ChrisM

I have just rebuilt my rochester 2 barrel carb. What should my idle speed be for a 1973 delta 88 350 with a 2 barrel rochester carb? The Haynes manual doesn't have it, so it would help if anyone here knows...

Thanks everyone. I could not do any of the stuff I've tried without you all.

Thanks in advance,
Chris

ChrisM

Bump
Any help would be great here guys...I really don't know where else to find the idle rpm info....
Joe P.?

joe_padavano

I'm afraid I don't have a 73 CSM, but the idle speed should be on the emissions sticker on the radiator top plate, if it's still legible. Failing that, 675-700 RPM in drive is a good place to start.

OLD SKL 69

x2

ChrisM

Thanks guys. That should help. Unfortunately the previous owner thought it would be a good idea to remove all of the engine stickers, so I don't have that resource. I will set the idle to 675 and see how it runs. The exhaust is smelling really rich, so I will adjust the mixture idle mixture screws after the idle speed. This should help with the rich mixture, correct? My understanding from the haynes book is screw in the screws until I am losing idle rpm, then back them out slowly until I reach my idle speed and now further. Correct?

Thanks again everyone. I would never have even attempted the carb rebuild without all of your encouragement, and now I have completed that and have the car running again. I never thought it would all go back together.

Chris

joe_padavano

Unfortunately, the idle mixture screw adjustment and idle speed adjustment are an iterative process. I usually back the idle screws out three full turns from fully seated to start. I then use a vacuum gauge and adjust to maximize the vac reading at idle. Depending on the car, I may shoot for the lean side of the adjustment, since there will be about a half turn or so where it really doesn't change the vac reading very much. Once that's set, go back and set the idle speed. Now you may need to recheck the idle screw setting, etc, etc. Usually two passes gets it nailed.

ChrisM

Thanks Joe. I will try that. One question: Do I set the idle speed at the idle solenoid with the transmission in drive? I have an automatic transmission and I thought I read somewhere that I need to set the idle speed on the solenoid with the car in drive. Sound familiar? Thanks again for always answering all of my amateur questions. It helps to know that someone as experienced as you is watching... Thanks.
Chris

joe_padavano

It depends on how that solenoid is operated. Some are anti-diesel solenoids that are activated whenever the engine is running to hold idle speed then retract when the engine is shut off to close the throttle further and prevent dieseling. Others (notably the VIN 9 307s) use the solenoid to increase idle speed under load from the A/C, but it is normally retracted under regular idle conditions.

I suspect you have the first type, but whether or not you set the idle speed at the solenoid is a function of which type you have. Hopefully someone with a 1973 CSM will chime in here. (hint, hint)