Holley Carb Help Needed

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David70FJ40

David70FJ40

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I replaced the carb on my 40 not long ago with a Holley 350 cfm. Really woke up the old F engine. Tried to start it recently and the gas was flowing out of the vent hole. Called Holley and they suggested the needle was in need of replacement.

Not being a carb person I want to know if anyone would be available on Sat to help with the replacement.
 
David70FJ40 said:
I replaced the carb on my 40 not long ago with a Holley 350 cfm. Really woke up the old F engine. Tried to start it recently and the gas was flowing out of the vent hole. Called Holley and they suggested the needle was in need of replacement.

Not being a carb person I want to know if anyone would be available on Sat to help with the replacement.
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Stuck float...possibly? These have the same center pivot in the float bowl as the 750 CFM from the 4150 series. It could also be a needle.

You can always remove one of the site plugs from the fuel bowl to check the fuel level. If the fuel level is too high (fuel flows out as soon as you remove the plug) after the fuel pump has cycled, it could mean that one of the aforementioned parts needs to be replaced. You should be able to pick them both up from just about any auto parts store, but I prefer NAPA.

@David1947 I'd come over and help this weekend, but I've got family in-town. If @GLTHFJ60's father-in-law is around, I'll bet he's forgotten more about Holley carbs than I'll ever know. He's probably the right guy for you. That said, I'm not trying to volunteer @GLTHFJ60 or his father-in-law.
 
Electric fuel pump or factory mechanical pump?

Stuck float is most likely cause.
 
Electric pump. I removed the fuel bowl and the float moved easily. I have the rebuild kit.
 
David70FJ40 said:
Electric pump. I removed the fuel bowl and the float moved easily. I have the rebuild kit.
Click to expand...

I'd check the needle and seat next. Check to see if it's stuck. Hit it with some carb cleaner if the needle doesn't move freely or gets hung up. If that doesn't work, throw in a new one.

Fortunately an electric pump will make it easier to readjust the float level.
 
Needle valve is the issue. Be sure when working on the carb not to turn upside down as needles can be damaged. When reassembling be sure float level is set as accurately as possible using the measure tool in the kit.

BTW ... 350 CFM is big for that motor. It may need some jet work to keep it from running rich.
 
It does run rich.

You have been gone a while Rice. Where ya' been?
 
If I don't swap out the F for a SBC next year I will invest in the Sniper kit. Can't do it now, to many other things in the way. Just spent about $1500 at the HP hospital in July.
 
David70FJ40 said:
Electric pump. I removed the fuel bowl and the float moved easily. I have the rebuild kit.
Click to expand...

You moving the fuel bowl easily does not mean that it will move easily with the fuel level.

Is a return plumbed into the system? The electric fuel pump could easily be overfilling the bowl.
 
Just replaced the inlet needle valve. Adjusted as to the instructions, level in the bowl, reinstalled and has th same problem with gas flowing out of the over flow vent. I then loosened the needle valve lock screw and adjusted it down until the flow stopped the reinstalled the lock. Could it have been the original needle valve, which looked clean and pristine, simply vibrated loose from engine vibrations? The old F started right up and ran like it should. Before the problems started I was seeing a lot of what I though was moisture coming out of the tail pipe and saw none today. Might have been running far to rich before?

Anyway, runs well and sounds like the F sounded before. Maybe I should have gone with the Sniper EFI instead.

@GLTHFJ60 No return line, the fuel pump is set for a Weber at less than 4 psi. I believe I turned it down to 2 psi prior. Need to check.
 
Without a return, if your engine is not running but the fuel pump has power, IIRC it will overflow the bowl and come out the vent tube. Pressure won't affect this problem, other than how fast fuel flows out of the tube. If the fuel pump is running and the engine isn't consuming fuel, it will overflow.
 
I am curious as to why you chose to run an electric pump. The mechanical pumps are damn near bulletproof IMO...and not overly expensive. I've never really had a problem with one. I use the kyosan pumps.
 
Once the float level is correct and the needle is seated as it should be the use of an electric pump is no problem, regardless of if the engine is running. The return line is also not needed provided the pressure is correct (2 psi is too low).

The only downside to electric inline pumps is the noise and that because of no cooling (such as in sump pumps) they overheat and quickly fail. The downside to not having a return line (and the pressure being too low) is vapor lock. For that engine/carb the pressure should be at least 5 psi at idle, don't go above 7.
 
Too much fuel pressure is a real possibility you have a site plug on the side of the fuel bowl. Adjust the fuel level to just below the hole with the plug out.
 
Rice said:
The only downside to electric inline pumps is the noise and that because of no cooling (such as in sump pumps) they overheat and quickly fail. The downside to not having a return line (and the pressure being too low) is vapor lock.
Click to expand...
Shiiit. Now you've jinxed me. I kind of like the noise, though...lets me know it's working!
 
I swapped mine out for a Koyosan, also. no problems since
 
Rice said:
Once the float level is correct and the needle is seated as it should be the use of an electric pump is no problem, regardless of if the engine is running. The return line is also not needed provided the pressure is correct (2 psi is too low).

The only downside to electric inline pumps is the noise and that because of no cooling (such as in sump pumps) they overheat and quickly fail. The downside to not having a return line (and the pressure being too low) is vapor lock. For that engine/carb the pressure should be at least 5 psi at idle, don't go above 7.
Click to expand...


I have had the Facet pumps run for years. They are an OEM supplier and the pumps are solid
 
Rice said:
Once the float level is correct and the needle is seated as it should be the use of an electric pump is no problem, regardless of if the engine is running. The return line is also not needed provided the pressure is correct (2 psi is too low).

The only downside to electric inline pumps is the noise and that because of no cooling (such as in sump pumps) they overheat and quickly fail. The downside to not having a return line (and the pressure being too low) is vapor lock. For that engine/carb the pressure should be at least 5 psi at idle, don't go above 7.
Click to expand...

You're saying that a running electric fuel pump without a return will not overcome the pressure of the float pressing the needle valve into the seat?

Can you elaborate?
 
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