1979 308 fast idle rpm

My '79 also has that issue. Very low idle when cold, but after a few minutes it's fine. Generally, I'll sit in the car and nurse the throttle for 2-3 minutes before I'll get out & let it warm up on it's own. I also don't think the butterfly assembly (choke) is working inside my air cleaner, even though I disassembled it, cleaned & reassembled it. I'll be following this thread.

 

The US ~3000 RPM cold idle spec was to meet cold-running emissions (and heat the cats up quickly) -- it is crazy. If you do use the cold idle cam to let more air in to the engine, you'll probably also have to use the choke to add fuel, too (and that also has risk) or set the mixtures very rich. Most of us just use/used the accelerator pedal to add more air and fuel (by some squirting) immediately after cold start up to keep it running, and then get on with driving gently ASAP (and again use the acc pedal, if necessary, when stationary until it isn't).

 

78 GTS US - Pertronix and richer jetting.
I set my cold idle, I live in So Calif so not so cold, at about 900 when its first started and the RPMs gradually increase to about 11 or 12 hundred as it warms up while driving then slows to about 1000 when fully hot. I use the cold idle cam to control the cold idle and very seldom use the choke. On 1st start of day I let the fuel pump run for about 5 seconds then pump it twice to set the cold idle cam and get some fuel into it then start it holding just a little throttle. It takes a little time (seconds) for it to settle down, four carbs after all, then can back it out and drive normally without "playing with the gas".
Since mine has richer jetting ,Pertronix ignition and coils, Accel plug wires, low resistance plug extenders, Iridium plugs and empty cats, along with 111 degree cam lobe centers (109 is stock) it may behave differently than yours.
Due to the Pertronix I run about 10 degrees more initial timing (no r2 retard points) which may also make a difference.
Idle RPM
Cold 1st start of day 900.
Hot without fans or AC on 1000
Hot with fans on 975
Hot with fans and AC on 940 of so.

Barry

 

The main advantage to the Pertronix, as I see it, is there is no messing with points, everything is one dizzy so there is consistent timing and advance curve for both banks and the super strong spark. Most users think they start and idle better. There also is no problem with point float at high RPM. Mine revs to the red line (a little above when I'm pushed) without ever missing a beat. When I had the points I had to use triple springs or it would misfire at very high RPM. Something else that is better on mine is that there is almost no "popping back" through the carbs when cold. Probably due to the advanced timing.
The primary disadvantage with the Pertronix, at least my setup, is having to advance the initial timing due to no "idle retard R2 points". I've had a hard time getting it to idle slow enough. Mine has the carbs completely closed and it still idles a little faster than I would like. I probably should put a longer advance curve in the dizzy so I could retard the timing at idle and still get to 34 degrees at 5K. The other disadvantage, for me at least, is possible module failure. It's never failed yet, about 7K miles, but we go on long hard drives and I'm a little concerned a module will fail a 100 miles from anywhere. I'm at worst going to get a spare module maybe even put a duplicate system in the other dizzy..
All in all I like the Pertronix setup and feel its worth the money.

Barry

 

My idle has always been just a tad over 1000. Sounds and feels right.