How to tune the Holley 750 on my 440....

[Blakcharger440]

I have a brand new Holley 750 vacuum secondary carb with electric choke on my 440 and I am needing some tips on tuning it and timing the engine.

So far when I fire the engine up the revs are very high so I turned it off.

The Holley tuning manual says that the carb is factory set for an idle of 1500-1600rpm which is too high.

It says to turn the Fast Idle Speed Screw clockwise to increase the RPM and counterclockwise to decrease the RPM,..is that correct because the screw as it sits right now (factory setting) is mostly screwed outward.

Specs of the engine are

1967 440 with 915 heads stock
TM7 Edelbrock intake (gonna swap it out later)
flat tops at .070 in the hole
MP 484 cam
1 7/8 Headers
MP elecronic ignition
750 Holley,Vac Secondary electric choke

[aifilaw]

There's too many things that need to be adjusted to make it perfect to list... I used to have a 3 or 4 page article with pictures and extensive details and what everything did, et cetera on the old site, but I can't find it anymore, it may exist somewhere on my hard drive, I'll look.

Mostly turned all the way out on the idle screw (which effects the throttle body directly) should be nearly all the way out all the time, but you will find half a turn can effect your RPM's by a few hundred, adjust it while its running, that won't hurt anything.

Other things that will effect a high idle are (vacuum leak due to ports not being plugged), idle mixture screws (those little screws going into the metering block on the left and right side of the carb, they are brass and stick out and are quite small), and of course your main jetting.

[Ghoste]

I think that somewhere on this site you should be able to find Chryco Psycho's world famous Holley tuning guide.  It's a must have.

[Chryco Psycho]

you may need that especially since I have not logged in in well over a month
I suspect you have another vacuum leak either under the carb , in the brake booster etc , or the carb gasket has the throttle plates jammed open

[firefighter3931]

  Check the throttle cable and make sure the blades aren't hanging up. Also look at the linkage as well....there is a Mopar specific adapter that you need to use when installing a holley carb. 


Ron

[Steve P.]

Also make sure the choke blade is wide open and not holding the throttle open on the cold idle cam..

Start the motor and manually open the choke blade. Then just blip the throttle a touch. This should drop the idle down to the hot run position.

Make sure you do your carb tuning with the motor at normal running temps.  The choke blade will need to be adjusted according to your ambient temps.  Follow the instructions. they will get you most of the way there. Fine tuning is a learned art. Just take it one step at a time and make sure you understand what you are doing before you do it..

[aifilaw]

first thing I do with any carb is wire the choke blade open.... unless it gets below freezing its worthless, and if it does, I would unhook the electrical choke control and wire a manual cable to it.

[john108]

Chryco Psycho post:

http://www.dodgecharger.com/forum/index.php/topic,12415.0.html