Holley 6919 carb.

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Fredensborg

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7173 Mustang Supporter Member
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1973 Mach 1
1980 Bronco
A couple modern Fords
Ok guys, so I (with the help I a more knowledgeable friend) solved my spark issue and actually had my mustang running for the first time in over a year today! Long story short, the coil wasn't grounding properly which was causing me to lose spark. However, I now have a carb issue and would love to hear your thoughts. It is a Holley carb list number 6919 which I think (according to the Internet) is a "4160 600cfm" carb. (Don't really know what that means) I did a rebuild kit on this carb awhile ago and thought I did everything right but I must have screwed something up. Things run fine when you are giving it some gas but, when I try to turn the idle down to a normal rpm it dies everytime. And my friend showed me with a flashlight that fuel seems to be pouring into the secondaries. He told me that when you look in the carb while its running the gas should look like a fine mist or vapor going into the motor, the gas in mine looked more like big ass droplets spraying in. He thought that maybe something could be clogging up the needle and seats and that I should take it apart and look everything over. I had a few leftover parts in the rebuild kit when I was done, is that normal? Some of the parts included in my rebuild kit didn't even look like they belonged anywhere in my carb. So I obviously didn't put them in. I have never done a carb rebuild kit before, but I took my time and took a lot of pictures and I am fairly confident that I put it all back together correctly.

 
Ok, here's a video of my carb dumping gas in the motor, does it look like its dumping gas appropriately? my friend says this is way to much gas going in and it should be like a fine mist or vapor going down the intake.

oh, and this is the primaries, not secondaries. I cant keep the car running under about 2500 rpm.





and yes I have a terrible sounding exhaust leak!

 
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To start, I would check the primary side float height and like your friend said the needle and seat. How long since the carb has been gone through? You should not have any fuel flow from the main nozzles at idle, all fuel should be coming through the idle/transition circuit. What main jets are in the primary side of the carburetor? I'd try starting with 68 +/- 1 jet size to get going and an 6.5 power valve. The idea behind going with a 6.5 power valve is to reduce the chance it opens before WOT (the PV flows additional fuel for power when the vacuum drops below the value).

I just noticed something curious, is there any fuel coming from the accelerator pump? If not check the gasket between the carb body and the metering block. Take photos of your components and gasket placement as the carb comes apart. Can you post an overall view of the carb?

If it has been a while since the carb has been rebuilt it may be a good time to go through it again. Be sure to clean out each passage using no more pressure than you get from an aerosol can. Air pressure from a blow gun can jam debris into small passageways. I use tag wire to make sure all the passages are clean.

That has to make your eyes water in the garage.

 
I just rebuilt it last year, but it was my first time and its possible I messed something up.

When you saw fuel squirting it was because I was hitting the throttle linkage by hand. Or do you mean that there should be no visible fuel at idle at all?

How do I tell what size jets I have? Is it stamped on them somewhere?

And yes, my eyes were watering like I was in a onion chopping factory.

Here's a couple overall pics.....I'm bout to pull it in a few mins


And one more


Here's a pic I the metering block gasket, don't know what that white residue is in there. Maybe it didn't get clean enough last time?

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I just rebuilt it last year, but it was my first time and its possible I messed something up.

When you saw fuel squirting it was because I was hitting the throttle linkage by hand. Or do you mean that there should be no visible fuel at idle at all?

How do I tell what size jets I have? Is it stamped on them somewhere?

And yes, my eyes were watering like I was in a onion chopping factory.

Here's a couple overall pics.....I'm bout to pull it in a few mins

And one more

Here's a pic I the metering block gasket, don't know what that white residue is in there. Maybe it didn't get clean enough last time?
Did it run after the rebuild? Is this a new development?

You should not have fuel flowing from the main nozzles at idle. During idle fuel and air are introduced below the throttle plates. There is a small hole for idle and a fine slot for transition. As you work the throttle you should have fuel coming from the accelerator pump squirter.

The jets are stamped for size. The number is a flow rate not a specific size. BTW drilling a jet will ruin it.

The white residue looks like it may be some corrosion. Today's fuel with ehthanol leads to that sort of thing in carburetors.

I figured with all that fuel flowing the air quality in your garage had to be suspect. :D

 
Did it run after the rebuild? Is this a new development?

You should not have fuel flowing from the main nozzles at idle. During idle fuel and air are introduced below the throttle plates. There is a small hole for idle and a fine slot for transition. As you work the throttle you should have fuel coming from the accelerator pump squirter.

The jets are stamped for size. The number is a flow rate not a specific size. BTW drilling a jet will ruin it.

The white residue looks like it may be some corrosion. Today's fuel with ehthanol leads to that sort of thing in carburetors.

I figured with all that fuel flowing the air quality in your garage had to be suspect. :D
Yup it ran after the rebuild, for awhile....I was adjusting the carb after the rebuild and during that process it died a few times. Finnally it died for good and I couldn't get her back (because of my spark issue that is now solved).

