[ric2604]

Hi All,
I have a stock 1984 El Camino with all emissions and factory CCC carb. Since I had the truck about 6 months, I noticed a rough idle when warm. Here are thing things that I have done to help remedy the problem:

Replaced ignition wires, some wires looked like they were rubbing against metal, so I replaced and re-routed for no contact.

Checked vacuum lines, found a couple bad lines and replaced with new lines
(This helped the problem, still rough though)

Checked Carb mounts, found that were pretty loose, so I tightened the mounts (not too much to warp the mount) seemed to be a minor improvement.

Replaced Catalytic converter
(much better running, had original on there, better idle quality and take off power)

I decided to check the mixture, and purchased a d-type screwdriver. Here's how I was able to get the idle to perform better:

Screwed in mixtures and had the turns out about 2.5 turns each side. Restarted engine and advanced each mixture screw about another turn each (I'm about 3.5 turns out on each). Engine still had a occasional lope (misfire). I then turned the idle bleed screw about 1/4 turn clockwise, that seemed to smooth out the idle nicely.

So far the idle is much better, normal. No check engine (didn't have one before either, but likes up on start up check). I'm concerned that I might be now running a little too rich and could damage the Cat? Any ideas? I figure if something is found out of range the check engine light would record a code.

Before I did any idle or idle air bleed adjustments, I noticed that the engine speed would pick up if I covered my hand over the air inlet on the air cleaner. After the mix adjustments it doesn't seem to do that.

Any help or feedback is greatly appreciated. Thanks!

 

[BOOSTED-SS-ELKY]

The fact that the engine rpm's would rise when you covered the air inlet is consistant with the fact that it doesnt do it anymore now that you have turned the mixture screws out another turn (It was too lean).

Adjusting the idle mixture screws by ear is one way to do it, but if you want to do it the correct way then hook up a vacum gauge to the base of the carb and adjust for the highest vacum reading. Now, this would be the last thing you would do after you verify the timing is correct and set the idle. Changing the timing is going to increase and decrease the engine's idle rpm. I don't know where your timing is set, but you could probably advance it a degree or two, re-adjust your mixture screws, adjust your idle and get the engine to idle a lot smoother.

 

[ric2604]

Thanks 1320ElkySS
I definitely need to reset my idle, now it idles too high. I do have a portable tach so I'll set the idle back down. What I suspect happened is that the previous owner opened up the air bleed to pass smog, I found that the canister purge "thing" was leaking raw gas into the carb. To re-pass emissions when I bought the truck the canister purge item was replaces soon after I had a rough idle.
My timing is at 8 deg btdc, which was within the +/- 2 deg from 6 deg base setting on the label. The smog guy was going to retard it back to 6 and I told him to leave it alone.:yell:

I love tinkering and making small improvements and learning as I go. Thanks again for your help.

 

[BOOSTED-SS-ELKY]

Thanks 1320ElkySS
I definitely need to reset my idle, now it idles too high. I do have a portable tach so I'll set the idle back down. What I suspect happened is that the previous owner opened up the air bleed to pass smog, I found that the canister purge "thing" was leaking raw gas into the carb. To re-pass emissions when I bought the truck the canister purge item was replaces soon after I had a rough idle.
My timing is at 8 deg btdc, which was within the +/- 2 deg from 6 deg base setting on the label. The smog guy was going to retard it back to 6 and I told him to leave it alone.:yell:

I love tinkering and making small improvements and learning as I go. Thanks again for your help.

No Problem :beer: