Leaking Holley Carb

[Steve Meltzer]

As this unfolds, I'm liking the idea of a stuck float or needle/seat problem, best. T'ain't the gaskets on the long securing machine screws, nor anything in the back half of the carb. Hope to get out there tomorrow....life keeps getting in the way of getting anything done. Not sure when i had time to do this stuff before I retired, but it seems i have even less now. s

[Lincoln tech]

Needle and seat or float problem would cause the fuel to be pushed out of vent tubes but only with engine running or while cranking .

[shelbydoug]

If there is an electric fuel pump in line and running while engine is not, you can leak out fuel if there is an fuel inlet valve stuck open.

That is unusual since the needle and seat are usually stuck closed due to the engine sitting long enough to dry the fuel out of the bowls. That is in the 3 to 4 week time period.


If there are the original brass floats in the carb, they can be collapsed due to attempting to start the engine with no fuel in the carb. There is usually a backfire involved in that scenario though.

On my carbs I switch to the solid nytrofil floats for that reason alone. I have taken in carbs in trade and when disassembled find often collapsed floats.


You need to open the sight plugs in the carb. This situation is part of why they are there. If fuel drips out, the level is a little high. If it pours out after multiple attempts to start, you probably need to disassemble the carb.

I have found that with the ethanol mix in pump gas that you need to set the fuel level under the site level opening. The primary bowls are not usually an issue but the secondary bowl is more difficult to get right since it normally has a lower site plug location, therefore normally a lower fuel level then the primary bowl and you run the risk of running that bowl dry at high rpm use.

That can be fatal to your engine since it will violently backfire if run dry under WOT. There you can break a piston, in various ways, like putting a hole through one or more commonly breaking the top piston ring land.


You can try just removing the fuel bowls with the carb on the engine but it is just about the same amount of work to remove it and then disassemble it on the bench.


A blown power valve is unpredictable as to how much fuel it will leak. In my experience it doesn't flood the engine out initially and is just enough of a leak to cause complications like an inconsistent idle and running very rich at idle.

When you examine them by sight it isn't always apparent that there is a leak in them. You really need a PV tester to verify that the diaphragm is holding vacuum. The Holley bubble packed valves are the best but due to the unknown storage time they have seen, can be marginally dried out and ready to crack. You NEED to vacuum test each and every one. Just to say it is "new" is not enough.

The best thing to do is just put a new HOLLEY service kit in the carb and use the Holley bench adjustment instructions for setting the float levels on the bench. That procedure in my experience does tend to set the floats a little high. You need to be aware of that. You most likely are going to lower the levels about 1/2 a turn on the adjustment screws.

You actually CAN run with the fuel level high in regards to the sight plug hole BUT on steep inclines you may flood out and stall. Best to get the levels a hair below the sight plug hole. It's the best compromise.


Also these carbs do not like fuel pressure levels much over 5psi, which is what a new mechanical fuel pump will deliver although they will tolerate pressures up to about 7psi.


If you are not confident about doing any of this, then bring it to a shop that rebuilds carbs. Ham handed is not what you want to be with carburetors. They have no patience for your impatience.

[Steve Meltzer]

Haven't touched the $^%$%^* carburetor for 2 days. Went out there this AM, and slowly added 40cc of fuel (yes, exactly with a 20cc syringe!) down the venturi vent tube and it didn't leak, as it had. Fired her up and viola....dry as a bone! I did nothing this AM, except X my fingers...no accounting for good luck. It ended well with me learning so much.....thanx guys A+.

Sometimes chicken, sometimes feathers.
steve

[shelbydoug]

Haven't touched the $^%$%^* carburetor for 2 days. Went out there this AM, and slowly added 40cc of fuel (yes, exactly with a 20cc syringe!) down the venturi vent tube and it didn't leak, as it had. Fired her up and viola....dry as a bone! I did nothing this AM, except X my fingers...no accounting for good luck. It ended well with me learning so much.....thanx guys A+.

Sometimes chicken, sometimes feathers.
steve

You have a magic touch.

[Steve Meltzer]

ShelbyDoug tell my wife that, and maybe I'll get lucky! s

[Lincoln tech]

What a guy , congrats You fixed it , meanwhile keep an eye ( or both eyes  ) on it . And keep it covered and warm just like you have it in the picture  Good luck.

[shelbydoug]

ShelbyDoug tell my wife that, and maybe I'll get lucky! s

I don't know if that is a good idea? She would want to know how I know about your magic touch? Best keep that between us?

[rhjanes]

Check this link.  Component guide from the 428cobrajet web site.

https://www.428cobrajet.org/id-carb-68

[Steve Meltzer]

@Shelbydoug...still laughing at your quip.
@Lincoln tech....it makes me nervous to appear to have solved a problem with no logical and scientific reason to explain it.
@ rhjanes thanx for the link to that great website.

will drive tomorrow...close to home and with fire extinguisher, etc on passenger seat.

steve
"Go 'stros"

[Lincoln tech]

Good luck Steve , keep us updated .

[Drew Pojedinec]

A few things to check.

https://www.facebook.com/AirFuelSParkTech/videos/594345029388709/

But if it is pouring out as fast as you pour it in, sounds more serious.

[Steve Meltzer]

You guessed it...leaked like the proverbial sieve. Took it apart (again) rechecked everything...needle moves freely, and though I didn't check the float the way you should, it feels light. Filled the bowl, as before. Dry. Went to start her....bad starter! No go. Not sure if the starter is original to the car, nor anything about "numbers", but would take suggestions on that, too. arrrggghh! s

[rhjanes]

You guessed it...leaked like the proverbial sieve. Took it apart (again) rechecked everything...needle moves freely, and though I didn't check the float the way you should, it feels light. Filled the bowl, as before. Dry. Went to start her....bad starter! No go. Not sure if the starter is original to the car, nor anything about "numbers", but would take suggestions on that, too. arrrggghh! s

Starters are fairly easy to rebuild.  They used to make a kit for them.  I've not done one in 25+ years....
Here is the component page from 428cobrajet to check your numbers on the starter.  Determine what is there before you decide what to do. 
https://www.428cobrajet.org/id-starter

[Drew Pojedinec]

You guessed it...leaked like the proverbial sieve. Took it apart (again) rechecked everything...needle moves freely, and though I didn't check the float the way you should, it feels light. Filled the bowl, as before. Dry. Went to start her....bad starter! No go. Not sure if the starter is original to the car, nor anything about "numbers", but would take suggestions on that, too. arrrggghh! s

Is the starter bad? Or is a cylinder full of fuel?

Anyway, if you want to slowly go through each thing and test it, I'd be happy to walk you through it. Rather do email, but whatever.