Pistons
 

Hi, I have a gen 6 502 that was taken out to 4.530 using wiseco pro tru pistons. Turns out one is junk and they stopped making them. I have been offered a set of je pistons in 4.525, will that be ok to use them or will I end up too much clearance?
cheers

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I always thought forged pistons NEEDED a .005 clearance?

That will be very loose.

Send the pistons out to line2line to get their ablative skirt coating done. It will tighten the clearance up. Be reasonably priced.

Piston to all clearance will depend on bore size and piston material.
https://cimg7.ibsrv.net/gimg/www.off...c90cd446ad.jpg

Piston to wall clearance has many factors
piston material
intended use (n/a vs blower vs n2o)
endurance or drag race etc.
.005 is pretty common on a marine bbc. I’ve gone as high as .008 in some applications

.0075 is my current build with blower use.

It all depends on what you actual bore size is. The ProTru piston usually had .004-.005 piston to wall. That'll probably put your undersized piston at .010. if it's a 2618 piston you'd probably be ok. If it's a 41xx material it's wayyyyy to much.
Wiseco will make that piston for you. You can buy just one. And there's odds they'll have some stashed away somewhere. Call them direct. Don't rely on someone in the middle that makes money off the sale.

thanks, I did speak to them but he said they stopped production around 7 years ago, they asked the weight of my piston to see if they have anything to match. So hopefully they do

1. The J/E piston is for a 4.525 bore OR is it for a 4.530 bore and measures 4.525?
2. are either set of pistons 2618 or are they 4032?
3. when you buy say a set of J/E "4.530 pistons", unless you call JE up and custom order a set of ACTUAL 4.530 OD pistons (which would require a 4.535 bore =/_), you are actually getting a piston that fits that 4.530 bore size once accounting for "normal" clearance. Now, lets say the piston is a SRP 4032, it would measure about 4.526, a 4.530 bore would give you .004 piston too wall. Lets say it was a 2618, it would be more like 4.525 OD and give you .005 piston to wall in a actual 4.530 bore. Now, lets say you wanted a target clearance of .007 for some reason, you might hone block to 4.532 , or if piston started life a 4.525 and is worn to 4.524 youll end up at .006 or higher. You may very well NOT have a problem, Smitty

Picture of the junk piston?