bending pushrods?

[stuart olson]

Hi all. Ive got a 360 in a 75 that started bending intake pushrods back in May. Always did it immediately upon cranking. I assumed something had gone terribly wrong, and seeing as it always trailed a cloud of blue smoke upon start-up. I figured it was time for a rebuild. Which led me down the path of doing a 445 and all this fun sort of thing. But seeing as that is going to be a spring thing I figured I would take another look at my toast engine to see if I can get a few more miles out of it and keep working out other bugs and other improvements this fall. I pried it open today and found no evidence of foul play. The bores still look decent and there is nothing obviously wrong with the heads. Any ideas?

[stuart olson]

View of valves.

[WConley]

I wonder if you have one or more lifters bleeding down and collapsing.  Starting up with the resulting big lash can kick a pushrod out of position, creating bad ju-ju.

Running thin oil?  Change anything on the engine in May or just before?  It would seem odd that you have sticking valves on the old beast.

[stuart olson]

Put a Holley 500CFM 2V on about 3 weeks before it went to crap. Only other thing was I got the front tank working again about a week before.

[Bolted to Floor]

I bought Pops old F250 years ago with a 360. It had been sitting for years with gas in the saddle tanks. I drove it a few weeks then switched over to a saddle tank on my way to work one morning. That afternoon, it didn't want to start, was smoking when it did. Ran like crap too.

Pulled the valve covers in the driveway and found a bunch of bent pushrods. Pulled the heads and took to the machine shop. The old gas had caused multiple valves to stick. They had to drive the valves out with a hammer. They had to open the doors to air out the shop from the smell of old stale gas coming from the heads.

May want to have your heads looked at.

[scott foxwell]

Last time I started an FE that bent a bunch of pushrods, the nylon timing gear had finally slipped and jumped time.

[chris401]

Put a Holley 500CFM 2V on about 3 weeks before it went to crap. Only other thing was I got the front tank working again about a week before.

The two below post are the most common problem. Your intake valves will build up a varnish on the stems with old gas. The varnish has epoxy like qualities when the engine cools.


The jumped timing chain will usually bend exhaust valves before it bends intake valves.

[fryedaddy]

i bent a few a while back,i thought a backfire at startup maybe caused it.

[stuart olson]

I hate to admit it but I think the stupid explanation is the correct one. Bad gas. The intake runners have this sticky tar like stuff all over them. Hands are still stained a day later. . Thanks for the help fellas.

[fryedaddy]

i had some gas dry plum out in my tank after letting it sit a few years with a blown motor.i put a new engine in and the dried gas had left a real fine sand in the tank and when i added new gas to start it up it ran fine for a day or two then the fine sand clogged up some passage ways and messed up my carb