timing adjustment
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timing adjustment
Can't get my idle below 1800 without it stalling, so figured I'd check the timing, and it was advanced 30degrees. Now i realize it will go up some when the idle is up, but will it go up that much? and if so, is it possible to dial it back that far my rotating the distributor when I adjust the timing???
This is a 78 F-150 with 50K on a rebuilt engine. Just rebuilt the carb and trying to tune it and no luck getting it to idle below 1800 so far. Don't see any vac leaks and even checked it with a gauge.
This is a 78 F-150 with 50K on a rebuilt engine. Just rebuilt the carb and trying to tune it and no luck getting it to idle below 1800 so far. Don't see any vac leaks and even checked it with a gauge.
Post Fiend
Joined: Apr 2008
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From: Big Sky Country
The fact that you just rebuilt your carb would lead me to believe something is a miss there, i'm assuming you didn't mess with your timing during the carb rebuild, 30 degrees of advance @1,800 rpm's is nothing to be alarmed about because at 1,800 rpm's you're also reading vacuum and centrifugal advance as well as initial.
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Hey guys, thanks for the quick responses. First the vac advance is connected to manifold vacuum and yes, I did have it disconnected from the distributor when I checked the timing. I also capped off the advance vacuum port on the distributor.
Also, I had the gauge connected to the port on the vac advance and it showed no vacuum. I was using the hose that is normally connected to the vac advance, and noticed that there was a metal sleeve on the vac advance side.
If the vac advance was disconnected then I shouldn't have been seeing 30 degrees of advance should I????
Also, I had the gauge connected to the port on the vac advance and it showed no vacuum. I was using the hose that is normally connected to the vac advance, and noticed that there was a metal sleeve on the vac advance side.
If the vac advance was disconnected then I shouldn't have been seeing 30 degrees of advance should I????
Post Fiend
Joined: Apr 2008
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From: Big Sky Country
Keep in mind you're reading this with the engine idling at 1,800 rpm's, so it depends where your initial is set and how your distributer is curved, most stock distributers have all their advance in well before 3,000 rpm, so if your total advance is 36-38 degrees and all in around the 2,500 to 3,000 rpm range then 30 degrees of advance @1,800 rpm is to be expected.
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ok, that makes sense, thanks for explaining it. Mine has a total advance of 30 degrees, and it was hovering between that and 'BTC'.
Darn!
I was hoping I could dial that back and fix my idle problem. But I think you're right about my rebuilt carb, I just didn't want to admit defeat so easily...wouldn't believe the hassle it was to rebuild that thing. Guess I gotta go figure out who in VA gets my money to rebuild the carb.
Darn!
I was hoping I could dial that back and fix my idle problem. But I think you're right about my rebuilt carb, I just didn't want to admit defeat so easily...wouldn't believe the hassle it was to rebuild that thing. Guess I gotta go figure out who in VA gets my money to rebuild the carb.
Certified Thread Hijacker
Joined: Aug 2001
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You want PORTED vacuum from the carb and not MANIFOLD vacuum from the intake for the Vacuum Advance on the distributor.
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Postmaster
Joined: Aug 2005
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From: Gadsden Purchase
Whenever the gang would work on my district I could count on some overtime! :)
It's just the way it is, even if the fault couldn't be directly related to the guys working on it, them just out there messing with stuff could disturb something that was working, but maybe -just barely- but was working.
Could you tell us which model carburetor you're working on?
I've always been into carburetors and modifying them is an interest of mine. :)
Alvin in AZ
It's just the way it is, even if the fault couldn't be directly related to the guys working on it, them just out there messing with stuff could disturb something that was working, but maybe -just barely- but was working.
Could you tell us which model carburetor you're working on?
I've always been into carburetors and modifying them is an interest of mine. :)
Alvin in AZ
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ported vac from the carb? There is only one vacuum connection coming off the rear of the 2150 carb, and it's connected to a tree vacuum connection on the rear of the manifold. It was that way when I got the truck, but I'll check it out tomorrow night.
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