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

..

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?

the JE pistons that I was offered measure at 4.524 and are 2618 material.

https://cimg8.ibsrv.net/gimg/www.off...cd9fa7898.jpeg

I was running a 427 in a drag car years ago and I think it was somewhere around .013" skirt to wall clearance... not because that was ideal, but because I didn't want to put new slugs in a worn-out block.
It was a little noisy on cold startup but ran like a scalded cat with a 325hp shot of nitrous.
Of course a short stroke with long skirts is alot different than a longer stroke with short skirts...

If it were me I would order a fresh set of custom pistons to match the existing bore. JE will make them however you want. I ran a 513 one time that was a .137" over GM block and a 4.250 crank. JE made me 10 pistons for it.

looks nasty but might work with new rings. Without knowing how it looks, you could be happy boater with that piston in your engine.

I’m sure that pitting would gunk up again sticking the rings like it did

https://cimg4.ibsrv.net/gimg/www.off...16b5dc3ce.jpeg
https://cimg8.ibsrv.net/gimg/www.off...94c9b2229.jpeg
https://cimg0.ibsrv.net/gimg/www.off...cbd7c0b4e.jpeg

What’s the history on that engine? Was it lugged?how many affected, just the one? Carb or injected?

I wouldn’t run those.

motor stuck a valve on cylinder 4 and injested water in cylinder 4, it says and must have pitted but didn’t affect the bore, just needs a hone. Rest of the motors is fine, heads have been rebuilt since.

this is one of the JE pistons

https://cimg2.ibsrv.net/gimg/www.off...c515177d5.jpeg
https://cimg4.ibsrv.net/gimg/www.off...6931f1bd2.jpeg

Ring lands don't look good.

Throw it in the garbage.

do you know what the correct rings are for the 4.530? Is it the total
seal
CR9190?

so,we see what the j/e measures, what does your damaged piston actually measure then, 4.530?

damaged piston measures right around 4.525

It sounds to me like the JE piston is made for a 4.530 bore so it should work fine. What is the part number ??

So, got hold of wiseco and they sorted me out with a piston and pin combo that weighs 4 grams more than my original set, will this matter or should I get the 4 grams removed from the piston?

If your removing 4 grams from pistons, take it out of the wrist pins. 4 grams is a alot of aluminum !

very true - for a direct comparison to the amount that would have to be milled off, a 5 cent nickel is 4-5gr actual weight.

ok, not easy to get milling work done like that where I am. Would 4 gram heavier piston make a whole lot of difference? Wiseco said it would be fine but not sure

SeanyB82

Yup. Just make the chamfer on the ends of the wrist pin IDs a little bigger, You'd be surprised how little it takes.

Thanks. Brad.
(937)545-8991

There are alot of forums where Wiseco said 5 grams was acceptable....that said, if you bought a set from Summit, they would take a set back where there was that much spread and replace them with another set drop shipped from Wiseco... that is Summit racing customer service ideology vs Wiseco.

That said, There can be 5 grams of carbon on a bad engine and they still live

Most every shop out there over balances the crank. Adding 5g to the piston rod assembly will never be noticed.

You could easily touch inside of wrist pin end with a die grinder with carbide burr and keep checking it on a scale until you hit your goal weight, prob take a couple minutes so you don't agonize over it, Smitty

Pistion
 

I weighed a dollar bill it weighs 1 gram,u would not even notice it,5 gram difference,find another pistion I have a few sets what do u exactly need

got the new piston with a heavier pin, only one close to match the weight but came in at 3 grams lighter than the original piston and pin, is this an acceptable weight difference?

That wont hurt a thing. Stop worrying and tun it.