There is no vacuum advance on the engines in the larger trucks. It sounds like your carb. is lean or the timing is real slow.
I quick test on for an exhaust restriction is to stand in back of the tail pipe. Have someone rev the engine up & let up on it. If it makes a hissing noise out the pipe it is probably restricted. If it has a nice rumble at idle it probably is ok.
Try advancing the timing some & see if it improves anything. You probably can run the timing a few degrees more advanced then the specs show.
Its possible the governor is causing a problem. You might consider removing it but you would need to replace the carb & dist. to do so. It is not needed on light duty trucks.
OK I see that is not a small light duty truck. You may want to keep the governor on it.
Last edited by Wrenchbender Ret.; 10/25/2024 2:47 AM. Reason: Not paying attention
