Idle issues

So, my '83 El Camino has been having some issues at idle when cold. It will start and immediately start acting like two cylinders that are next to each other in the firing order are not firing. It sounds like it fires normally, then a BIG dead spot, then it fires normally for another cycle.

I dialed my electric choke back 4(!) notches leaner and it helped but still does it. I also switch the vacuum advance to ported vacuum and it went away completely, but feels down on power and there is bogging issues when it is hooked up like this.

The engine is a 350 with a mild cam and an Edelbrock 1406 carb.

Any ideas on this one?

Jim hopper said:

Yeah get rid of that Edelbrock junk my buddy had the same problem with his he put a Holley on it probably went away

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Oh trust me I would love to, but since all my car money has been going towards the Bonneville, the El Camino may have to deal with it a while longer.

pontiacgp said:

your vacuum advance should not be getting any vacuum when the engine is cold. I would check the timing, make sure there is no vacuum advance when setting the timing

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My distributor gets full manifold vacuum normally, and was originally timed as such. I only switched to ported for testing purposes, and would much rather leave it on manifold as vortec heads tend to crack if they get hot.

My initial timing is currently at 12 degrees BTDC but it seems like it gets in a loop where when it lopes real bad, the vacuum surges and advances timing. Once it hits that dead spot the vacuum drops off and retards timing, and the thing starts firing again for another cycle. The distributor is only a couple of months old, and is rock steady under a timing light.

The carburetor has been on the to-do list for a while now for getting a rebuild kit put in but it hasn't happened yet. It seems to run fine most of the time, but occasionally leaks externally.