Quick 600 holley double pumper tuning tips please???

[bleedfordblue65]

I just ordered a 600 double pumper for my 289 and Im looking for some help to get it running good. Heres my combo... 289 block, mild GT40 heads, Comp 270H magnum cam, Performer RPM intake, Hooker headers, 5 speed, 3.55 trac-loc, stock fuel pump (also need suggestions on upgrades for that) ect. If any one out here has a similar set-up and can help me get this thing set dry I would appreciate it. (i.e. how many turns out each screw should be) I am carb illiterate and would need things in dummy terms. I am trying to learn as much as I can so I can get this thing tuned myself but I just need a push start from the experts. Thanks a lot guys...

Brett

 

[TOM B]

I had a setup just like this when I was 24 years old and had a 65 mustang cp.
Very cool, very fast car. Does your DP carb have vacuum or machanical secondarys. I had mechanical on mine. Adjust the air and fuel screws by turning them in till they stop,, TURN LIGHTLY, NO FORCE!! then turn both
2-1/2 turns out. Start it up and worm up. Then turn them out another full turn. Then turn each one in till the engine slows,, or use a tach and just when you see the RPM's drop, STOP. and turn that screw out 1/2 turn then do the other the same way. Then readjust your timing, you will need more advance to burn more fuel. If you have the room under the hood, raise the carb up with a spacer, start with a half inch, A spacer will raise the RPM level and mix the fuel better. If it stumbles when you floor it, repost here and we will work on that.
P.S. I then went to a bigger cam and DUEL Holley 600 carbs, WHAT a RIDE

 

[D.Hearne]

Hope you've got the 58 cc GT40 heads. Otherwise you're going to loose about 1 full point compression with 64 cc heads. Take the 58's, if that's what they are, and mill them .030 before putting them on. As to the carb, turn the mixture screws in all the way till they bottom, then out 1 full turn each. On the throttle-idle screw ( driver's side of the linkage, turn it out all the way till the linkage stops moving, then in just until it moves the throttle, no more. Too much and you'll expose the transfer slots in the bores ( tiny slots just above the throttle blades) and no matter how you adjust the mixture screws, there will be no effect. Also adjust the gap between the accellerator pump arm and levers till there's no gap, the pump should spit fuel as the throttle moves. Remove all the choke parts, you don't need it. I'm 60 miles west of you and I have no choke on any of my Holleys.

 

[bleedfordblue65]

All i really know about the heads is they were off a lightning and they were shaved .040.

D.Hearne let me get this straight... Back out the idle mixtures 1 full turn then leave them alone? Then set the idle screw so that it barely moves the throttle linkage? will I need to change the power valve? What about the jets? Since I am buying the carb used, should I go through it and blow it out or will that hurt anything? Also, when I check the vacuum, What do I hook up the guage to? Will I need an air/fuel guage to get it set perfectly? Will I need to upgrade my fuel pump? electronic or mechanical? Thanks again, the help is really appreciated...

Brett

 

[D.Hearne]

All i really know about the heads is they were off a lightning and they were shaved .040.

D.Hearne let me get this straight... Back out the idle mixtures 1 full turn then leave them alone? Then set the idle screw so that it barely moves the throttle linkage? will I need to change the power valve? What about the jets? Since I am buying the carb used, should I go through it and blow it out or will that hurt anything? Also, when I check the vacuum, What do I hook up the guage to? Will I need an air/fuel guage to get it set perfectly? Will I need to upgrade my fuel pump? electronic or mechanical? Thanks again, the help is really appreciated...

Brett

What I posted will get you started. You didn't say it was used. If so, bolt it on, start it up and see if and how it runs. Chances are if it's sat any length of time it'll need to be rebuilt, or maybe just the accellerator pump diaphram and power valve replaced. Both are rubber parts and will get dried out and rupture when used.The needle and seat assembly's will probably also need replacing, it doesn't take much trash or corrosion to make em stick open.(or fuel pressure either) Replace the power valve with the same one it had, chances are it's the correct one ( usually a 6.5) I never check the vacuum or air fuel ratio, I just take the time to read the spark plugs. You present fuel pump should be plenty, most are. I fed my 331 sixpack with a low pressure, 30 gal/hr electric. Only time it ran short was when the inline filter ahead of it got plugged with gunk. Jets don't need replacing untill you've got it running long enough to read the plugs, you have to do this after full power runs or driving it hard on the highway. You CANNOT get an accurate reading from running it in the driveway.

 

[bleedfordblue65]

Thanks a lot, Ill let ya know whats goin on after I get it on. Ill also probably have some more questions. By the way, Do you know of any good books to read so I can learn about them? Is that the best way to learn? Thanks again,


Brett

 

[SoCalCruising]

Barnes and Noble and other bigger stores will have a book on Holley carbs.

 

[2bav8]

Do you know of any good books to read so I can learn about them?

Super Tuning and Modifying Holley Carburetors - I highly recommend this one.
It can be found at Amazon.com

 

[chepsk8]

Got a 600 DP on my 5.0 kin the Cobra, for the most part runs good. I am battling the car dying on hard stops. Done all the usual stuff, so just tweaking.