Tuning a Holley one barrel carb
- Thread starter Pete W
- Start date
x21
Well-known member
How about exploded views? http://www.tocmp.com/manuals/Carbs/Holl ... /1908.html
Mercury Mike
Famous Member
Turn the mixture screw in as far as it will go until it starts stumbling, and then out until it starts stumbling, and then in until it starts stumbling, and then out like 2 and a half turns or so. I usually do it until it's really smooth, then use a tach to find the right RPMs on the idle speed. Make sure that your timing is correct BEFORE you adjust the idle screws.
You dont have a Load O Mattic dizzy do you?
If things were not perfect before the swap its going to take some back and fourth getting things closer and closer every time so dont expect things to be perfect after 5 minutes of messing with it.
If things were not perfect before the swap its going to take some back and fourth getting things closer and closer every time so dont expect things to be perfect after 5 minutes of messing with it.
Tell me if this is right....
My Holley 1904 idle speed screw is turned all of the way in and the mixture screw is about three turns out to give me an RPM of about 700 with the choke open all of the way.
Will this fly? Seems like I shouldn't have the idle speed screw turned all of the way in. Forget the mixture screw 1 1/2 turns back from seated to start like the manual says. The car will never run at that setting.
My Holley 1904 idle speed screw is turned all of the way in and the mixture screw is about three turns out to give me an RPM of about 700 with the choke open all of the way.
Will this fly? Seems like I shouldn't have the idle speed screw turned all of the way in. Forget the mixture screw 1 1/2 turns back from seated to start like the manual says. The car will never run at that setting.
If you can afford it, you should go buy a timing light.
If you can't (40 bucks) then you should turn the distributor ccw a little at a time until it pings under load, then turn it back a little until it stops.
That will get you close. At that point, try setting your idle.
However, you are basically pissing in the wind without a timing light.
If you can't (40 bucks) then you should turn the distributor ccw a little at a time until it pings under load, then turn it back a little until it stops.
That will get you close. At that point, try setting your idle.
However, you are basically pissing in the wind without a timing light.
Carb problems and dizzy problems have the SAME exact symptoms. If the dizzy isn't right you can fiddle with the carb all day and night and never get it right. THE FIRST STEP IN ADJUSTING A CARB IS TO SET THE DIZZY UP RIGHT.
There are a few items on the dizzy that have to be correct. Make sure the initial timing is right. This effects the idle speed. Also verify the point gap/dwell. This has a huge effect on the idle quality. you can set the initial timing by either a timing light (most prefered) or the "advance until it pings at speed and back-off" method. As for the points gap, its either a feeler gauge or dwell meter. I like the dwell meter.
As for the carb, get it up to operating temp. Make sure the choke is off. Then set the idle speed first. I like to use a tachometer for this. Then adjust the idle mixture screw. I like to use a vacuum gauge. Adjust to the highest reading. You can also use the the tach, and adjust to highest speed. This will more than likely change the idle speed, so go back to that and adjust the speed to your spec. Then go back to the idle mixture screw. And do this one more time. I usually do the "idle speed-idle mixture screw" adjustment thing three times and call it good.
tanx,
Mugsy 8)
There are a few items on the dizzy that have to be correct. Make sure the initial timing is right. This effects the idle speed. Also verify the point gap/dwell. This has a huge effect on the idle quality. you can set the initial timing by either a timing light (most prefered) or the "advance until it pings at speed and back-off" method. As for the points gap, its either a feeler gauge or dwell meter. I like the dwell meter.
As for the carb, get it up to operating temp. Make sure the choke is off. Then set the idle speed first. I like to use a tachometer for this. Then adjust the idle mixture screw. I like to use a vacuum gauge. Adjust to the highest reading. You can also use the the tach, and adjust to highest speed. This will more than likely change the idle speed, so go back to that and adjust the speed to your spec. Then go back to the idle mixture screw. And do this one more time. I usually do the "idle speed-idle mixture screw" adjustment thing three times and call it good.
tanx,
Mugsy 8)
