Snapping sound under load.

[29spcoupe]

If you are not hearing the 'ping' with the spark fully retarded and you hear it when advancing, then the noise is spark related. The ping is not happening because of the compression ratio. Spark knock in higher compression engines occurs because the low octane gas ignites faster under high compression and therefore the adding of higher octane. If your timing is quite close with an ohm meter, is it possible that your distributor cam has moved a little causing the points to open sooner? My feeling is that it is timing. I would check everything again. I would like to hear what others think.

[SeaSlugs]

Originally Posted by 29spcoupe

If you are not hearing the 'ping' with the spark fully retarded and you hear it when advancing, then the noise is spark related. The ping is not happening because of the compression ratio. Spark knock in higher compression engines occurs because the low octane gas ignites faster under high compression and therefore the adding of higher octane. If your timing is quite close with an ohm meter, is it possible that your distributor cam has moved a little causing the points to open sooner? My feeling is that it is timing. I would check everything again. I would like to hear what others think.

I really dont know but going to sit and watch this as it unfolds and a solution is found. In regards to the timing it takes all of a wrench to reverse the timing pin, hand crank, and your eyeballs to see where rotor is pointing when the pin drops in. Deffinately cant hurt anything to check and check the point gap.