Fred: These old stovebolts are very dependable engines, provided all systems are functioning and in reasonal parameters of adjustment.
Since you stated in your post that you idled and/or slow speed operation for 2 hours before these problems arose, it would seem your ride is in fairly good running condition. Here are some things to check-
If engine is NOT overheated:
1. condition of plugs-regap or replace
2. point gap and adjustment-check/adjust/replace
3. fuel filter-replace, there cheap.
4. Float valve blocked,plugged, or float off adjustment. Open carb check set level. Check seat and needle
5. fuel delivery from pump, possible blockage or cracked pump diaphram-disconnect pump outlet, use coffee can and crank engine, check delivery
6. scale or crud blockage at fuel tank. Disconnect line at pump inlet. Backflush with air to tank. Make sure you remove tank fill cap.
If engine IS overheated, check:
1. heat riser valve stuck or spring broken
2. plugs/points
3. air cleaner restricted/dirty
4. exhaust restricted
5. water pump operation (belt adjusted)
More people will jump in on this soon!
Good Luck and think Chevy!
