Cutting out over Bumps

Add a couple braided straps say from Transmission to chassis frame.  One of the current grounds is probably corroded where it connects to the metal frame. If it's not electrical could it be crap/water in the gas? 

Check the fuse box for corroded fuse holders or spades. Clean the contacts with a small wire brush (think harbor freight) with the battery cable disconnected . I had my tach start acting up and found the fuse box was the issue, over bumps it would cut out and fall to zero, then bump bump it was back working

This may seem way out there, but I seem to remember someone having similar issues, and the screw that holds the condenser on the side of the distributor was loose. Other than that, start checking wires and components for continuity. Al 

All great ideas regarding places to look at.  I can add a ground strap or two.  It is definitely electrical. It happens as the rear wheels make contact.

Thanks again

Do you have a pertronix ignitor in the distributor? Make sure the holdown screws are tight(use Loctite threadlocker) and also the base plate to the distributor body. Double check(pull hard) on all crimps and splices and terminals on the ignition circuit.

All very good places to look.

Also look at the starter (Behind the Rear Passenger-side wheel) to make sure the connections there are tight, too.  This is a spot that tends to be wheel-movement susceptible.  The connection at the starter often feeds the fuse panel directly, too.

Checked the three wires on the starter.  It appears to be a Pertronix, hold down screws are tight.  Added a ground strap from the side of the trans to the frame.

Checked the fuses, all tight.

wires on coil are fine.  I don't believe that any of the light grounds could cause a running problem.

i'll keep looking

In case someone else runs Ito the same issue, I found one of the fuse blocks loose.

i temporarily used a heavy tape to hold everything in place.  I will replace both fuse blocks when time permits.

CLOSURE

Thumbs up, Speeder!  Thx for taking the time to let others know about the fix.

Good to hear you found the problem!

Yeah....Root-Cause analysis is hardly ever easy, but you feel so good when you finally find something tangible!

Great job!