Hot Rod Trix
Thread Starter
Racer
Joined: Oct 2007
Posts: 284
Likes: 6
From: Palm PA
Hot Rod Trix
Does anybody have any "Hot Rod Tricks" to smooth a rough idle? My old 350 had a hyd. cam with a 268 degree duration cam that worked good. When I built a 383 I put in a 270 degree hyd. roller cam. I have 17 to 18" of vacuum, it fluctuates at idle. The 383 runs great at anything above idle. If my foot is off the gas I usually have the clutch in to stop the "bucking". I can live with the car as is or am I overlooking something simple?
Thanks
68 Vetteman
Thanks
68 Vetteman
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
17 to 18 inches of vacuum at idle is a lot. You should not habe any problems with that much idle. I was running about 8 inches on my 383 build and it idled and ran fine. Tune the carb idle. You really need to hook up an AF gauge to see if you are lean or rich. That is a lot of vacuum and a mild cam for a 383 motor.
Thread Starter
Racer
Joined: Oct 2007
Posts: 284
Likes: 6
From: Palm PA
17 to 18 inches of vacuum at idle is a lot. You should not habe any problems with that much idle. I was running about 8 inches on my 383 build and it idled and ran fine. Tune the carb idle. You really need to hook up an AF gauge to see if you are lean or rich. That is a lot of vacuum and a mild cam for a 383 motor.
I've never used an AF gage. Do they sample the exhaust gas with a probe? I determined the holley 700 dbl pumper carb was lean by reading the spark plugs and went from a 68 jet to a 70. I might throw the old carb on and see if it helps.
68 Vetteman
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
The actual jets will do very little if anything for the idle. The idle mixture screws are for that. The jets are full full throttle operation and somewhat for cruise mixture.
Yes an AF gauge does sample the air and gives yo ua readout as to the mixture. I have an Innovate Af gauge and when I was running a carb i thought I was pretty close but was off. It gives yo ua readout at all operating conditions. I had a bung welded into my collector which is best but you can also do it with the probe.
Yes an AF gauge does sample the air and gives yo ua readout as to the mixture. I have an Innovate Af gauge and when I was running a carb i thought I was pretty close but was off. It gives yo ua readout at all operating conditions. I had a bung welded into my collector which is best but you can also do it with the probe.
Thread Starter
Racer
Joined: Oct 2007
Posts: 284
Likes: 6
From: Palm PA
The actual jets will do very little if anything for the idle. The idle mixture screws are for that. The jets are full full throttle operation and somewhat for cruise mixture.
Yes an AF gauge does sample the air and gives yo ua readout as to the mixture. I have an Innovate Af gauge and when I was running a carb i thought I was pretty close but was off. It gives yo ua readout at all operating conditions. I had a bung welded into my collector which is best but you can also do it with the probe.
Yes an AF gauge does sample the air and gives yo ua readout as to the mixture. I have an Innovate Af gauge and when I was running a carb i thought I was pretty close but was off. It gives yo ua readout at all operating conditions. I had a bung welded into my collector which is best but you can also do it with the probe.
68 Vetteman
