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holley pump shot question #1531915
11/11/13 11:43 AM
11/11/13 11:43 AM
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indiana
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mcmopars Offline OP
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holley 750 street h.p. vac. sec.full throttle under load acceleration is great.at idle in park when i hit the throttle fast it stumbles for a bit before picking up.i get fuel as soon as i give it gas,so i assume the pump shot is adjusted correct.not sure if its a shooter issue?timing is 38,vac.advance is not used.i know its a tunning issue,just wondering what i need to play with?shooter size?

Re: holley pump shot question [Re: mcmopars] #1531916
11/11/13 12:01 PM
11/11/13 12:01 PM
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GomangoCuda Offline
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need to know more about the combination.

engine size, compression ratio, cam specs, timing at idle speed(very important), Manual or automatic transmission, converter, gear ratio, car weight and anything else you can think of.

Most likely a timing curve change and/or accelerator pump nozzle change will be the solution but if the combination details listed above are out of wack to each other it will be more difficult to fix.


In theory, there is no difference between theory and practice. In practice, there is.
Re: holley pump shot question [Re: GomangoCuda] #1531917
11/11/13 12:12 PM
11/11/13 12:12 PM
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indiana
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360,544/228,9.5 3200,not sure timing at idle,i set it at 38 deg.at 3500 rpm,float set to just dribble out of hole,9.5-1 compression.mp dizzy otb.chrome ign box.

Re: holley pump shot question [Re: mcmopars] #1531918
11/11/13 12:18 PM
11/11/13 12:18 PM
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GomangoCuda Offline
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Quote:

360,544/228,9.5 3200, not sure timing at idle,i set it at 38 deg.at 3500 rpm,float set to just dribble out of hole,9.5-1 compression.mp dizzy otb.chrome ign box.




There is your problem. The MP distributer has way too long of an advance curve. For an explanation of how this happened see here. http://www.moparts.org/Tech/Archive/elec/29.html


In theory, there is no difference between theory and practice. In practice, there is.
Re: holley pump shot question [Re: GomangoCuda] #1531919
11/11/13 12:26 PM
11/11/13 12:26 PM
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indiana
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Quote:

Quote:

360,544/228,9.5 3200, not sure timing at idle,i set it at 38 deg.at 3500 rpm,float set to just dribble out of hole,9.5-1 compression.mp dizzy otb.chrome ign box.




There is your problem. The MP distributer has way too long of an advance curve. For an explanation of how this happened see here. http://www.moparts.org/Tech/Archive/elec/29.html






after reading this
i must be stupid,because i really didnt understand what i need to do.

Re: holley pump shot question [Re: mcmopars] #1531920
11/11/13 12:47 PM
11/11/13 12:47 PM
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GomangoCuda Offline
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Sorry, should have given these links also.
http://static.summitracing.com/global/images/instructions/maa-29014%282%291.pdf Follow the instructions and pictures for the YH advance. You can use drill bits instead of the keys shown like the guy did in the next link.
http://www.moparts.org/Tech/Archive/elec/25.html
Or buy the kit. http://www.summitracing.com/oh/parts/maa-29014/overview/

You will probably need 16-18 degrees at idle. Trial and error will get you there.

Last edited by GomangoCuda; 11/11/13 12:59 PM.
Re: holley pump shot question [Re: mcmopars] #1531921
11/11/13 01:46 PM
11/11/13 01:46 PM
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Lincoln Nebraska
RapidRobert Offline
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Assuming no vacuum leak & float levels correct & as you said when you barely pull the throttle by hand at the carb you want an immediate stream of gas "tip in" & a stream of sufficient duration. What's your initial & is it on ported or manifold. EDIT reread & saw that no vac adv is used

Last edited by RapidRobert; 11/11/13 01:52 PM.

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Re: holley pump shot question [Re: RapidRobert] #1531922
11/11/13 01:52 PM
11/11/13 01:52 PM
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indiana
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i have the vaccum advance capped off at the distributor.all in at 3k or so.set at 38 deg.it runs great other than when you give it a quick jab at the throttle in park

Re: holley pump shot question [Re: mcmopars] #1531923
11/11/13 01:57 PM
11/11/13 01:57 PM
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ademon Offline
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make sure your initial is at 15 to 20, and sqirter size may need to be in the 30 to 32 range

Re: holley pump shot question [Re: GomangoCuda] #1531924
11/11/13 04:42 PM
11/11/13 04:42 PM
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Overpriced Housing Central
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Quote:

Quote:

360,544/228,9.5 3200, not sure timing at idle,i set it at 38 deg.at 3500 rpm,float set to just dribble out of hole,9.5-1 compression.mp dizzy otb.chrome ign box.




There is your problem. The MP distributer has way too long of an advance curve. For an explanation of how this happened see here. http://www.moparts.org/Tech/Archive/elec/29.html




Got that right. Initial timing is a likely culprit.

Re: holley pump shot question [Re: ademon] #1531925
11/11/13 08:05 PM
11/11/13 08:05 PM
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indiana
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Quote:

make sure your initial is at 15 to 20, and sqirter size may need to be in the 30 to 32 range






ill check the timing(initial) in the morning.then ill see what squirter is in there now and go from there.thanks

Re: holley pump shot question [Re: mcmopars] #1531926
11/11/13 08:39 PM
11/11/13 08:39 PM
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Benton, IL.
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DaveRS23 Offline
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Timing, both initial and advance rate and pump shot are good areas to start with. The only thing I would like to add is to check the power valve opening point. You may try an earlier opening one.

Timing and fuel. You either need more of either or need what you have sooner.


Master, again and still






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