Thread: top end engine teardown

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We'll I finally got around to the teardown of the engine to determine the valve tapping and smoking. First I did a compression check. All cylinders were just around 170. All the plugs , when removed had black carbon. Carb probably adjusted too rich. Number 8 cyl. plug looked a little oil fowled. Possible smoke origin. Number 7 intake pushrod was demolished where it fit into the rocker. Pushrod had crumbled into pieces and has shortened the pushrod by 1/4". There a good reason for a valve tap. I've never seen a pushrod crumble. The rocker arm socket still looks like there is no damage. I guess I'll drop off the heads at the machine shop and have them go over them. Pistons and valves are coated with carbon.

I'd sure verify adequate valve spring retainer to seal clearance for the lift of cam you are running.

On a Corvair I had once, the same thing happened. The ends of the pushrods crystallized because of getting hot, probably from lack of lube. They broke off in chunks a little at a time. I was on a 500 mile trip and managed to pull off a couple of times to adjust the rockers, then when I got to my buddies house, I replaced all the pushrods.

Originally posted by Deluga
We'll I finally got around to the teardown of the engine to determine the valve tapping and smoking. First I did a compression check. All cylinders were just around 170. All the plugs , when removed had black carbon. Carb probably adjusted too rich. Number 8 cyl. plug looked a little oil fowled. Possible smoke origin. Number 7 intake pushrod was demolished where it fit into the rocker. Pushrod had crumbled into pieces and has shortened the pushrod by 1/4". There a good reason for a valve tap. I've never seen a pushrod crumble. The rocker arm socket still looks like there is no damage. I guess I'll drop off the heads at the machine shop and have them go over them. Pistons and valves are coated with carbon.

I saw you where you running a 292 Comp. cam.With spring pressure needed to open and close a valve that has over.500 lift you would need a better push-rod than stock.If you are running guide plates than you would need hardend push -rods.I would also look at your valve train geometry.

I dropped the heads off at the machine shop and was told the following: The valves that were to have been new, probably weren't. They were stock valves. The 3 angle valve job was done by hand. The retainers were mix matched, probably whatever was laying around. The studs being pinned, really isn't done much anymore. So that blows the idea that the engine was built by a true chevy pro. I am considering pulling the bottom end out and taking it to the machine shop. Who knows whatelse they'll find. I was told that they have seen alot of crap being bought from E Bay. Buyer Beware!!!!