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post #1 of (permalink) Old 12-07-2001, 04:28 PM Thread Starter
 
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Holley Carb problems

I've had carb problems for a while..then I thought I fixed them(sorta did) by putting in new gaskets for the idle adjust screws(they were sliding out!)
I haven't driven the jeep in a while and forgot about how horrible it runs.
It takes about 5-10 minutes of straight driving to warm up and clear up most of the bad problems.I usually let it warm up on its own for a few minutes before attempting to drive.
I've changed the filter and sprayed the jets down with carb cleaner.I've ran fuel from a few places also and the problem persist.
It has a 4.3L with a 4 barrel holley.
Thats the background,here is the problem.
As stated above I have problems warming up.
The choke operates perfectly..
but when I do start it up the idle is VERY high when choked.
If I unchoke it, it dies...which is expected.
Right when I put it in gear it dies,unless I have my foot on the gas.
After a few minutes of warming up in my driveway though..it will idle fine(though the idle is way to high)
I can drive down the street and if I let off the gas and slow down too much it will die.(choked or unchoked)
It seems to prefer running choked at stop and unchoked when driving.After a few minutes of driving it will no drive well at all choked..even with holding down the gas.
Its very very slow at acceleration too.
It takes a minute for the engine to react to the gas pedal.
It seems like it could possibly be leaking gas out of the rod that opens the butterflys..would this cause the problem?Is there any way to remedy that?

Thanks
Joey


78 CJ7
Spring over 33's
4.3L V6, TH350
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post #2 of (permalink) Old 12-07-2001, 04:49 PM Thread Starter
 
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Re: Holley Carb problems

oh and fyi leve I did read that holley tuning page you sent me and still couldn't get it to work right

78 CJ7
Spring over 33's
4.3L V6, TH350
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post #3 of (permalink) Old 12-07-2001, 05:14 PM
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Re: Holley Carb problems

How old is that carb ? The last time I saw you post I think I mentioned that I had a similar problem and it was the accelerator pump in the carb . When it stalls ( when you let your foot off the pedal) is it flooding out or because of a lack of fuel ?
Are the vacuum readings within spec on your engine ?
Have you tested the fuel pump pressure ?
It almost sounds like you may have a big vacuum leak somewhere.

Jeff



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post #4 of (permalink) Old 12-07-2001, 09:54 PM Thread Starter
 
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Re: Holley Carb problems

i forgot about the checking for vacuum pressure.
I have looked everywhere for leaks.
I got it to run alright earlier.
Everytime I slow down I must choke it and everytime I accelerate it I must open the choke.
I'll try to check vacuum pressure tomorrow.
How does one do it?

78 CJ7
Spring over 33's
4.3L V6, TH350
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post #5 of (permalink) Old 12-07-2001, 11:43 PM
 
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Re: Holley Carb problems

He has at least two problems,
Hesitation off the line, Accelerator Pump
Choking and not being able to idle correctly, Power Valve or Emulsion tubes full of crap.
The needle and seats may be leaking also...

So many cats, so few recipes...
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post #6 of (permalink) Old 12-08-2001, 02:16 AM Thread Starter
 
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Re: Holley Carb problems

how do I fix that teamrush?
Will buying a rebuild kit fix it?

78 CJ7
Spring over 33's
4.3L V6, TH350
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post #7 of (permalink) Old 12-08-2001, 07:38 AM
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Re: Holley Carb problems

joey
maybe a NEW carb is in the order? man i bet it would run sweet with a new one. hard to say how hacked up this one is from the previous owner. all it takes is $$$$$$$$


post #8 of (permalink) Old 12-08-2001, 10:00 AM
 
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Re: Holley Carb problems

Look for the List number on the front of the air horn... (Air Horn, the thing that sticks up that has the choke blade in it, See attachment.)

I need that list number or a picture of the carb (or both) to know what we are dealing with...

I can only upload one picture at a time, so over the next few posts I'm going to try to teach you how to tune a Holley...
(I'm going to save this stuff for the new web site too!)



