Possible bad flywheel Help Please!!

[rdlyn13000]

So I have this truck for sale on craigslist right now and had a guy come take a look at it the other day. He seemed to know chevy trucks pretty good and said he worked on heavy equipment for a living. He said these 305's are known for the cams going bad, getting a flat spot on one of the lobes. This did make since when he was explaining it to me how either the exhaust valve or intake valve wouldnt open all the way causing an imbalance creating the vibration. Any thoughts on this? Would doing the compression test tell me if I have a bad cam or not? I would really like to get this vibration taken care of. Thanks

 

[Tempted]

This is why I told you to start looking for a miss in the beginning. Yes, a flat lobe is a possibility. It will cause a miss, which will cause a vibration at different speeds. Even if the cam isn't the issue, I'm still betting the vibration is being caused by a miss.

 

[rdlyn13000]

This is why I told you to start looking for a miss in the beginning. Yes, a flat lobe is a possibility. It will cause a miss, which will cause a vibration at different speeds. Even if the cam isn't the issue, I'm still betting the vibration is being caused by a miss.

Yeah I remember you saying that I just havent dug into it. Its not my daily driver so its been sitting. If it is a mis but its not the cam what else could it be? I am going to have someone to a compression test on it soon.

 

[Tempted]

Rings, valves, springs, intake blockage, etc. First thing to do is find which cylinder it is. A compression test won't tell you if the cam is flat. You'll need to pull the valve covers and use a dial indicator on the valve stem to measure the distance the valve moves.

 

[rdlyn13000]

Rings, valves, springs, intake blockage, etc. First thing to do is find which cylinder it is. A compression test won't tell you if the cam is flat. You'll need to pull the valve covers and use a dial indicator on the valve stem to measure the distance the valve moves.

Man this just sounds like a big headache! Ive never dug into motors and really dont plan to, hopefully someone will just pick this truck up as project or something?

 

[Tempted]

It isn't hard at all. 4 valve cover bolts is all the wrenching you have to do. The rest is just rotating the engine and recording the distance the valve travels. You will want to pull the plugs out, makes rotating the engine much easier. And remember to put it in neutral.

 

[rdlyn13000]

How do you rotate the engine? By hand or turn the starter?

 

[Tempted]

Hand.

 

[rdlyn13000]

Well she's gone, I ended up selling her tonight!