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Old 07-12-2018, 12:16 PM   #13
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Join Date: Jun 2018
Location: Marysville, WA
Posts: 28
Re: '70 K20 carb options

Originally Posted by 68 P.O.S. View Post
Its good you have an HEI. Its a great upgrade. Let us know what's weird about your HEI when you find out and we can help you sort it out.

If your truck is an automatic, your idle speed should be 600 rpm while in gear with your foot on the brake. In park you're looking at 750 to 800 rpm, no more than that.

Regardless of if you stay with a carb or go efi, its a great idea to replace your intake with a better unit. I personally recommend the Edelbrock EPS or RPM. And you should not have any timing issues related to replacing the intake.
The transmission is standard, old school. L-1-2-3-R.
So on the warm days when it runs crappy, it feels like it chugs until steady pressure on the pedal, and when in neutral at a stop it drops to the 800 RPM range and feels like it's gonna die.

On the good cooler days, it sits at 1K RPM's, unless I am driving for a decent distance, then it jumps to 1500 RPM's or a bit higher closer to 2K and if I hit the pedal it drops but not quite back down to 1K RPM's.

Not sure if the electric choke is borked which might be part of the problem.
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