damn speed demon carb, accelerator pump issue (FIXED!)
#119810
09/13/08 12:48 AM
09/13/08 12:48 AM
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Joined: Aug 2004
Posts: 2,773 S/NH
hemijimbo
OP
master
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OP
master
Joined: Aug 2004
Posts: 2,773
S/NH
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been working on a friends 383 rr, he has a 750 speed demon carb , he purchased new last year, it works fine for the most part, but has always had a stubborn flat spot just off idle, we traced it back to the accelerator pump, when you move the linkage by hand, you can get about a 1/4" of movement and the first drip of fuel comes out of the squirter, if you move it further, then the "squirt" action takes place, it doesnt start its fuel squirt when it should, its like theres air getting in the pump some how, we have replaced the diaphragm, tried larger nozzles, talked to tech at barry grant (what a joke), still no answers, how or what would cause the pump to drip a drop of fuel rather then shoot it??, it has the stock pink cam, that comes with most of the 750.s, we even tried changing the rubber check valave and gaskets, still no squirt for the first part of opening the throttle...were miffed, any help or insight greatly appreciated
Last edited by hemijimbo; 09/13/08 03:47 PM.
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Re: damn speed demon carb, accelerator pump issue
[Re: hemijimbo]
#119812
09/13/08 08:30 AM
09/13/08 08:30 AM
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Joined: Jan 2003
Posts: 5,443 Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,443
Indiana
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The pump cam may be on #2 or #3 mounting hole. Pull the pump cam screw and double check to make sure it is on the #1 hole for immediate reaction. If the pump cam is already on the #1 hole, then lengthen the pump cam bolt 1/4 turn at a time then test to see if that activates the pump arm quicker.
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
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Re: damn speed demon carb, accelerator pump issue
[Re: YO7_A66]
#119813
09/13/08 11:07 AM
09/13/08 11:07 AM
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Joined: Jan 2003
Posts: 17,844 S.E. Michigan
ZIPPY
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,844
S.E. Michigan
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Good advice so far. While you're at it, also clean out the passage between the top check needle and the pump itself, make sure it has a check needle and it's working properly, and make sure the squirter gasket is present and isn't leaking.
Rich H.
Esse Quam Videri
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Re: damn speed demon carb, accelerator pump issue
[Re: hemijimbo]
#119815
09/13/08 03:02 PM
09/13/08 03:02 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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I seriously don't believe it. My squirter problem is finally solved!!!!! Hemi Jimbo is a virtual God in my book! The man just wouldn't give up. After all this trouble it turns out that there are two small brass set screws in the circuit of the metering block controlling the squirter. Jimbo took note that both screws were barely screwed in and only one had sealant or lock tite on it. We took them out cleaned them up and applied lock tite to both set screws and set them in to bottom out making certain they would not protrude into the circuit and interrupt flow. I'll be damned! That solved it. It appears air was being sucked in by the loose screw threads. Once again nice QC at Barry Grant. I want to thank all you guys for your helpful input.
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