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Old 01-25-2006, 04:33 PM
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Holley 750 Carb Leak

I have a holley 750 carb (3310S) that I bought from a buddy. He bought it new and didn't use it so he sold it to me. It has never been used prior to my installation. The problem I have is fuel is leaking from the secondary throttle shaft after I shut off the engine. It is leaking on the non-linkage side of the carb. I have talked to holley tech support and they think it is the bushing on the shaft. I don't understand why it only leaks after the engine is shut off, and the carb is new so the bushing couldn't be wore out. I no absolutly nothing about carbs, so any insight or thoughts on the problem is very much appreciated.

Thanks!!

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Old 01-25-2006, 04:39 PM
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I really hope the holley guy was joking. The shaft bushing is not designed to keep in gas!

First thought is that the float is too high and running over in the secondaries. Could also be some crud under the needle causing the needle and seat to not fully seal up and stop the fuel.
If you don't know much about carbs, i'd suggest trying to find someone to help straighten it out.

Mark
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Old 01-25-2006, 05:17 PM
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No, the holley guy I was talking to wasn't joking. I checked the float level and it is right below the sight plug, with the engine running at full temp. I have a 1" spacer, so I don't think fuel perculation is a problem. You did mention the needle not seating. On new carbs, do you have to take them apart and clean them before you install them?

Thanks for the Help!
I am learning more and more each day!
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Old 01-25-2006, 06:50 PM
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I've not yet found a Holley that didn't drip gas from the secondary throttle shaft. If it works fine, aside from the dripping, I wouldn't monkey with it.

You can get an aftermarket baseplate with sealed shafts if it bugs you that much.


Larry
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Old 01-25-2006, 09:07 PM
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Is it really that common of a problem on holley carbs?
It runs fine, just leaks fuel after I shut off the engine. I have an edelbrock carb that I took off the motor, I am wondering if I should just rebuild it and put it back on? I am really not happy with gas sitting on the intake with the holley!
Any other thoughts on the holley??

Thanks for info!!

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Old 01-26-2006, 05:13 AM
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[QUOTE=tweeter400]Is it really that common of a problem on holley carbs?
QUOTE]

No, it is not that common. I have run Holleys all my life and I have had only one that did what you describe. It was a used one and it was fixed with a quality rebuild kit.

Vince
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Old 01-26-2006, 06:21 AM
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carb

I am with Vince, there is no reason for the shaft to leak fuel. I have never had a holley do this on any of my cars...

One thing with fuel leaks some times they will start another place and trickle to the lowest point. So make sure that it really is coming from around the shaft... The holley tech guy must be on crack!!! If that carb sat, even tho it was never run it should at least have new gaskets installed. They do shrink even with-out fuel.... the other thing that everybody misses with carbs is the fact that once they are on the engine and up to temp they need all the bolts re-tightened....

It might be a situation where the fuel is perculating. You might want to try a insulating gasket between the carb and intake and see if that fixes the problem....After the car sits look down inside the rear ventures and see if they are wet with fuel...

Keith
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Old 01-26-2006, 06:29 AM
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Leak

I had this problem with my carb spoke to holley they said it was't possible, but if it did, tighten the butterfly head bolts from the bottom of the carb. I did this and the leak stopped.
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Old 01-26-2006, 05:14 PM
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I have a 1" spacer, so I don't think it is fuel perculation. It will leak if I just fire the truck for 2 minutes and shut it off. I am positive it is the secondary shaft leaking. I am going to take off the carb this weekend and tighten the screws and check the needle and seat for junk.

Any other thoughts I should look at while I have the carb off??

Thanks for all the replies!!
This forum has a lot of great members!

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Old 01-27-2006, 05:21 AM
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carb

Yea, check all the bolts... Did you look inside to see if the rear venturies are wet???

There is no fuel around those shafts, So if it's leaking there then it's coming from another place........above them
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Old 02-05-2006, 03:28 PM
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Hey ... just wondering how you made out with this. I am having a similar experience with my brand new 750 DP. When I hit the brakes hard it stumbles and wants to stall, and will unless I rev it up to keep it from stalling. Then the car is hard to start (I think it's flooded) and runs like crap at low rpm's. Today about 10 seconds after the car stalled I noticed a trickiling sound from under the hood and found fuel just pouring onto the throttle blades. So I restarted the car and observed at idle and fuel is just pouring out and pluddling up. The car stalled and I took the pic below.

Is there a cure for this? And would hitting the brakes hard start the problem?

Thanks, and sorry for the threadjacking.
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Old 02-05-2006, 03:40 PM
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Quote:
Originally Posted by 72Orange
Hey ... just wondering how you made out with this. I am having a similar experience with my brand new 750 DP. When I hit the brakes hard it stumbles and wants to stall, and will unless I rev it up to keep it from stalling. Then the car is hard to start (I think it's flooded) and runs like crap at low rpm's. Today about 10 seconds after the car stalled I noticed a trickiling sound from under the hood and found fuel just pouring onto the throttle blades. So I restarted the car and observed at idle and fuel is just pouring out and pluddling up. The car stalled and I took the pic below.

Is there a cure for this? And would hitting the brakes hard start the problem?

Thanks, and sorry for the threadjacking.
You either have too much fuel pressure overriding the needle and seat , too high a float level , or something (most common pipe tape which has no buisness on any fuel fitting ) not letting the needle and seat close.
Have had all of the above happen at one time or another.
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Old 02-05-2006, 03:55 PM
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Quote:
Originally Posted by dgcantrellsr
You either have too much fuel pressure overriding the needle and seat , too high a float level , or something (most common pipe tape which has no buisness on any fuel fitting ) not letting the needle and seat close.
Have had all of the above happen at one time or another.
Thanks for the reply.

Fuel pressure is normal.

Float level is perfect.

Sounds like I need to check the needle and seat. I did just install stainless braided. Maybe I got a piece of braid in there. There is a TINY bit of teflon where the gauge goes into the adapter.

Thanks again for the reply. Would this problem normally pop up during hard decel?
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Old 02-05-2006, 07:33 PM
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commonality...

A lot of carburated vehicles end up stalling on hard decel when not set up properly, I have a Holey remanufactured rochester carb that does the same thing. The only problem is you can't check the float level because the float is attached to the upper float bowl cover, and you can't seat the needle without closing the carb...
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Old 02-05-2006, 08:45 PM
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Did you have a float sink?

Quote:
Originally Posted by SecGenLvr
The only problem is you can't check the float level because the float is attached to the upper float bowl cover, and you can't seat the needle without closing the carb...
SecGen, you can measure the floats though. There is a measurement they need to be set to. If they're too high or too low you're going to either have not enough or too much fuel in the bowl.

Last edited by Blazin72; 02-05-2006 at 10:02 PM.
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