Join Date: Sep 2014
Location: Fernley, Nevada
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460 Autotec forged piston slap and how I reduced it
I have Autotec forged pistons and my builder told me that for the first minute or so I would have to endure piston slap due to tolerances and piston design. I removed all the smog before the engine build. I did everything I could think of to reduce internal friction losses including full-floating pistons.
My builder was correct and there was piston slap. One smog device I believe to actually benefit an engine and that is the ported vacuum switch which is downstream of the thermostat and sits on top (of mine) of the t'stat housing. One set of ports will block the vacuum advance until coolant temperature opens the thermostat; I have the smog port blocked off. This facilitates a faster warm up of the engine. So I decided to reconnect it and found that the retarded timing helps to reduce and eliminate piston slap on my 466 on a cold start. It's a cheap fix and worth a try.
BTW, I just got 14.88 mpg but my thread on how I did it got a 'Closed Thread' for some reason. I will try to avoid it in the future. Pretty good for 6,000#+ F-250 High Boy 4x4 at 4,000' elevation. Stock T-19, 3.54 gears and Dana 70 rear end.
When I can buy a better piece of hardware than what I have and it is approximately the same cost as reworking my old, tired and stressed part then I feel I am ahead of the game.