I have a stock 225 cast crank engine in my 63 dart - Recently 3 pushrods bent - I have been wondering what the "usual" causes of bent pushrods are? I have swapped the head and put used pushrods in from another 225. What should I look at on the old head to determine if it was the culprit in the demise of the pushrods?


stevemattjess@juno.com

Good question below. I'd like to hear more on this one as well, since my stock 225, '66 Valiant engine has the same problem, except only two are bent...


tomglander@netzero.net

Sticking Valve guides are the most common cause of a bent push rod. Overheating, poor oiling or old gas will stick the valve stem (or slow it down) to the point where the rockerarm hits the edge of the pushrod cup and bends the p.rod.

Over reving the engine to the point of valve float is another cause, mechanical damage is a third way it happens. (a past "bonehead" mechanic doing who knows what, like changing spark plugs with Vise-grips and a big screw driver)
DD

Excessive heat, lack of oil, foreign mat'l, tight clearances(or any combination of the above) on the guide/v. stem will cause the guide to seize. A more rare possibility, rocker seizing on the shaft due to the lack of oil, excessive heat, foreign mat'l(or any combination of the above) on the rocker bore/shaft.
Of course, make sure the rocker shaft oil holes are on the bottom of the shaft and the shaft end plugs are in place and secure.

fglmopar@aol.com

Could a weak valve spring (caused by years of storage without turning the engine) let the valves float at 3 or 4000 rpm? Any opinions?


stevemattjess@juno.com

Sure, that's a possible scenario. Stock sl/6 v. springs are not real strong to begin with.
If the engine sat for years, I'd think that there could be rust on the valve stems that could contaminate the stem/guide area and gall the stem, and stick the stem in the guide. The only way to know for sure, I guess, would be to change out the springs for new, or stiffer springs and see what that does. Or, pull the head and carefully inspect the usual suspects. You can learn alot about an engine by close inspection on tear down.

fglmopar@aol.com