So many cats, so few recipes...
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File Type: jpg 9-617607-MainMetering1.jpg (89.5 KB, 6 views)
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post #9 of (permalink) Old 12-08-2001, 10:26 AM
 
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Re: Holley Carb problems

After you find the List Number...

1. Make sure you are getting full throttle travel.
Have someone set in the vehicle and work the throttle pedal a couple of times...
You are looking for:
A. The throttle blades to open and close fully.
Closed means having the linkage resting on the idle speed stop screw.
Fully open means having the primary throttle blades perfectly perpendicular (up and down in the Venturi bore).
If they don't open fully, or they go over center, you have just wasted my time and yours.
Find a spot on the linkage that pulls the throttle shaft(s) fully open. If you have to drill a new hole, do it.

B. You want to be looking for a steady stream of fuel squirting out of the 'Shooters' (correct term, Accelerator Pump Fuel Discharge Nozzles) while the throttle is going down.
This stream should last the entire stroke of the throttle, and sometimes for a tiny bit after the throttle is fully open.
If you get sputtering, air bubbles, starting late, finishing early or anything else than a long, smooth 'squirt', you have an accelerator pump problem.



Techno Babble, but maybe this will help you...
CARBURETOR ACCELERATOR PUMP SYSTEM

The accelerator pump system consists of three main components:
1. the pump diaphragm,
2. the pump cam
3. the pump nozzle.

This is the carburetor system that is most responsible for having good, crisp, off-idle throttle response.
Its purpose is to inject a certain amount of fuel down the throttle bores
when the throttle is opened. By accomplishing this purpose it acts to
smooth the transition between the idle and main circuits so that no stumble, hesitation or sluggishness will be evident during this transition phase.

The first adjustment to check is the clearance between the pump operating lever and the pump diaphragm cover's arm, at wide open throttle.
This clearance should be around .015".
The purpose for this clearance is to assure that the pump diaphragm is never stretched to its maximum limit at wide open throttle.
This will cause premature pump failure.
Once this clearance has been set take a good look at the pump linkage and work the throttle. Make sure that the accelerator pump arm is being activated the moment that the throttle begins to move. This will assure that pump response will be instantaneous to the movement of the throttle.
These adjustments can be made by turning the accelerator pump adjusting screw that is located on the accelerator pump arm together with the pump override spring and lock nut.

The amount of fuel that can be delivered by one accelerator pump stroke
is determined by the pump's capacity and the profile of the pump cam.
The period of time that it will take for this pre-determined amount of
fuel to be delivered is affected by the pump nozzle size.

A larger pump nozzle will allow this fuel to be delivered much sooner
than a smaller pump nozzle. If you need more pump shot sooner, then
a larger pump nozzle size is required. During acceleration tests, if you
notice that the car first hesitates and then picks up, it's a sure bet that the pump nozzle size should be increased.
A backfire (lean condition) on acceleration also calls for a step up in pump nozzle size.
Conversely, if off-idle acceleration does not feel crisp or clean, then the pump nozzle size may already be too large. In this case a smaller
size is required.

Holley accelerator pump nozzles are stamped with a number which
indicates the drilled pump hole size. For example, a pump nozzle
stamped "35" is drilled .035".
Pump nozzle sizes are available from .025" to .052".
Please note that whenever a .040" or larger accelerator pump nozzle is installed the "hollow" pump nozzle screw, P/N 26-12, should also be used.
This screw will allow more fuel to flow to the pump nozzle, assuring that the pump nozzle itself will be the limiting restriction in the accelerator pump fuel supply system.

NOTE: When changing the pump nozzle it's best to jump three sizes. For
example if there's currently a off-line hesitation with #28 (.028")
pump nozzle, try a #31(.031") pump nozzle. If you must use a #37 (.037")
or larger pump nozzle, then also use a 50cc pump.

The same applies to the accelerator pump cams. Once a pump nozzle size
selection has been made the accelerator pump system can be further
tailored with the pump cam. Holley offers an assortment of different
pump cams, each with uniquely different lift and duration profiles,
that are available under Holley P/N 20-12. Switching cams will directly
affect the movement of the accelerator pump lever and, subsequently,
the amount of fuel available at the pump nozzle. Lay out the pump cams
side by side and note the profile differences. This little exercise may
help to better explain the differences between the cams and their
effect on pump action.

