Carb Question

Automotive powered airboat discussion.
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Duece
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Carb Question

Postby Duece » Tue Apr 21, 2015 9:08 pm

I have a ZZ4 350 with the 650 cfm Holley single pumper on it. The boat has always been very sluggish with throttle response. Runs good and all, just seems that when you stab the gas it loads up and then jumps to life. I had replaced the cams a few years back but it didn't seem to help. Is this just what you get w/a Holley 650, or...? Like most of my posts, you can tell I'm about as mechanically inclined as Martha Stewart (I know enough to be dangerous). Could possible be timing too I suspect? I have done nothing to the boat since day 1 from Diamondback except replace some bad jets in the carb about 5-6 years ago (maybe longer). Carb is 10 years old, but fires right up and idles great. Boat doesn't seem to be missing, just when you stab the gas it falls on it's face before catching up and then away she goes. Any ideas for helping get some more throttle response for a complete newbie?!

Duece
"Welcome to the Dark Side..."
14'x7'6" Diamondback ZZ4 350/355hp 2.37:1 Stinger gearbox 80" 3 blade NGR series

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Birddog247
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Re: Carb Question

Postby Birddog247 » Tue Apr 21, 2015 11:46 pm

I have a very similar setup to yours and asked the same questions when I built it. I was referred to Alan @ s&s performance carburater which provided good results. I went from not being able to break free on dry with and eldabrock to running wherever I wanted with a 670 cfm holly. Not sure what kind of magic he studied or maybe he kidnapped hoduinee.
12ft Palm Beach
stock 350sbc
2.1 gear/80"NGR

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rowdy1
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Re: Carb Question

Postby rowdy1 » Wed Apr 22, 2015 10:23 am

Check the accelerator pump, maybe even add a 50cc pump kit and "tune the cam that actuates the arm for the pump. With the motor off, look in the top of the carb and push the throttle to wide open with one smooth motion. Look at the squirters and see what kind of stream you get. Changing the pump is very easy, adjusting it is fairly easy as well.

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skinny99
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Re: Carb Question

Postby skinny99 » Wed Apr 22, 2015 11:27 am

Birddog247 wrote:I have a very similar setup to yours and asked the same questions when I built it. I was referred to Alan @ s&s performance carburater which provided good results. I went from not being able to break free on dry with and eldabrock to running wherever I wanted with a 670 cfm holly. Not sure what kind of magic he studied or maybe he kidnapped hoduinee.


Do yourself a favor and call Allen. Smart guy and unlike most carb guys is very familiar with airboats.
Successful people do what others won't or can't!

blow boat
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Re: Carb Question

Postby blow boat » Wed Apr 22, 2015 1:29 pm

rowdy1 wrote:Check the accelerator pump, maybe even add a 50cc pump kit and "tune the cam that actuates the arm for the pump. With the motor off, look in the top of the carb and push the throttle to wide open with one smooth motion. Look at the squirters and see what kind of stream you get. Changing the pump is very easy, adjusting it is fairly easy as well.



I had same problem also, order a accelerator pump cam kit
From Holley or quick fuel it come with like
6 different cams and play around with them
I ended out using the red one which is the
Largest if I remember corectly helped a lot !

LSX1
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Re: Carb Question

Postby LSX1 » Wed Apr 22, 2015 6:54 pm

The ZZ4 I had in 1999 had a 750 double pumper Holley and it was perfect it had a smooth idle, zero lag going from 2 barrel to 4 barrel and would run WFO for miles without any surging. It was turning a 80'' 6 blade warp set at 11 degrees pitch, 5100 rpm's with a 2.09 stinger gearbox. LSX1


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