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Topic: 750 Holley DP adjustments.

in Forum: C3 Fuel, Emission Control, and Exhaust Systems

750 Holley DP adjustments.

Posted: 8/3/12 6:25pm Message 1 of 4
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Ocala, FL - USA
Joined: 9/14/2002
Posts: 72
Vette(s): 1975 coupe, Green, 4speed, T-top, 383 stroked, Hooker side pipes.
Beer Anyone have some tips on adjusting a Holley 750 DP carb ? I havent tinkered with it in awhile and I noticed some things. When I'm cruzn along N mash the gas it has some hesitation. So I checked under hood when I got home and started turning screws etc. It seemed to help some. Does anyone knoe how to properly set them up, such as Idel screw adjustment, accelerator pump adjustments. Are the accelerator pumps to be adjusted with some gap between bottom of adjustment nut N spring or tight up against ? Looks like I may have to buy a Holley book, I had one but lost it in all the moves over the years. My motor is a 383 CUI with Hooker side pipes, 4spd, 3.70 gears. 
 
Thanks gang,
ACE



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Re: 750 Holley DP adjustments.

Posted: 8/3/12 7:19pm Message 2 of 4
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
The accelerator pumps should be adjusted to where there is NO freeplay, but that pump lever is not actually moved..if that makes sense. You want to adjust it to where the screw just BARELY touches the pump lever arm.

Flat spots, if they are due to accelerator pump issues, can sometimes be corrected by changing the pump cam...the little nylon cam that screws on the linkage that the pump adjustment lever rides on.
At cruising speeds, the acc. pump really shouldn't be doing much anyway, but they do add a short skwert of fuel quickly, to overcome the flat spot....

hth



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Re: 750 Holley DP adjustments.

Posted: 8/4/12 12:14am Message 3 of 4
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Flanders, NJ - USA
Joined: 1/27/2004
Posts: 2553
Vette(s): 1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.
I had a hesitation on mine and I went up one size on the squirter and it got rid of the hesitation.
Dave



 

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Re: 750 Holley DP adjustments.

Posted: 8/4/12 4:06pm Message 4 of 4
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Ocala, FL - USA
Joined: 9/14/2002
Posts: 72
Vette(s): 1975 coupe, Green, 4speed, T-top, 383 stroked, Hooker side pipes.
Thanks for such a quick reply ! The nylon cam is it sized by color ? Also what about idel mixture screws on sides of metering blocks, R they to be like 1 1/2 turns out +- ? I need to do some tinkering this week while on vacation for sure.    Beer
 
Thanks again, ACE 



in Forum: C3 Fuel, Emission Control, and Exhaust Systems


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