Classic/Antique Car Repair: 1966 GTO 389, tri power, 4 speed, starter fluid, rocker arms

Question
QUESTION: Good afternoon. Help! The is a stock non-modified car. I was accelerating to 4,000 RPM or so and the engine stopped and vibrated. I coasted to a stop. When you try to start the engine it sounds OK. I am getting spark to the plugs and gas to the carbs. I checked the compression and it is OK in all cylinders. It is 160 in 2 cylinders and the range is 170 to 185. I removed a valve cover and the rocker arms are doing their thing.
What should I check next?
Thanks so much for your help.
Dave

ANSWER: How many miles on the engine? let me know.

---------- FOLLOW-UP ----------

QUESTION: The odometer indicates 75,000 but who knows if it is accurate. I rebuilt the heads last year so I believe the valves, springs, and rocker arms are good. I tried using starter fluid directly into the carbs and got nothing.
Dave

Answer
At this mileage I would suspect a jumped timing chain. To check the chain without removing the front cover rotate the engine with a wrench on the front pulley in the proper direction. With the valve covers off put one finder on the intake rocker arm for number one cylinder and and other finger on the exhaust valve. Slowly rotate the engine until the exhaust vale is just closing and the intake is just opening and they are both open an equal amount. If you are handy with a dial indicator you can use that instead of your fingers. At that point the timing mark should be within a few degrees of TDC. If it is not the chain has jumped a few teeth and needs to be replaced. Then remove the distributor cap Note the position of the rotor and the points. The point should be just barely open and the rotor pointing to number 8 plug wire. Now mark the front pulley and with the wrench turn the engine in the opposite direction until the rotor just starts to move. Note the mark on the front pulley and if it has move more than 3/4 of an inch the timing chain is worn and needs replacement. Let me know and if this is not the problem we will go from there.