I had two 351 engines and both had piston slap and both got quiet when they got warmed up as the aluminum piston will expand faster than the cast iron cylinder.

 

Only in OD. I can run it with OD and above 60. I can run it with the OD switch turned off and no vibration.

 

Insure the transmission is filled with MerconV and add a tube of dr tranny shudder fixer to the transmission. It has fixed torque converter shudder for me on more then one Ford. Not impossible to have piston slap. But usually exhaust leak look at the egr tube. Seen that more then once on a 351. They crack where the expansion wrinkles are made in the tube, under the insulation sleeve.

 

Never heard of that product but at $500 to get the converter replaced I am willling to give it a try. Thanks. Guys, if it is a piston slap will it last doing that or is that an implosion waiting to happen?

 

On my 5.8L the piston slap broke the skirt off the bottom of the piston and I had to replace the piston.

 

I started pulling of plug wires one cylinder at a time and cranking up the engine. The ticking sound never went away. I used a long extension that I could listen through and the sound is on the drivers side rear cylinder. Cant be heard at all from the pass cylinder bank when using the extension and on the drivers side it gets louder through the extension as you move to the rear piston. the sound is metallic like a lifter instead of an exhaust leak but I could be wrong.