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I’m having a slight shake at idle on my 81. It levels out at speed but the shake is notable while idling. I just changed plugs and #5 was not very tight. Attached is a picture of them and the one with the fouled white was the loose one.
I tried to have it timed today as well and there is no mark that is noticeable. The mechanic thinks my distributor might be dropped in wrong. That would explain the rough idle I believe.
I think the distributor needs to come right out and dropped in the correct position.
I really doubt the dizzy needs to be re-stabbed if the engine runs good past idle. If its off one tooth you would know it through the entire RPM range.
Put the balancer at TDC by jogging the IGN key. Pull the cap and note where the rotor is pointing. Number one?
I would clean and reinstall all the plugs. They all look to be running hot though.
Cylinders 5 & 7 plug cables must be as far from each other as possible. Those two, due to the firing order may experience Inductive Cross-fire. Separate them on the wire looms.
You might have a vacuum leak somewhere causing a lean condition. Perhaps the fuel mixture screws need a tweak.
If you are convinced the dizzy is off one tooth, its much easier to move all the plug wires around on the cap, one at a time than to align the oil-pump shaft.
Last edited by HeadsU.P.; Jul 30, 2021 at 07:40 PM.
I'm not convinced its a timing issue. Just trying to figure out the idle. I put all new plugs in today. It does not run rough through the RPM's, just when I put it in park, it's not really that bad when idling in D. Also, it is not a CCC car anymore, it has a non CCC Rochester carb and vacuum advance distributor.
Exactly what does no mark visible mean?
Is there a timing tab visible on the timing cover when looking from the driver's side?
Is there a timing groove on the damper ?
Did the mechanic disconnect the vacuum advance?
Have you checked if the four bolts holding the carburetor down are loose causing a vacuum leak?
Have you any issues with the headlight vacuum system that would indicate a leak?
I find the passenger side easier. No steering box or dipstick. But I have headers, no plug shields, etc.
The rough idle issue sounds like carb issues. Why the timing mark is not showing up? Not sure yet.
I think I would pull the dizzy cap and grab the rotor. Make sure it snaps back to return position easily.
He couldn't see the timing mark on the HB. Yes the vacuum advance was disconnected, I was standing there plugging it myself. I actually haven't tried to tighten the carb bolts, never thought of that. And yes the headlights work perfectly fine, the drivers side comes up about a second slower than the passenger if that makes a difference.
I tried to time it myself with a light but since i am just a Bubba i didn't want to get too crazy. When I looked at the timing, at about 2500 rpm the timing mark on the HB was about 3" below the timing tab. I'm not exactly sure what the problem was today. I had marked the notch on the HB with bright yellow paint when I looked at the timing.
I find the passenger side easier. No steering box or dipstick. But I have headers, no plug shields, etc.
The rough idle issue sounds like carb issues. Why the timing mark is not showing up? Not sure yet.
I think I would pull the dizzy cap and grab the rotor. Make sure it snaps back to return position easily.
My 81 has the dipstick on the passenger side and ALL the smog crap... Made for a tricky job..
Carefully turn the idle mixture screws clockwise, counting the exact number of turns for each, until they seat. Don't 'tighten' them, just seat them; let's see what they are....
Counting the number of turns is so that you can return them to where they were. Just want to see if they are like, set way different or something like that.
Last edited by kansas123; Jul 30, 2021 at 08:57 PM.
Carefully turn the idle mixture screws clockwise, counting the exact number of turns for each, until they seat. Don't 'tighten' them, just seat them; let's see what they are....
I need to get a flexible screwdiver. Mine are so far in I can't get at them.
Smells rich at idle is fairly normal. It really does sound like balancer has shifted. I am a mechanic. I would be checking the timing mark with a piston stop in the number one cylinder. But it really sounds like a new balancer is in your future. get one with timing marks out to 60 degrees. You'll thank me later.
Is this a recent problem?
Did it run better in the past?
If so, timing is probably not the problem.
New plugs are a good start. Next are the other ignition parts--plug wires, dist. cap, etc.
I recently got my idle to smooth out by running a can of SeaFoam through my gas tank. A noticeable improvement.
Help me understand how the orientation of where the distributor is "stabbed" can have any actual effect on how the engine runs as long as it timed correctly with a timing gun and the wires are in the correct firing order?
Spark Plug Condition
