Holley 1940 Adjustment

[Batman1458]

66 Mustang coupe (Sig has vehicle specs)

Anyone have any info on adjusting a Holley 1940 carb? The car starts fine and runs ok, but I think it may be idling a little fast. I have adjusted the timing, it was almost vertical on the block, after installing Petronix II, I tuned it down to about 10 degrees. The book says to adjust it to 6 degrees, but I find a little advanced works better in these cars. My 66 vert runs best about 14-15 instead of the 12 that is mentioned in the manual.

I am probably going to retard the timing a little more before messing with the carb, but wanted to get some advanced advice on the adjustments for this carb. I live in NJ and the average temp right now has been between 25 and 35 degrees F.

Thanks for the help.
Ed

 

[MPGmustang]

first, i think the holley 1940 is very picky...

the carb has three things you can set:
Cold Idle (by spinning the plastic cap with a screw driver)
gas/air ratio
lowest idle

the cold idle is obivious just keep it 1/8-3/16th of an inch open it will auto adjust your low idle, if it works to start the car in the morning then leave it be

the low idle is best set when the engine is warm... use a tach if you have a auto set for 750-850 rpm, a manual can go as low as 550-700, depending on condition of engine, the lower and more steady the better shape your engine is (if it's stock)

the gas/air screw same time the low idle.... set the low idle then change this screw for the best rpm make it run the fastest (it's okay to try bigger ranges than 360* you're tunning it for it's best place, try anything that's how everyone did it by trying it out if it didn't work you'll know)
then just go back and forth, untill you find you engine's best idle, more of a sound than the actual rpm range but you'll know when you hear it, it's more of what the engine likes, it should be smooth ish.
find the full range you can set this screw to without it sputtering, or choking. then set it 50% ish in that range (by screwing it in and out, it could be 1.5 turns for this entire range where you want it to be .75 turns from the "innest/outest")
from here you can do 1 of 2 things:
1. keep it right there ish
2. screw it in to lean it out without changing idle speed/sound (i choose this, it does make the engine run warmer though, good for colder weather, bad for arizona heat )

try both on what you like for throttle response when driven.

if you have an auto rpm should be 750 in park/neutral and 550-650 in gear, i installed a 0-6k rpm tach as i'll never hit 5 anyways.. can't even break 4k but a worthy upgrade from summit (part number 2306)

take your time, test drive, enjoy.

the timing- ()

this has been a real for me, i didn't have my vac-advance modual working so i didn't know at the time.. now it's fixed that that's fixed i set to to pony carbs recomends, i'll try my uncles tip tomorrow, carefully.
"pony carbs video says"

if it's in the right tooth a 68 and later 200, the vac-advance modual is pointing to the firewall, a little more to the driver's side than straight to....
the pre-68's need the vac-advance modual pointing between cyl's 5-6 (more leaning towards 6 but not quite)

this is how mine is currently set up (i have a 68 200 in a 65mustang)

test test test....

"what my uncle said"

loosen the bolt for the distruibutor enough to where is doesn't come out but is finger loose with the bolt and plate still keeping it in. have some one start the engine while you watch/hold the distributor still, if you have it right the engine will put it to where it likes it, you will feel it almost guide itself

haven't tried it yet but i will tomorrow after i fix my exhaust gasket, i'll let you know how it goes. (probably blow myself up.... )

hope this helps,
Richard

 

[mugsy]

Ed,

You're adjusting the time with the vac tube to the vac canister disconnected, right?

tanx

 

[Batman1458]

Mugsy, yes, I disconnected the vaccuum advance. I think I might time it a little closer to the 6 degree mark and see if that makes a difference, before I tweak the carb.

MPGMustang, thank you for the details, but do you have or know of any diagrams that would show me where the specific screws and adjustments you speak of are? I am familiar and have diagrams on an Autolite 1100, but the holley.

Thanks for the help!
Ed

 

[mugsy]

From what I've read, the stock initail timing is determined amoung other things for emissions. Most cars (mine included) like more initial timing. Things we can do as owners is different than what the OEM had to do. If the car likes more initial I say set it and forget it.

 

[MPGmustang]

Batman,

Pictures, I think I have some, this is my 1940 holley that I took off of my Car.

this is the rear veiw, the left side is the idle screw, the right side is the gas/air ratio adjustment

this is the front right side, the top arrow is the choke adjustment, the bottom arrow is the gas/air screw....

hope this helps
Richard

 

[Batman1458]

Thanks MPGMustang! This really helps! As soon as I can get some time away from my job and my two or three side jobs, I will start making the adjustments you mention.

I will probably not attempt to adjust anything, except when I fill up and see how these adjustments affect my gas mileage. Right now I am getting about 15.6 MPG, but that is only based on one tank full. I think I have most of the bugs worked out and the major safety repairs done. The car should be on the road consistently from now on.

The only major issue that I have left is the problem I have with the clutch, but that will be in my next post.

Thanks again!
Ed

 

[MPGmustang]

no problem, i found that if i rasied the idle i a can lean the gas/air ratio more, although it raises temp i got 19mpg once... before i put on my v1100, it wouldn't beadvisable for long road trips as temp seems to be my prblem with the a/c on but was fun while it lasted, i'm now enjoying my average 18mpg intown and 21mpg freeway v1100

Good luck
Richard

 

[mugsy]

I ran a 1940 carb for about 7 years and thought it was a great carb. After it was rebuilt and set up right it ran without a hiccup. Hopefully you'll find you carb as reliable as mine.