket doesn't matter much.
Click to expand...
well, that is not true
the carb is set up to withstand a certain inlet PSI, most times 8 PSI
the float can only withstand 8 PSI to close the inlet of fuel
if his line pressure is higher then that, the float, when rising to the top, will not be able to close the intake, and the bowls will flood
then fuel will drizzle into the throat of the carb and the car will run like crap

to stay with your toilet bowl analogy, your tank would overflow and water would pour all over your bathroom floor, next thing you know, the wife walks in, slips and falls, knocks her head on the toilet bowl (chipping it) and you're spending the rest of your life taking care of a woman on a respirator
 
fuel height is more important than may be thought, especially for idle. On a slant is it the first thing you do after a valve adjustment. Reducing the pressure feed to a carb is not going to change AFR unless the fuel is blowing the needle off the seat. Carters like 5, Holleys like 7.
 
diymirage said:
well, that is not true
the carb is set up to withstand a certain inlet PSI, most times 8 PSI
the float can only withstand 8 PSI to close the inlet of fuel
if his line pressure is higher then that, the float, when rising to the top, will not be able to close the intake, and the bowls will flood
then fuel will drizzle into the throat of the carb and the car will run like crap

to stay with your toilet bowl analogy, your tank would overflow and water would pour all over your bathroom floor, next thing you know, the wife walks in, slips and falls, knocks her head on the toilet bowl (chipping it) and you're spending the rest of your life taking care of a woman on a respirator
Click to expand...
You only read part of it. Use an appropriate valve and your toilet won't overflow whether it has 20 psi on it or 120 psi on it. It will fill more slowly at 20 psi than at 60 psi.

And I disagree on the 8psi. For most carbs we use here, 8 psi is pushing the limit of what the inlet valve can hold off - the bigger ones of course are worse.
 
pishta said:
fuel height is more important than may be thought, especially for idle. On a slant is it the first thing you do after a valve adjustment. Reducing the pressure feed to a carb is not going to change AFR unless the fuel is blowing the needle off the seat. Carters like 5, Holleys like 7.
Click to expand...
Yes and its first thing Holley says to check and adjust when installing one of their aftermarket carbs.

and exactly. The hieght of fuel in the bowl is determined by the float position, pressure only makes a little difference if any (unless the valve can't hold it).
 
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Diymirage, I thought you were going to say a lifetime with a chipped toilet. Just jiggle the handle.
 
Edelbrock 600, I was going to set to something like 4 to start. Street engine, mostly stock.

Need to find a piece of plumbing for the inline gauge. But that is a good idea to start.
 
pishta said:
Diymirage, I thought you were going to say a lifetime with a chipped toilet. Just jiggle the handle.
Click to expand...
Just remove the flapper -stopper at the bottom of the tank and let it run at wide open all the time.
:lol:
 
More information on my set up. New Edelbrock 600 Carb, new Carter M6866 Advertised Max PSI 6.5.
Carb main is .095, Secondary is .089 and metering rod is a .068x.042 This is the leanest setting #27 in the book. IMS are at about 1 turn out. Engine runs fine, plenty of power for a 69 318 with Weiand Stealth, Elect ignition OEM Blue Box, timing is 14* BTDC. Switched to RN14YC plugs yesterday also, Long tube headers, Dual 2.5 exhaust no crossover. AFR in the Odd side collector. My Alternator and VR were dead, so I thought low power to the ignition was causing my problem. I replaced the Alt and VR, took several attempts but finally good Volts at all readings, and still is too rich. I live at 7000 ft and the engine will mostly be at that elevation.

Adjusting the IMS impacts the reading at idle no problem, but as soon as hit the throttle it goes rich and takes a while to return to a reasonable reading. If I set the idle AFR to be about 13-14, runs little rough on the idle. Then I hit the throttle it goes rich and the take about 15-30 seconds to return to 13-14 at idle.

So I am thinking fuel pressure is next to check. Also going smaller jets next.
 
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Mattax said:
Just remove the flapper -stopper at the bottom of the tank and let it run at wide open all the time.
:lol:
Click to expand...
flyingtoilet1.jpg


 
Mattax said:
You only read part of it. Use an appropriate valve and your toilet won't overflow whether it has 20 psi on it or 120 psi on it. It will fill more slowly at 20 psi than at 60 psi.

And I disagree on the 8psi. For most carbs we use here, 8 psi is pushing the limit of what the inlet valve can hold off - the bigger ones of course are worse.
Click to expand...

a toilet might not overflow with the right valve, but over pressurize the inlet on a carb, and like you mentioned, it will (8 PSI might indeed be pushing it)

and i think that is why the OP is thinking of putting in a regulator, because the valve (in this case, the float/needle and seat) can only withstand so much, so that is where our toilet comparison fall apart


@stumblinhorse what is your fuel pump?

and what is your definition of "rich", got a number?
(you should go a little richer at WOT
and...what kind of AFR gauge ?
 
At 7000 feet little O2 means lean the fuel. Carbs leave factory with a base line 70* sea level tune. You can fine tune AFR with float setting.
 
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