re-use diamond pistons or go to something different?

[kidglok]

due to various issues ive decided to pull the motor and rebuild. build was as follows:
Diamond Pistons, 212/212 roller cam, stock rods, stock crank .10 under, aftermarket timing cover (?), steel center caps, champion heads

question is, if the pistons and bore are g2g is there any advantage to going with a different piston? (je, cp, wiseco) i know some people arent fans of the design of diamonds. Im building to gradually creep into low 10's once my confidence in tuning ability exceeds my conscience.

so far i have s/s scat rods (ebay), s/s forged crank/bhj balancer, sfi flexplate (thanks to Mike @ fullthrottle).

 

[Chuck Leeper]

A couple things to check on the pistons:
1. Check ring groove clearance. Looking for collapsed lands, etc.
2. Check the skirt dimensions to see if they are collapsed.
3. Wrist pin bores OK?

 

[KL Mallender]

If following Chucks inspection(which I agree with) and nothing abnormal rears it's head, I would deck the block to achive a 0.030 piston to head clearence including head gasket thickness(assuming that you don't run more than 0.005 piston to wall clearence).
If milling the deck would require more than a 0.030 cut to achieve this, then it's best to leave well enough alone and button her back up.
Might want to look at your oil return ring(scraper) for adaquate return area(holes/slots), you have enough carbon build-up and a "washing" by oil on your piston crowns to indicate oil making it's way past the rings.
Good luck,

Kevin.

 

[Grumpy]

ya... if they are ok I'd use them.. You have the same motor as me except we have a girdle instead of caps. We ran 9.92 @ 138 with your motor. 10s would be a walk in the park.

 

[kidglok]

thanks guys, mind if i print the posts and hand them to the machine shop? lol
im still learning all this stuff so i have to research the lingo a lil bit to understand lol
does it matter if the scat rods are set up for floaters and the pistons i have are not?

 

[quickt]

due to various issues ive decided to pull the motor and rebuild. build was as follows:
Diamond Pistons, 212/212 roller cam, stock rods, stock crank .10 under, aftermarket timing cover (?), steel center caps, champion heads

question is, if the pistons and bore are g2g is there any advantage to going with a different piston? (je, cp, wiseco) i know some people arent fans of the design of diamonds. Im building to gradually creep into low 10's once my confidence in tuning ability exceeds my conscience.

so far i have s/s scat rods (ebay), s/s forged crank/bhj balancer, sfi flexplate (thanks to Mike @ fullthrottle).

Low 10s get another set if pistons.

 

[kidglok]

 

[kidglok]

Low 10s get another set if pistons.

how do they tend to fail?

 

[quickt]

how do they tend to fail?

You can do a search there's plenty of info. Cracking in the thin spot to first ring land. Just one there are many.

http://www.turbobuick.com/forums/engine-tech/308688-broken-diamond-piston-pics-why.html

 

[cruzn57]

in the pic of the bottom of the block,
is that a crack from the cam bearing towards the main?

 

[pacecarta]

i just inspected it , its a casting flash line

 

[Phoneguy]

Low 10s get another set if pistons.

I hate you !!!!! :biggrin:

Bryan

 

[kidglok]

I hate you !!!!! :biggrin:

Bryan

lol what pistons you running phoneguy?

pacecarta and i just tok a look at the pistons/rods/mains/bearings...all look decent enough. I suppose if im going with new pistons i can sell off the whole rotating assembly? or i could get another block and caps and keep this one as a spare

 

[KL Mallender]

I hate you !!!!! :biggrin:

Bryan

Thankfully we don't shoot messengers bringing home the truth anymore, pretty sure we gave that up after the witch hunts in Boston went goofy, that was a few hundred years ago, can you just imagine how stupid things were then? Everybody here would be considered a "Heretic" back then.
Religious beliefs can get in the way of progress at times, we humans have proven that several times over the years.

Kevin.

 

[Phoneguy]

lol what pistons you running phoneguy?

pacecarta and i just tok a look at the pistons/rods/mains/bearings...all look decent enough. I suppose if im going with new pistons i can sell off the whole rotating assembly? or i could get another block and caps and keep this one as a spare

Obviously I am running Diamond pistons...i had a meltdown in May after returning from NC. Melted a head,block,1 piston,couple push rods. I am now looking at doing the rebuild over the winter.
Bryan

 

[Phoneguy]

Thankfully we don't shoot messengers bringing home the truth anymore, pretty sure we gave that up after the witch hunts in Boston went goofy, that was a few hundred years ago, can you just imagine how stupid things were then? Everybody here would be considered a "Heretic" back then.
Religious beliefs can get in the way of progress at times, we humans have proven that several times over the years.

Kevin.

LOL.
Just busting his chops...he is doing the rebuild !!!

Bryan

 

[kidglok]

update from machine shop

machine shop checked the bore and its .020 over (as expected) but the piston to wall clearance is 6 thou (5 from piston 1 from bore i think?), do we rather run 5? if i keep the same bore he said it will be a little lose. Would you recommend going .030 over and 5 thou clearance or keep it at .020?

Thanks for the help!- james

 

[SloGN]

Diamond Pistons

Lonnie and others


Is there really a problem with the diamond pistons. I have them in my stroker motor. so far i have been 10.50 @ 128 in BG @ low boost.

I really hope not

 

[kidglok]

from what ive heard, there not as big of a problem on race gas...

anywho, im not gonna take the chace so i ordered up some JE's. I mean lets be realistic, if you detonate anything hard enough no piston in the world is gonna survive. From what i understand is the design of the outside ring by the valve reliefs is thin enough to cause hotspots and weak points in the integrity of the aluminum.

 

[quickt]

Lonnie and others


Is there really a problem with the diamond pistons. I have them in my stroker motor. so far i have been 10.50 @ 128 in BG @ low boost.

I really hope not

IMO they are a poor design. If they fail they all seem to fail in the thin spot of the inverted dish. If it not broke I wouldnt fix it. But if I had the engine apart like this fella I certainly wouldn't reuse them. I built 4 TSM engines about 5 Years ago using those pistons. Every engine had piston failures exactly the same. All 4 were TSM power plants and all 4 were 9 second rides.