I want to try a carb spacer on my 360 with RPM air gap and AFB carb. What jetting change is required to run a 4-hole, or 1-hole spacer?

Thanks guys

Dennis Jokela

There are no set rules for this type of change. This is a typical example of having to try it out and seeing how it responds to small jetting changes in both directions.

If I install either type of spacer, the car slows down a couple of 10ths.The only thing I can figure,is that I need to richen it up some.

Dennis Jokela

It also depends on how you are jetted originally!

Installing an open spacer can theoretically require more jetting because of more intake volume and less signal to the carb. However, if you are jetted optimally or a little lean, the car can slow down. If you are jetted rich to begin with, it can pick up!

Same thing with the accellerator pump circuit for the same reasons.

Jet for MPH and experiment with pump cams and squirters for 60' times. Sometimes a rich accellerator pump shot can partially mask lean jetting and rich jetting can mask a lean pump circuit. It ain't always easy.