The Stovebolt Site Forums The Shop Area Engine Shop Clatter, clatter, boom??

Was sitting with my 261 idling at a light yesterday when suddenly there was a ticking followed by engine backfire--clatter, clatter, boom, clatter, boom, clatter, boom. I immediately pulled into a nearby parking lot and summoned my son with a car trailer. This morning I removed the valve cover to look for broken springs, lifters, etc.

The top of a push rod had broken and the piece was lying in the oil on top of the head.

Cause? Effect?

rocker too tight?
oil passage clogged in pushrod?

Cause????? Effect$$$$$$

Try a compressino test before you just fix what you can see

New set of push rods coming from Patrick's--didn't replace with new when engine was rebuilt. Dumb move. Will do compression test, etc. prior to saying all is well. Thanks for the response, guys.

Any chance they were too long putting too much strain on things?

Nope. Were 11 1/4" long. Original to the 261 taken out of a running '59 Chevy grain truck prior to rebuild.

Did you put in a higher lift cam without replacing the valves/guides? Did you check the rocker arms for wear? New valve springs? It sounds like something hung up and broke the pushrod.

You can run the compression check before the pushrods arrive and get a headstart on the other parts you'll need.

Be sure to open the throttle all the way while doing the test

How many miles on engine? Recent rebuild? Have seen valve guides installed and not have proper clearance.

Jim, what good is a compression test if you can't open the valves?

Sorry JB

Your right I been sick

I tend to interchange compression and leakdown test.....since I almost never use a compression tester

Your probably right 4onthefloor, I went with a Howards cam and new guides but old intake valves you can see the results here in V8 Reason
http://community.webshots.com/user/zeker6
what a sorry day that was. I think the unworn portion of the valves tightened in the new guides (Head done by a machine shop) because of the higher lift got a tap from the piston the rest is history, The darn intakes were the only thing not new in the valve train . Zeke

New stock 261 cam, rockers, valves, guides, springs, hardened seats, bored .60, head shaved .20, ported and polished. 8K miles on engine. See picture link on my post.

No problems since original set-up until now. Push rod appears to have suffered from metal fatigue prior to this problem.

Yes, definately do a leakdown test, then you will know if you bent a valve when the pushrod broke.

Soooooooooo What did you findout?????