idle running a little high.
Thread Starter
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Tuned
Joined: Jul 2011
Posts: 350
Likes: 3
From: Sacramento, CA
idle running a little high.
1966 F250 352 Automatic
Reman carb,
stickers on valve covers that read "Crower Racing Cams" (but I haven't opened the valve covers to check that they are actually in there),
Dwell meter reads about 27 degrees
Ignition timing at 10 degrees advanced
Vacuum gauge reads between 18 and 19 with a very light bounce
But my idle is at 650 rpm and no adjusting of the idle screw lowers it at all.
I haven't taken it out for a ride yet, I will tomorrow after I fix the ported vacuum tube that runs from the carb to the distributor.
How do I lower my idle?
Reman carb,
stickers on valve covers that read "Crower Racing Cams" (but I haven't opened the valve covers to check that they are actually in there),
Dwell meter reads about 27 degrees
Ignition timing at 10 degrees advanced
Vacuum gauge reads between 18 and 19 with a very light bounce
But my idle is at 650 rpm and no adjusting of the idle screw lowers it at all.
I haven't taken it out for a ride yet, I will tomorrow after I fix the ported vacuum tube that runs from the carb to the distributor.
How do I lower my idle?
Thread Starter
|
Tuned
Joined: Jul 2011
Posts: 350
Likes: 3
From: Sacramento, CA
I was kinda thinking that as well but the line I'm fixing is ported and I don't believe I get any vacuum there at idle. I put my finger over the tube hole and didn't feel any pressure...
It's dark and raining now so I won't get to it till tomorrow but I'd like to have a plan when I get out there.
Until then I'll be rebuilding my girlfriends tranny on her coffee table. Hope she doesn't come home.
It's dark and raining now so I won't get to it till tomorrow but I'd like to have a plan when I get out there.
Until then I'll be rebuilding my girlfriends tranny on her coffee table. Hope she doesn't come home.
Thread Starter
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Tuned
Joined: Jul 2011
Posts: 350
Likes: 3
From: Sacramento, CA
A) Power Valve??? What's that?
B) 600-650 RPMs sounds good to me but I read that with the automatic transmission is it really wants to be set closer to 500.... Did I read wrong? I also thought that the racing cam might make it idle a little higher.
But once again I really don't know enough to know what an aftermarket can might or might not do....
Thanks for putting up with me
Joel
B) 600-650 RPMs sounds good to me but I read that with the automatic transmission is it really wants to be set closer to 500.... Did I read wrong? I also thought that the racing cam might make it idle a little higher.
But once again I really don't know enough to know what an aftermarket can might or might not do....
Thanks for putting up with me
Joel
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Posting Guru
Joined: Mar 2006
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What kind of carburetor are you running?
Generally speaking- the power valve is a spring-operated diaphragm. once engine vacuum drops below a certain point (ie- when you've got your foot in it), the valve opens and dumps extra fuel.
so- if the diaphragm is blown, it can leak extra fuel into the carb 24/7, thereby keeping you from being able to regulate engine idle via the idle mixture screws.
love the picture- i'd have to sleep in the yard if i pulled something like that.
Generally speaking- the power valve is a spring-operated diaphragm. once engine vacuum drops below a certain point (ie- when you've got your foot in it), the valve opens and dumps extra fuel.
so- if the diaphragm is blown, it can leak extra fuel into the carb 24/7, thereby keeping you from being able to regulate engine idle via the idle mixture screws.
love the picture- i'd have to sleep in the yard if i pulled something like that.
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Posting Guru
Joined: Mar 2006
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or you can buy a Holley valve...they make them with different springs, so can match them to your particular setup.
meaning- if you're running a stock-type cam with high vacuum, you might use a power valve that kicks in at 9" of vacuum.
if you're using a lopey cam with low idle...you'll want a lower number.
hard to say without knowing what carb you're using.
Thread Starter
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Tuned
Joined: Jul 2011
Posts: 350
Likes: 3
From: Sacramento, CA
I'm running a recently remanufactured Motorcraft / Autoline (that I'm guessing is a 2100) it was put on by the PO about two months ago. He kept putting on new parts trying to get the truck to run but didn't tune anything. I.e. new carb but air mixture screws turned so far out that the left one was only holding on by one thread and new distributor cap, points but retarded AFTER top dead center 4 degrees. Etc... Explains why I got the truck for a song.
I pulled up a diagram of a Motorcraft and it looks like I've got to pull off the carb to check the power valve. Is that correct' it's on the bottom side?
As for picture, when she met me, I had for motorcycles in my living room,, three were restored but I was working on one (which later became her first bike)
It's still raining so I may not get out today...
Also, looks like somebody got under the truck last night and cut some wires. I think I had my rear sending unit stolen...
I pulled up a diagram of a Motorcraft and it looks like I've got to pull off the carb to check the power valve. Is that correct' it's on the bottom side?
As for picture, when she met me, I had for motorcycles in my living room,, three were restored but I was working on one (which later became her first bike)
It's still raining so I may not get out today...
Also, looks like somebody got under the truck last night and cut some wires. I think I had my rear sending unit stolen...
Posting Guru
Joined: Mar 2006
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yes- on the bottom.
before you pull the carb, try this-
start the truck. turn both idle screws all the way in (be gentle, no need to crank them down).
if that doesn't kill the engine, something's wrong with the power valve.
before you pull the carb, try this-
start the truck. turn both idle screws all the way in (be gentle, no need to crank them down).
if that doesn't kill the engine, something's wrong with the power valve.
Thread Starter
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Tuned
Joined: Jul 2011
Posts: 350
Likes: 3
From: Sacramento, CA
Got the timing 12 advanced. Vacuum is pretty steady at 19.5 with a slight vibration, advancing the timing anymore makes my valves sound like they are rattling. Ting ting ting ting...
And I figured out the idle problem. The throttle cable is to short. The PO had it zip tide together on the peddle side. Just can't get it long enough to bottom out on the idle screw. So I need the correct throttle cable.
Joel
And I figured out the idle problem. The throttle cable is to short. The PO had it zip tide together on the peddle side. Just can't get it long enough to bottom out on the idle screw. So I need the correct throttle cable.
Joel