Mark IV 7.4L engine 1989 K3500

[Schurkey]

You bought the engine, or you bought the truck?

What diameter are the pushrods?

BBC are bad for bending pushrods, or having the rockers jump off the end of the pushrod. It happens, generally at higher RPM, and generally (but not always) on the intake side rather than exhaust, just like your engine. The intake side has bigger, heavier valves. There's a reason the higher-performance engines got 7/16 pushrods.

MAYBE all you need are new pushrods (of 3/8 or larger diameter--for Foo_k's sake do not spend money on replacement 5/16 pushrods) and valve springs, and perhaps fresh guideplates to match the (larger?) pushrods. Heavier-wall pushrods than plain ol' stock replacement 3/8 are advised.

If this were me, I'd pull the pushrods off the engine, and perform a cylinder leakdown test on all eight, to see if the valves are bent.

The bonus here is that with each cylinder at TDC, and the cylinder filled with compressed air from the leakdown tester...you could easily change valve springs on that cylinder at the same time.

 

[454cid]

How did this engine get a shovel full of dirt and grass clippings in it?

Last year there was a early truck at the auction house I go to.... MK4 454, but partially stuck, from down south or out west. I would have loved to have had it, as you usually don't find them in MI anymore, in good shape. I was looking for a winter daily at the time, so a project was out of the question.