Need advice on my Holley DP 650

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340inabbody

340inabbody

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So I am going back to basics on tuning my carb and I am not claiming to be experienced on it at all. So your advice is needed and appreciated.

Initially I checked float height and it was fine on both primary and secondary. Recently I checked again since I think that is the starting place. The primary is good but the secondary is low and no matter how much I back the nut off CCW the level doesn’t come up.

Anyone have any advice other than pulling the bowl and inspecting the float assembly or if that what to look out for like a hanging spring etc?

Thanks
Ron

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Last edited:
GTX JOHN said:
You need to remove the bowl.

Not a big job.

I have never encountered that particular issue.
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Thanks John I kinda figured I might need to do that. Is there an easy way to drain the bowl? Also where is a good place to get an exploded view/drawing for the carb?
 
Lightly tap the adjuster. See if the needle is stuck, but it is no big deal to get in there. Get a set of new gaskets, the re-useable ones. I used to just pull the carb off and turn it upside down over a tray. Easier to play with it on the bench.
 

furrystump said:
Lightly tap the adjuster. See if the needle is stuck, but it is no big deal to get in there. Get a set of new gaskets, the re-useable ones.
Click to expand...
I actually tried that last night. I think it’s ok now but have to check float height and see! Thanks!
 
I can’t remember, been a while since I played with a Holley, but it might have a small wire clip that attaches to the float arm. It “should” pull the needle out of the seat. The clip might be off. I would want to look at it, if there is something off with the needle and seat it can go the other way and fill the bowl and pour out of the vent and dump raw fuel into the motor. With an electric pump you can hydra lock the motor that way or just dilute the oil with raw fuel.
 
Take the bowl off and remove the needle and seat. Make sure it is clean and moves freely. They can get dirty and stick and the float won’t adjust.
Make sure the arm that attached to the float is clean and moves freely.
Check the float to be sure it has not filled with gas. This can happen if a pin hole or crack develops a hollow float.
 
Depending upon the age of the needles and seats, the Viton tip of the needle may have a slight groove in it. This can cause fuel to seep by and over fill the bowl, my suggestion would be to pick up a pair and change them out.
 
You can change the needle and seat assembly without removing the bowl.
 
To drain the bowl, cut a water bottle in half and remove one of the lower bowl screws. Use the bottom half of the water bottle to catch the fuel out of the lower screw hole.
 
You dont need to remove the bowl to check the needle and seat. Just unscrew it and pull it up. When you re install it, go down further (leave about 3 threads showing above the bowl) then you think you need to. It’s easier to adjust the level up than down. To adjust it you have to have the fuel pump running, and the engine using fuel, to get the most accurate level.
 
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