Classic/Antique Car Repair: 1970 Olds Cutlass Supreme, olds cutlass supreme, 1970 olds cutlass


Question
QUESTION: I was wondering what the fast idle, curb idle, and base idle should be set to for a 350 V8 with a 2 barrel carb. The chiltons manual says 575 rpms but that sounds kind of low.

ANSWER: Hi Matthew:
I know that sounds low compared to my car and others, but Olds built some very powerful engines back in the day. Actually the Tune-Up specification for that car is 850 for a manual shift and 550 for an automatic. It's almost like tuning a Harley. Doesn't take much gas for her to idle. My Chevy 305 idles a bit high until really warm. Then she comes down to around 900. Most new cars today idle at 1500 to 2000 rpm, because of much smaller engines. That's why there is no longer a huge different between city mpg and highway mpg on new cars. Hope this helps.

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QUESTION: I would like to know what the difference is between curb idle and base idle?

Answer
Hi Matthew:
Set the high idle speed between 1200 and 1500 RPMs. However, Once you have set the base idle, the automatic choke should revive up to around this anyway. So set the base and start her cold and she how she idles during warm up.


The curb idle (e.g. base idle) are the same. Curb idle is just another term for base idle. The curb idle screw adjusts the idle speed when the vehicle is warmed up.