Holley help

Just had bilateral knee replacements so car has been laid up for a couple of years . Just got it running again but have a carb issue . One of the idle screws is leaking out fuel . My thoughts are stuck float or the small washer inside has deteriorated . Any ideas please

What type of carb? Check float level and or replace needle seals.

Have look on the side of the choke tower - the rectangular bit that sticks up on top of the carb. Stamped into the side will be a List number. You can look this up to see exactly which carb it is. If you need to check the float needle the you will need to remove the float bowl. The best thing is to buy a rebuild kit of trick kit for your carb. This will come with a new float needle, new blue Holley gaskets,new washers for the float bowl screws and new washers for the idle screws. The original Holley paper gaskets are crap and a pig to remove. The blue ones are good and easy to get apart and reusable.
The chances are that if the engine runs OK the float needle is OK and all you need to do is get new idle screw washers. A quick check is to remove the plug screw on the side of the float bowl. The fuel should just about seep out if the fuel level and float needle are OK. If fuel runs out constantly then it needs to be sorted. Lots of videos on YouTube or just ask on here.
All the parts you need can be bought from Real Steel

Holley list numbers here

Cheers
Mike

Thanks Mike and Bill .its a 750 Holley . And will check the float level tomorrow . If it is just the washer in the idle screw will be pleased . Might need to adjust the float level but as you say brilliant advice on U-tube. Does the carb have to be stripped to do the idle screw washer . i.e. the old one if damaged need to be hooked out ?

If you get tired of fooling around with dribbling gas on to your engine trying to adjust the Holley float level, buy a Proform or Holley Ultra. They have glass sight plugs that show the fuel level inside the bowl.

No the idle screw washer can be changed by removing the screw, changing the washer and replace. The old one is probably cork and can just be pulled out
Cheers
Mike

Don’t forget to screww the idle in and count the turns so you can put it back in the same place when you replace it.buy some washers for the float adjusting screw and nut on top of the float bowl as they are very thin and weak and easily broken when adjusting the float height. Again check how to do the adjust on YouTube.

Cheers
Mike

manta22 said:

If you get tired of fooling around with dribbling gas on to your engine trying to adjust the Holley float level, buy a Proform or Holley Ultra. They have glass sight plugs that show the fuel level inside the bowl.

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Love the look of that carb and such a logical improvement

It's a cheep fix if you stay with what you have. If you have to order parts have the list number handy, it"s on the air horn.

You need these. Just take the needle out, strip off the o rings, install new ones and reset float level.


Here's where they go:

So if the float valve shown above is bad, wouldn't that result in fuel coming out of the vent tube on either side of the the main body? Sounds to me like the idle adjustment valve o-ring/gasket needs to be refreshed. Lastly, I'm assuming this is an older Holley where the idle adjustment is for air, and not the later ones where it adjusts fuel? Thoughts?

blueovalz said:

So if the float valve shown above is bad, wouldn't that result in fuel coming out of the vent tube on either side of the the main body? Sounds to me like the idle adjustment valve o-ring/gasket needs to be refreshed. Lastly, I'm assuming this is an older Holley where the idle adjustment is for air, and not the later ones where it adjusts fuel? Thoughts?

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No, if the float valve is bad it should have fuel dribbling from both the booster venturis at that end of carb , I would check the corks on both the mixture screws, also possible that the gasket between metering block a main body might be crook/leaking and/or its the wrong gasket for carb in question.

Here is a very good resource on 4150 Holley's.

This guy may be a little bit red necky but he really knows his stuff on Holley's. I had to find him again but he has helped me quite a bit when I was trying to get my Holley to road race.