I saw that Postons has 10.25 compression forged pistons for the 455.I am wondering if anyone here has used them before?I want to know if they have the right fly cut in them for stage 1 valves.Postons website says they are $389 a set.Who makes them?
Guess you'll have to call Postons and ask. I doubt they are cut at all for the valves. Normally you don't have to worry about valve to piston clearance unless you are 0 decking the block with certain cams. You should always check it with any engine buildup.
Poston's Pistons PSmith I purchased the 10:25 from postons. NO! They are not fly cut. I had to bore the BB over another .010" due to main bearing failure, when I called Postons they told me they were 8.5 to 1. The only reason I got 10:5 to 1 was due to the block and heads being milled a total of .55". If your block is not decked and heads milled they are 8.5 to 1 SPEEDPRO pistons. I purchased the same pistons from TA @ around $500.00 with the valve clearance. Larry70GS is correct, after the engine failure I pulled it down and all 8 exhaust valves had touched ever so slightly. That was with -.005 deck height and .15" off the Stage1 heads. I wish he had told me sooner! But then again, I didn't ask, my fault. In my calculations, my original setup I had a much higher lift camshaft and more duration than the one I damage the valves with. I thought they would clear, I should have ran my dial indicator over the humps before installing. Well its right now. Weeken
Pistons questions PSmith The block was originally decked for a .10" clearance for stock Stage1 factory forged pistons. when I purchased the Speedpros they were manufactured @ .15" higher on the topside. It was a coinsidence that this happened it wasn't planned. However, when you have a felpro gasket it compresses to .41" and I still have .36 clearance in the squish area. If your block is stock you have about .45 of deck height to get near 10:00 to 1 compression you would need a flat top piston. To give you any further help we need to know where you want to be and what you have done as far as block mods. to this point. The speedpro are about the best buy out there at this time. I check J&E Wisco and a few others to get cheap you need to buy off the shelf. Check with TA they can sell them to you cheaper than you can buy direct. However, I did have J&E call me back and offer a better price by about $20 a hole after I bought Speedpros. That surprised me! Don't take the first offer, competition still is king when it comes to pricing in some cases. weekender :3gears:
I asked Poston about those same pistons and what all above said is the answers I got from Tony at Poston. I wound up using the Hypers and with my set up ( clean up mill heads and block, .030 over bore, steel shim gasket ) I end up with 9.8:1 compression. I would suggest Poston's Ultralight piston if you want forged. Talk to Tony over there for all the details.
$373 from summitracing.com http://store.summitracing.com/defau...N=100&Ntk=PartSearch&Ntt=trw-l2353f30&x=9&y=8
Cast piston, $237 from summit: http://store.summitracing.com/defau...p&N=100&Ntk=PartSearch&Ntt=stl-392ap&x=21&y=7
Hypers, $261 from summit: http://store.summitracing.com/defau...N=100&Ntk=PartSearch&Ntt=stl-h392np&x=20&y=11
