Excessive high idle on cold start with an Edelbrock 1406

[JanZverina]

  Hoping for some clues. Yesterday I started up by '63 Riv, which was not started in a month - my bad. I had a new Edelbrock 1406 installed on it in late 2019 and it always ran very well, worlds better than a wonky 4GC which was  beyond a rebuild if anyone remember my earlier thread. (The rebuilder was kind enough to give me a full refund.)

  I understand that with the 1406, one should press the gas pedal once with the electric choke, but I had to press the pedal numerous times for it to start, and when it finally did, it immediately idled excessively fast, and if I pressed the gas pedal slightly it would stay at the higher rpm.. Not sure what happened, but after shutting down quickly and manually pulling the throttle linkage back a bit and lowering the idle screw quite a bit I managed to get it to start at a lower idle on choke, but before long (it's about 96 degrees here in San Diego this weekend) the engine started running off the choke and at a fairly normal rpm. This morning after a full cool-down I tried to restart and same thing, a very high idle at startup.

  I went on the Edelbrock site and it said to make sure there's no air getting in the carb via an open port. There's a screwed-in metal plug at the center rear (power brake port). There's a tight connection to the PCV port up front center, a good hose on the 3/16 vacuum advance port on passenger side, and a tight cap on the 3/16 manifold vacuum port on the driver's side. I also see there's a fast idle screw below the idle screw but I can't imagine how that would get out of adjustment so fast. The large throttle linkage spring is in place and everything looks to be connected according to the shop manual.

  Any ideas welcome!

 

 

     

[Jim Cannon]

The fast idle screw will not get out of adjustment. Look for binding in the fast idle cam linkage and in the choke linkage in general.

 

Normally when the engine starts, vacuum pulls the choke open and pulls you down off of the high-speed portion of the fast idle cam. It sounds like your choke mechanism, due to sitting for a while, is not pulling off properly after you start it and tap the gas. Look for sticky linkages or shafts. Look at the little piston inside the choke assembly for some junk making it stick.

 

 

[JanZverina]

Many thanks, Jim. I think you gave me enough guidance to sleuth through this. After studying the Edelbrock 1406 pdf a bit closer, it looks like the fast idle cam was in the wrong position, and just for good measure I inspected the choke assembly more closely. It started right up normally after some minor adjustments but I'll do another "cold" start tomorrow here in 80s+ San Diego. I know, we're spoiled. But this weekend we've been getting a special dose of airborne ash from the LA-area wildfires!

 

[first64riv]

I'm up in Temecula (live in San Diego up until two years ago) and we had ash on our cars this morning.  I need to get my car out but it's been way too hot.

 

I'm glad you got your issue sorted.  I have the Edelbrock 1411 and I had some issues last week.  It turned out I didn't let it fast idle long enough for it to warm up fully.  Choke closed up and I couldn't get it started until I manually opened the choke back up.  We are definitely spoiled by this "cold" start weather.

 

Chris

[JanZverina]

Thanks, Chris,

I'm in University City close to UC San Diego, where I used to go to work before COVID, but I'm now working from home like a lot of other folks who were fortunate to keep getting a paycheck. And of course one seems to work more hours from home! I'm not driving my daily ride or classics nearly enough these days so I think that's what got me in trouble this time around. Especially the Riv - my maintenance sked is based more on time gone by than miles piling up, that's for sure.

 

[first64riv]

1 hour ago, JanZverina said:

Thanks, Chris,

I'm in University City close to UC San Diego, where I used to go to work before COVID, but I'm now working from home like a lot of other folks who were fortunate to keep getting a paycheck. And of course one seems to work more hours from home! I'm not driving my daily ride or classics nearly enough these days so I think that's what got me in trouble this time around. Especially the Riv - my maintenance sked is based more on time gone by than miles piling up, that's for sure.

 

 

Man, I wish I had known you were in the area sooner.  I lived in Carmel Mountain but still work in Carlsbad.  So I'm doing the commute.  Fortunately, it's not as bad as Pre-COVID.  I hear you on the maintenance.  I have a log and it surprises me how much time goes by from one maintenance day to the next!