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5.7 piston to valve clearance.... #2329104
06/30/17 12:25 PM
06/30/17 12:25 PM
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Medlock51 Offline OP
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Any known reason why the stock pistons can't be cut for additional p2v clearance when using stock pistons?

Nothing new about this as it was being done 60 years ago..

My 5.7 will need new slug to get my needed compression but a guy on a budget using stock pistons could save some cash doing this.

Last edited by Medlock51; 06/30/17 12:26 PM.
Re: 5.7 piston to valve clearance.... [Re: Medlock51] #2330085
07/02/17 08:47 AM
07/02/17 08:47 AM
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gregsdart Offline
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Check the thickness where you want to cut reliefs. I am not sure what is the minimum you need after cutting, but I bet the factory didn't put any extra metal in those stock pistons.

Last edited by gregsdart; 07/02/17 08:48 AM.

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Re: 5.7 piston to valve clearance.... [Re: Medlock51] #2330434
07/02/17 11:23 PM
07/02/17 11:23 PM
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Medlock51 Offline OP
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We made our own cutters out of used valves... just cut a notch for a cutting edge and ground to suit.. Did this in the 60's until we heard about fancy pistons years later...

Re: 5.7 piston to valve clearance.... [Re: Medlock51] #2330742
07/03/17 04:13 PM
07/03/17 04:13 PM
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HotRodDave Offline
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They have extremly thin pistons and the new material is very brittle I would not dare try to run one that way. Seems about .100 thick pistons (hard to get my caliper down there), if you cut even .050 you only have .050 left and now it has a stressriser in a very weak piston that you are bumping up the power on, very bad idea.


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Re: 5.7 piston to valve clearance.... [Re: Medlock51] #2331216
07/04/17 10:22 AM
07/04/17 10:22 AM
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ric3xrt Offline
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Don't do it, like Dave said the top on these stockers is very thin


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Re: 5.7 piston to valve clearance.... [Re: Medlock51] #2331603
07/04/17 10:14 PM
07/04/17 10:14 PM
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Medlock51 Offline OP
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I would believe the hyper pistons are thin... but maybe a .010 cut would work if needed. Just spit ballin' here guys... lots of stuff won't work on paper but on a poverty build it will.

Re: 5.7 piston to valve clearance.... [Re: Medlock51] #2331931
07/05/17 02:42 PM
07/05/17 02:42 PM
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HotRodDave Offline
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still going to make a stress riser on a very thin brittle piston. .010 less valve lift is not gonna hurt as much as a busted piston.


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Re: 5.7 piston to valve clearance.... [Re: Medlock51] #2332429
07/06/17 12:12 PM
07/06/17 12:12 PM
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ric3xrt Offline
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Here's a stock 05 piston cut
Use your best judgement, it's as thick as some of the later BB's but these 5.7 are notorious for being fragile

0706171000a.jpg0706171000.jpg

Truth has no agenda, but those with an agenda make their own truth.
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Re: 5.7 piston to valve clearance.... [Re: Medlock51] #2332698
07/06/17 07:15 PM
07/06/17 07:15 PM
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Medlock51 Offline OP
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A 4032 hyper will always be a little more fragile by the nature of the alloy.

Sometimes a little extra p2v clearance is needed....looks like there's enough meat where it counts to be able to notch them.

Again...I'm just tossing this out there in case a guy needs a bit more clearance. I'm going to guess I'll keep my 5.7 under .600 lift depending on the pistons I choose...lots more to do until then.

Thanks for that photo....

Re: 5.7 piston to valve clearance.... [Re: Medlock51] #2337051
07/14/17 08:20 PM
07/14/17 08:20 PM
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dogdays Offline
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4032 is not normally classified as hypereutectic. It has 12.2% silicon which places it right at the eutectic point.

Alcoa 390 is 16 - 18% silicon and is what I believe most hypereutectic pistons are made from.

390 alloy first came to the high performandce automotive world in Can Am racers where Chevrolet pioneered the use of Reynolds 390 blocks which allowed larger bores because they had no sleeves. These engines were very successful. Imagine their distress when the exact same principle bombed in the Vega. But now most high dollar Euro engines are using the same alloy or close, and using different lining methods for the cylinder wear surfaces.

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