I think that white stuff is from the "purple power" solution I soaked everything in the first time, it's all over the outside of the carb too. I took it apart today and hit all the holes and passages in the metering block with some carb cleaner, I'm pretty sure that is clean now (I'm definitely getting more confident tearing into the carb now that I have done it 4 or 5 times!):D

If the jets are the two screw in things below and on either side of the power valve in the metering block, then they are stamped with a "70H" don't know what that means either......:shrug2: oh and the power valve isstamped with a 6 and a 5 :shrug:

Not sure which one is the accelerator pump squirter either, The only squirter I see is the one that squirts on the primary "barrels"? But I did notice that the adjustment screw on the throttle linkage that operates the accelerator pump was pushing down on the pumpers lever, so I backed it off so it is just barely touching it.....but it didn't help anything.

Heres one more video that illustrates the problem, you can still see that gas pissing in the carb and the motor stalling out around 2500-2000rpm.




 
The purple power is a little harsh for aluminum or zinc. Be sure to wash the carb and parts with soap and water to neutralize the cleaner. I like simple green in a 50/50 mix. Wipe down the exterior surfaces with WD40 or similar. That should keep the external corrosion down.

It never hurts to have practice with whatever you are doing.

The jets do screw in and have a pocket in the face and a hole that runs through. They are in the lower part of the fuel bowl side of the metering block. A 70 jet is probably a little big but should not cause the condition in your videos. The 6 and 5 on the powervalve means the valve opens when the vacuum drops to 6.5 inches. The lever for the accelerator pump should sit on the cam with no clearance when the throttle is closed, when the throttle is wide open there should be a little room for the lever to move more. The accelerator pump squirter is in between the primary bores and have a port that discharges fuel into each of the primaries.

How did you set your float? Typically if a needle is stuck open fuel will flow from the vent tubes.

I would proceed by making sure all passageways are clean and clear. Use some thin soft wire like tag wire to clean any crud from the passageways.Clean all fuel and air passages, air bleeds, etc.

 
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How did you set your float? Typically if a needle is stuck open fuel will flow from the vent tubes.
I think you are right, I did some Googleing and it sounds like when other people out there are having fuel drip out of the primary boosters at idle (I'm getting this carb lingo down pat!) 90% of the time it is caused by too high of a fuel level in the bowl. But, I trashed my needle and seat gaskets when I was looking at it yesterday, so I will have to make some out of the leftover gasket material from my rebuild kit....hopefully I'll have this problem solved later today!

 
Well, I just got done making sure the floats are set at the correct level (just below the viewing hole) and it is still pissing gas out of the primary boosters!!! I'm about ready to throw this POS into the trash and order a new one, but #1 don't have the cash, and #2 it's still probably something stupid that I haven't figured out yet.......:shrug2:.......and I just realized I probably posted this thread in the wrong area, should have been in the tech forum! oops!

 
This is a fine place to post.

Can you post photos of the carb components? If it's something that is visible in photos maybe someone here will see it.

I'm thinking the caustic nature of the purple power may have damaged the carb components.

 
I have been working with Holley's for 40+ years. I suspect one or more of the following four things that is causing your problem.

1. Power valve diaphragm ruptured - very common and I would check this first

2. Power valve has wrong gasket - two different styles

3. air bleeds plugged or not working - check to see if you used the right gasket on the metering block.

4. fuel level too high - would have to grossly off a lot to cause this problem

Check the Power valve first - I would bet on it over the others.

 
X2 on Edself's post.

Especially if you had an ignition problem, a single backfire (common with erratic firing cylinders) could rupture the power valve.

Replace it and the gasket, regardless of anything else.

Also a note of interest is all of the black soot in the 4 venturis... they should never be that way. Looks like the engine has been gagging on a rich condition for a long time.

 
I have been working with Holley's for 40+ years. I suspect one or more of the following four things that is causing your problem.

1. Power valve diaphragm ruptured - very common and I would check this first

2. Power valve has wrong gasket - two different styles

3. air bleeds plugged or not working - check to see if you used the right gasket on the metering block.

4. fuel level too high - would have to grossly off a lot to cause this problem

Check the Power valve first - I would bet on it over the others.
Thanks for the suggestions...I'm about to tear back into this project, I'm going to give this carb buisiness one more shot before I take it someplace. I'll check that powervalve first, is there any visual indication that it is shot? Or just get a new one no matter what it looks like?



X2 on Edself's post.

Especially if you had an ignition problem, a single backfire (common with erratic firing cylinders) could rupture the power valve.

Replace it and the gasket, regardless of anything else.

Also a note of interest is all of the black soot in the 4 venturis... they should never be that way. Looks like the engine has been gagging on a rich condition for a long time.
It probably has, I have owned this car for over 10 years and haven't done anything to it performance-wise. I bet I havent even put 3000 miles on it yet. I'm gonna start investigating this problem again soon, and if I cant figure it out I'm going to bite the bullet and take it to a shop and have them fix it up. Mustangs arent ment to live in garages!! :D Anyone know of a good shop in central Minnesota?

 
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There's no real good way to check the powervalve. They are not very expensive, replacement is cheap insurance. After sitting for almost 2 years it's possible the gaskets are dried out and will need to be replaced.

Best wishes on the project!

 
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