RickDett

When rejetting a Q-Jet does proper jetting have an effect on reducing detonation?

bluedawg

I would assume so as proper air fuel ratio will help to a degree.

Kirk H

I would think the major concern, as Bluedawg pointed out, that if the air/fuel ratio is too lean, you will be running hotter than necessary which promotes detonation, as well as your compression ratio. If your ratio is over 10.25:1, you may have to take steps that were not necessary before when you could buy higher than 91 octane. I run just fine on 91 octane with this ratio without having to back off timing. In fact, I am running at about 10 degrees advanced when factory called for 4. When I was jetting my carb, I never ran into detonation at all.
I hope that helps in some way.

cagotzmann

Start by checking your timing.

1. Initial timing with vacuum disconnected from Distributor.
2. Total timing at 2500-3000 RPM

#2 should not exceed 36 degree's in most cases.

This will also allow you to check the mechanical advance is working correctly. It should change approx. 18 degree's from idle to about 2500-3000 RPM.

Once this is confirmed working correctly then worry about the carb.