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Old 10-02-2018, 07:06 PM   #1
74CustomK20
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Holley help?

I'm hoping you all can help me with my Holley carb. I'm new to carbs as far as getting them to tune and run right, so bear with me. I know it's a 600 cfm, vacu secondary's, and manual choke. The issue (only one I know of) is when I punch it sitting in neutral (4 speed manual) it cuts out bad, but if I lean into it slower it sounds good and picks up rpm. Ideas?
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Old 10-02-2018, 07:56 PM   #2
geezer#99
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Re: Holley help?

Check your accelerator pump is working.
With the engine off look into the carb and stroke the throttle. You should see two nice streams of gas flow into the Venturi near the boosters.
Let us know what you see.

The Venturi is the air passage into the carb.
The boosters are those round things you’ll see inside.
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Old 10-02-2018, 09:03 PM   #3
GASoline71
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Re: Holley help?

Like geezer said, it might need more "pump shot". You can change the squirter size in a Holley carb to tune it to your needs.

Just curious, what is your timing set at?

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Old 10-02-2018, 09:10 PM   #4
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Re: Holley help?

Update, went out to the truck and with motor off, I stroked the throttle, fully, and no gas came out.
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Old 10-02-2018, 10:11 PM   #5
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Re: Holley help?

Without stroking the throttle, reach down and stroke the accelerator pump arm. It’s that little lever under the bowl. Push down on it.
If you still get nothing then it’s tear apart time.
If you get fuel it’s pump clearance that needs adjusting.
Can you take a pic of your carb at the front drivers side.
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Old 10-03-2018, 06:40 AM   #6
74CustomK20
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Re: Holley help?

I'll probably have to take it apart anyway, because it looks like it leaks gas (but not everytime) between the front block and mainbody. I get home I'll do that before I go out again.
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Old 10-09-2018, 08:35 PM   #7
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Re: Holley help?

Small update. Turns out when I pump the accelerator pump, I get nothing. So any help? Also took a pic of the driver front
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Old 10-09-2018, 08:42 PM   #8
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Re: Holley help?

Did you push on the lever or stroke the throttle?
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Old 10-10-2018, 03:13 PM   #9
74CustomK20
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Re: Holley help?

Geezer both. First stroke the throttle then push on the lever.
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Old 10-11-2018, 07:03 AM   #10
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Re: Holley help?

Most likely your check ball in the accelerator pump is stuck and not letting fuel to pass . You are going to have to take the front bowl off and clean it . Even if the acc pump diaphragm has gotten hard from age it should still move some fuel . Any movement to the pump assemble should produce some fuel out of it .

Put a new diaphragm in while you in there .


This not working proper will do exactly what you have happening .
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Old 10-12-2018, 03:31 PM   #11
74CustomK20
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Re: Holley help?

Good to know, any tips? I'm leaking fuel when. I shut the truck off anyway from the front area somewhere so this should work out good then... Any special tools or tidbits I should know? First Holley unfortunately.
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Old 10-12-2018, 03:41 PM   #12
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Re: Holley help?

Buy quality Holley branded gaskets and rebuild kits.
Be extremely careful removing and installing the bowl screws. They’re easily stripped.
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Old 10-12-2018, 06:20 PM   #13
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Re: Holley help?

Will do geezer. I'll look online at summit. Seems like I can always bring myself to buy enough to justify free shipping lol
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Old 10-13-2018, 08:04 AM   #14
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Re: Holley help?

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Originally Posted by 74CustomK20 View Post
Good to know, any tips? I'm leaking fuel when. I shut the truck off anyway from the front area somewhere so this should work out good then... Any special tools or tidbits I should know? First Holley unfortunately.
I have the same problem when one sits around much . The diaphragm and gasket starts to shrink . If pretty new you usually can snug the 4 screws on the diaphragm plate . Removing like you are and replacing should take care of your leak also .

No special tools really . Just basic stuff and all new seals and gaskets and you will be fine .
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