Engine lag

[1974Blueflame]

Not sure what’s wrong had to get it towed a while ago motor has a ticking sound and can has unusual shake now at idle and in drive. At idle while pressing throttle it just wants to lose power if anyone has had this problem before or any insight on what might be going wrong.
Timing, Plugs , ?

 

[SquareRoot]

@Ricko1966

 

[Cousin_Eddie]

Maybe a vacuum leak? My sons truck was doing the same thing. Vacuum hose was burned through (laying on the headers) as well as the brake booster rusted clean through on the bottom. Engine would shudder and die sometimes when you stepped on the brakes. Especially at idle.

 

[Truck82]

When I first put my engine together I misplaced a few vacuum lines and had quite a few leaks. My engine was doing exactly what you’re describing… shake, loss of power.
Another possibility for loss of power when you get into the throttle is you could be running a too rich fuel/air mixture. You can tell this by the black-ish color exhaust.
I definitely would check your timing also. That will give it a bad shake if it’s too far out.
I hope this helps some.
Good luck!

 

[Ricko1966]

Not sure what’s wrong had to get it towed a while ago motor has a ticking sound and can has unusual shake now at idle and in drive. At idle while pressing throttle it just wants to lose power if anyone has had this problem before or any insight on what might be going wrong.
Timing, Plugs , ?

If it developed a tick at the same time, my first suspicion is valve train. Poor man's power balance test take the girdle off the plug wires. Engine running grab a plug wire a couple of inches from the distributor cap,wiggle and pull up until the wire comes off,listen for the idle to change. Repeat until you find cylinders that make no change to idle. Test resistance on those plug wires,examine those plugs,run compression on those cylinders. If you have headers,which I'm assuming you don't. Instead of checking at the distributor you can wet a couple of fingers and just tap the headers by the ports,the cold cylinders are suspect. Both of these methods require a little common sense,so you don't get burned or shocked. You probably will get shocked a couple of times,it really doesn't hurt. Ignore this suggestion if you have a pace maker or medical condition that getting shocked might hurt you.

 

[TX87R10]

I had a bad alternator that was causing lurching randomly as the power surged. More noticable at night with the lights on.

 

[fast 99]

If it developed a tick at the same time, my first suspicion is valve train. Poor man's power balance test take the girdle off the plug wires. Engine running grab a plug wire a couple of inches from the distributor cap,wiggle and pull up until the wire comes off,listen for the idle to change. Repeat until you find cylinders that make no change to idle. Test resistance on those plug wires,examine those plugs,run compression on those cylinders. If you have headers,which I'm assuming you don't. Instead of checking at the distributor you can wet a couple of fingers and just tap the headers by the ports,the cold cylinders are suspect. Both of these methods require a little common sense,so you don't get burned or shocked. You probably will get shocked a couple of times,it really doesn't hurt. Ignore this suggestion if you have a pace maker or medical condition that getting shocked might hurt you.

Might try disabling spark then cranking over. A cylinder not filling or low compression, starter will increase speed and be uneven on a bad cylinder. I used it many times diagnosing a misfire. Suggested what direction to proceed with diagnosis. If available hook up a vacuum gauge.