Carb Tuning

You will need more intial timing and will likely have to do something to limit the timing on top.

I am running an XE268H in a 360 with 10.6:1 compression and magnum heads. I run 15 degrees initial and 33 total (magnum heads require less than the open chamber LA heads), it is all in at 2500 rpm. I run 89 octane gas in this engine and have no detonation issues.

The throttle response is instant and the engine pulls strong from 1500 rpm. The idle is almost as smooth as a stocker.

The XE268H is more agressive in a 318 than a 360 but you should be able to get a resonably smooth idle even in a 318.