Pistons

<font face='Comic Sans MS'>Perhaps age, lots of hard miles, and/or perhaps too aggressive long term timing settings, resulting in a lot of pinging under load.

Years ago I was told pinging was actually the cylinder walls vibrating. Can't speak to the accuracy of that statement, but no question something very violent is going on during each cylinder's power stroke.

Eleven, twelve years ago when I was rebuilding the hipo's engine, I read several articles that supported forged pistons over the hypereutectic alternate for performance engines. So when I did the rebuild, I went the forged piston route. A more expensive choice, but for me it was the correct thing to do. I also went with stainless steel valves because it was the hot rod thing to do. </font id='Comic Sans MS'>

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All of Fords pistons are cast and are really junk and don't last.Any type of hard driving or racing will cause the pistons skirts to crack.Oh I forgot to mention that Ford didn't do a very good job of balancing their motors either.Just upgrade to a set of forged pistons as your motor will be glad you did!

I think a hypereutectic piston can be forged or cast. Compared to cast pistons that would have been used in our cars, even the cast hypereutectic version is way better.

When the original engine in my 66 blew during a SCCA road race in 1973 it was determined the cause was a piston that came apart.

I used Forged pistons in my rebuild several years ago.

They were only about $80 more then hyper-eutectic....

My stock pistons lasted 127k and only had one cracked skirt.

The bores were running 4.006-4.008 so rather than honing to 4.010 and using 4.000 pistons with 4.010 oversize rings, I opted go the minimum bore at 4.020 and std. rings.

Best of luck on your rebuild........

Mark

I take it your block cleaned at .020 ? sometimes 4.020 is not enough to totally " clean " the cylinder walls and make them uniform... When you go to .020, do you hand fit the rings, or can you buy rings that are correct for the bore size....? do the rings come with the pistons or do you buy the rings separately, and what rings do you recommend?<img src=images/icon_smile_big.gif border=0 align=middle><img src=images/icon_smile_big.gif border=0 align=middle>

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.020 oversize rings and pistons are definitely available from aftermarket sources and I have had several Hipo 289 engines with that configuration. ............"

-Fred-

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my Hi-Po engine had the original pistons in it when I bought it in 2000 & was badly needing an overhaul. The cylinders cleaned up well & +0.020 pistons worked/are working great some 43,000 miles later.

I don't understand why folks routinely go to +0.030 pistons without giving +0.020 overbore a chance.

Z.

Edited by - zrayrichter on 11/21/2010 14:26:39

Unfortunately it isn't only a question of the piston being cast or

forged (although forged is inherently much much stronger).

My Boss 302 had the majority of its skirts cracked after less than 10,000 original miles (a very well known/documented problem in that community). And those original Boss 302 piston were forged-relatively heavy TRW slugs as opposed to our strutted castings.

Skirt design, rod ratio and side loading also play into he equation as well as the eternal quest to lighten the reciprocating weight-which if properly done helps everything especially balancing--as long as you don't crack a skirt!!