Installing a pump cam is straighfforward. It's a simple matter of
loosening one screw, placing the new pump cam next to the throttle
lever and tightening it up. There are two and sometimes three holes
in each pump cam, numbered 1, 2 and 3. Placing the screw in position
#1 activates the accelerator pump a little early, allowing full use
of the pump's capacity. Generally, vehicles which normally run at
lower idle speeds (600 or 700 RPM) find this position more useful
because they can have a good pump shot available coming right off
this relatively low idle. Positions #2 and #3 delay the pump action,
relatively speaking. These two cam positions are good for engines
that idle around 1000 RPM and above. Repositioning the cam in this
way makes allowance for the extra throttle rotation required to
maintain the relatively higher idle setting. Pump arm adjustment and
clearance should be checked and verified each and every time the
pump cam and/or pump cam position is changed:

Lastly, a 50cc accelerator pump conversion kit is available under
Holley P/N 20-11 when maximum pump capacity is desired.


So many cats, so few recipes...
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post #10 of (permalink) Old 12-08-2001, 10:58 AM
 
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Re: Holley Carb problems

The single most frequent screw up is the float level adjustment.
Most people just don't understand how Holley float level is adjusted, so they screw it up badly...

There are three types of Holley float bowls, but we are only going to cover the most common two,
Side float pivot, with the needle and seat on the side of the float bowl....
And Center pivot, with the needle and seat in the center of the float bowl.

Side pivot first...
IF you DON'T have two external fuel lines going into the front and back float bowls, you probably have the side pivot float bowls.
If yo DON'T have a Screw and Nut arrangement in the top center of the very front edge of the float bowl, you probably have a side pivot float bowl.

See graphic for the side pivot float bowl.


Now, you have a brass 'Screw' in the side of your float bowl somewhere.
(Usually on the side away from the throttle cable linkage)
You will have to take that screw out while the vehicle is running...

A word of caution here, You WILL have gasoline all over the top of the engine,
You WILL have a potential fire hazard.
You WILL need to do this outside where a fire will not spread to anything else.
You WILL need a fire extinguisher.
You WILL need to make sure your ignition system isn't leaking voltage and sparking.
You WILL need to have rags under the carb to catch leaking fuel from the site plug hole and the needle and seat.
You WILL need to take appropriate steps to avoid a fire and potential damage to you and the vehicle.


Take the sight plug (brass screw in the side of the float bowl) out.
Start the engine.
Adjust the needle and seat until the fuel barely creeps into the threads of the sight plug hole.
If you do heavy off roading, you may want to turn the adjuster nut in (lower the fuel level) one flat on the nut.
( 1 Flat on adjuster nut = appx. 1/32" to 1/16")

Loosen the LOCK SCREW on the needle and seat, and turn the ADJUSTER NUT to adjust the fuel level.
(This is backwards from almost everything else you will encounter.)
Turn the NUT right (Clockwise to LOWER the fuel level).
Turn the NUT left (Counter- Clockwise to RAISE the fuel level).

When you have the correct adjustment, hold the NUT in place while you tighten the SCREW down.
Replace the sight plug in the side of the fuel bowl.

Repeat with the back bowl if you have a 4 barrel carb.

Clean up the spilled gasoline.
Have a beer, you have just taken care of the #1 problem with most Holley carbs...
------------------

Just as a side note, these side pivot float bowls with round floats are the thing to have for low speed, off camber operation.
The long rectangular floats on the center pivot bowls have a tendency to open the needle and seat when the fuel climbs the side of the bowl in off camber situations.
Using the spring loaded 'Off-Road' needle and seat will help quite a bit also, as will lowering the fuel level one or two flats on the adjustor nut.
(Never more than two flats or you run the risk of uncovering the primary metering jets and leaning the vehicle out)

So many cats, so few recipes...
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File Type: gif 9-617645-FuelInlet,Side.gif (40.2 KB, 5 views)
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