[Bob 68327]

Originally Posted by vfrdude

OK - lets start at the beginning -

Set your timing at somthing like 4 degrees BTDC. Disconnect the the vacuum line to distributor and plug it (a golf tee works good).

Take the truck out, and do some full throttle acceleration runs. Listen for the pinging, if you don't hear the ping/knock, then advance the timing by another 2 degrees, and repeat. Do this until the motor starts to ping/knock, then back off the timing 2 degrees.

Now connect up the vacuum advance, take the truck out on a road where upi can cruise at about 50 MPH - accelerate from 50 to about 70 - not full throttle just use light throttle. You will probably hear the ping/knocking under light/part throttle at cruise.

You may have too much total advance for the enigine combo, or the vacuum advance is coming in too quickly. There are vacuum advance kits that will address both of these problems. I've used the Accel kit:
http://store.summitracing.com/partde...5&autoview=sku\

Hope this helps...

I Agree!!!