motor mounts

[82eLCo77C10]

Alright. I'm still new to the 350 SBC scene.
I have a 77C10 350 SB. My question on the motor mounts is, one, will it cause a loss in power. And two, will the vehicle feel like it has more vibration to it?

 

[Sachmo]

Motor mounts won't affect power. mainly just notice the engine rock more when given throttle. A loss of power and vibration sounds like a dead cylinder

 

[82eLCo77C10]

Thank you. Any ideas of where and what to start looking at? It started two days ago. The truck was warmed up to normal temp. I left my work and when I went to throttle into it, it shuttered and ever since its had a lower vibration. You can notice it more when its in gear. I changed the plugs out last night. And that didn't seem to help. It does how look like there is an oil leak on the lower side of the heads on both sides of the block... I cleaned it up last night when o changed the plugs and the oil hasn't shown back up.
Not sure what's up. Any info would help.

 

[87sierra]

if it is a dead cylinder the easiest way to check is by pulling spark plug boots one by one while engine is running if it gets worse put plug back on and go to the next cylinder until you find the dead cylinder which will cause no change in the idle also look at the spark plug wires for any cracks or melting and burns and check the cap and rotor for corrosion

 

[82eLCo77C10]

Ok thank you. I will do so tomorrow. Oh, also the plug wires were put on 12-07-12 (Bosch 8mm) also changed cap and rotor (msd). When I changed the plugs out last night, the plug wires seemed solid (good connection). But like I said in previous post, changing plugs didn't seem to help. Didn't get worse or anything. But didn't change anything. The vibration didn't start until I put new valve covers on. (chrome with Chevy emblem.) they were off my dads elco. I did notice on the covers, where the oil breather and pcv valve seat in, there were spots where the rocker arms had rubbed a hole in them (from the elco). Could it be at all possible that that is causing the problem on my motor?