Idling Issues
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Mountain Pass
Joined: Mar 2006
Posts: 145
Likes: 2
Idling Issues
I am trying to get the timing and carb adjusted on my 54 239 ohv. There is only one mark on the damper and I was wondering if that's the only mark you line up the pointer on when you put the timing light on it. Also I noticed no matter how I move dist when running when I give it gas it hesitates real bad at first then levels out. Also when I pull the vac line off the back off carb to plug to set timing I feel no suction at all from the hose.
Fleet Owner
Joined: Jul 2004
Posts: 27,295
Likes: 1,056
From: NM
There is almost no vacuum in that line at idle. It's not manifold vacuum.
If the early Y-blocks are like flatheads, ye, you just line up the bump on the crank pulley with the pointer.
Have you watched the timing when you blip the throttle? The timing should advance.
If the early Y-blocks are like flatheads, ye, you just line up the bump on the crank pulley with the pointer.
Have you watched the timing when you blip the throttle? The timing should advance.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Theoretically engine timing could be set at idle spec without disconnecting/plugging vacuum advance hose. It's kind of a "belt and suspenders" thing. It simply removes any possible variables from the equation, such as a vac hose hooked to the manifold port, or idle set too high, etc.
You can observe the limits of mechanical advance with a light at 2500 RPM say, then reconnect vac hose and see how much additional timing the vacuum advance brings in on top of that.
Set idle to specified RPM. Put the timing light away for now. Then set timing with a vacuum gauge - usually about 1" of vacuum below the max manifold reading is pretty close to perfect. Set idle to spec again. Set idle mixture, and finally, reset idle. Check for ping or detonation on highway and acceleration, back off a little more if necessary. This works slick.
You can observe the limits of mechanical advance with a light at 2500 RPM say, then reconnect vac hose and see how much additional timing the vacuum advance brings in on top of that.
Set idle to specified RPM. Put the timing light away for now. Then set timing with a vacuum gauge - usually about 1" of vacuum below the max manifold reading is pretty close to perfect. Set idle to spec again. Set idle mixture, and finally, reset idle. Check for ping or detonation on highway and acceleration, back off a little more if necessary. This works slick.
Fleet Owner
Joined: Jul 2004
Posts: 27,295
Likes: 1,056
From: NM
That won't work with a Load-A-Matic, it's 100% vacuum-controlled advance.
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