Oliver 77 mis-firing

[MachinistNick]

Hi folks, I've got an early model 77 (s/n 271721C77E) that I'm rebuilding with the intention of selling.
So far I've replaced the coil, points, rotor, cap, and plug wires. I'll replace the plugs, just haven't got to it yet.
The problem is the back half of the engine does nothing. (Cylinders 6,5,& 4)

The valves don't appear to be stuck, but might be a bit close (around .006 rocker clearance )
I'm sorta leaning towards either the valves need reseating, or the head gasket is toast.

Has anyone dealt with a similar problem? What sort of solution would you suggest?
Thanks,
Nick.

 

[J. Schwiebert]

Valve clearance is 010 & 017. Have you checked compression?

 

[MachinistNick]

Sorry, not sure how to edit.
Its .006 on intake and around .015 on exhaust.

 

[MachinistNick]

Just with my thumb (!)
It seems to bark pretty nice on all of them.
Going into town later to get plugs and a comp tester

 

[MachinistNick]

Thanks J.Schwiebert!
Set the valves, runs like a top!
Also threw in new plugs, but I doubt that was the problem.