exhaust backfire at idle

[356robo]

Before service, no backfire.

After adjusting valves, installing pertronix, setting timing at 2 degrees btc at 900 idle and 30 degrees at 6,000, installing new plugs, I now have periodic backfire through the exhaust at idle.

The webers were not touched. The exhaust was not touched.

Anyone have any ideas?

Thanks in advance,

Rob

[66S]

Sounds like a plugged or lean idle jet.

[chiroracer]

the idle air screws probably need to be dialed, sometimes I can do this on my own (memorize slot positions before you touch it) and sometimes I take it to jeff at randall aase.Steve

[356robo]

66S and Steve,

Thank you for your responses, but I don't think its a carb issue. I did not touch the carbs.

All I did was:

Adjust valves
Replace plugs
Install Pertronix
Set timing at 2 degress after tdc @ idle and 30 degrees @ 6,000 rpm

Today, I'll check all wiring connections and make sure cap and rotor are aligned properly.

Rob

[356robo]

I found it. A couple of plug wires were loose at the distributor, duh.

Checked all of the connections, warmed her up and went for a drive.

There's nothing like the sound and feel of a freshly tuned 911.

Rob