skipping slant six

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POPSKL04

Guest
74 225 ply duster, starts up and runs like a sewing machine until it gets warm and then will skip at idle. Seems to be Ok when running at higher rpms, has new plugs,wires points. also has all of the air pollution stuff. I believe all of the vacumm hoses are going to the proper places any ideas out there??
 
when you say a skip do you mean like a cylinder randomly drops and you get a pop in the exh or??

I bet your idle mix needs adjustment and even idle air bleed work.
 
I agree. Sounds electrical. BUT, since it's SO easy to run a compression test I would run one when it's hot. Just for elimination, and go from there.
 
Ballast resistor is less than a cup of overpriced coffee and you can change it while holding one. Wait, 74? Does it not have Electronic ignition??? If so, check reluctor gap.
 
My 69 Dart slant used to idle similar, driving me nuts for decades. Does it run rougher and slow down too much when shifted from P to R or D? If so, it is probably running lean at idle like mine was. The 4th Holley 1920 carb was the charm, then it ran like a dream.
 
Been reading a lot of post the last couple of days trying to figure out running issues. I started with a Vacuum gauge and looked at this site http://www.secondchancegarage.com/public/186.cfm. Found 2 problems right off the bat! Valves too tight and Timing was late. My idle is now smooth as glass and it responds off idle much better. Valve adjustment seems to be the biggest factor with idle quality on these engines. MUST be done while running! I was able to turn down my idle to 200 RPM and then just set to .010 Intake and .020 exhaust while running and smoothed right out.

Hope this helps

robert Voeltz "Voeltagear"

A-Body Enthusiast
 
Have you checked the valve lash while running. MUST be done while running. My 2cents.

Voeltagear
A-Body Enthusiast
 
BillGrissom said:
My 69 Dart slant used to idle similar, driving me nuts for decades. Does it run rougher and slow down too much when shifted from P to R or D? If so, it is probably running lean at idle like mine was. The 4th Holley 1920 carb was the charm, then it ran like a dream.
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yep, to large of idle air bleed. mine was .080" and needs to be .035"
 
You are right Moparkid it doesn't Need to be set While running. However "If" you have ever done while running then you know how much you lash "IS" off if you don't.
 
Voeltagear said:
You are right Moparkid it doesn't Need to be set While running. However "If" you have ever done while running then you know how much you lash "IS" off if you don't.
Click to expand...

lash is only off if you adjust the lash off the base circle, wrong feeler gauge thickness, or incorrect "feel" when using the feelers, running or not. also you have to remember on a big cam motor its not gonna idle below 800 or so making it really hard/impossible to do running.

i heat the car up, drive or cardboard infront of the rad, and get it to 210. then shut it off and let it heat soak for 30 mins, come back and start it and get it back to 200-210 and run the valves. i may lose 5* by the time i get the cover off but it still higher than operating temp so i know at the hottest temp they wont get tight.

ive tried running but never had luck with it, i just make two passes and go +/- .001 to make sure its where i want it.
 
If you have time for diagnostic start with vacuum readings and timing (both with and without vacuum advance hooked up. pay close attention to vacuum gauge when making any change as this will lead you in the right direction. There are many possibilities for a misfire ususally cause by incorrect air/fuel mixture, compression problems or timing errors. let us know what you find.
 
Hey you guys thanks for all of the ideas for my skipping problem. For more info, it does not have electronic ignition. Seems to be a "pop" in exhaust. always is the same cylinder i believe. waiting for the weather to cool off a little before I do anything. Getting to old to do to much wrenching anymore. starts real well hot or cold so i think timing is ok. I am thinking carb stuff. do get a smell of gasoline when sitting after a run. I think its the same carb that came with the car. Best place for a rebuilt is ????.
POPSKL04
 
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