diamond piston question

[wrench87]

i have a set of diamond pistons for my 445 fe stroker build part number 42021,i was just informed by my engine builder that the ring land grooves were not cut deep enough? has any one ever heard of this?. i sent an email to diamond i just want to find out to make sure he is not trying to nickle and dime me.
hopefully keith craft or barry r could chime in on this.

[lineslinger]

Have you suggested that your builder speak directly with Diamond?
I installed a set of Diamonds on my FE build...I stayed in the information "loop" but had my machinist and Diamond talk directly about sizing requirements.
When I did final assembly all components been spec'd out and everyone was on the same page...no problems.

[Rick Parker]

Maybe he has the incorrect rings? I would imagine all the pistons are done on CNC lathe and repetative dimensions hard to foul up.(???)

Linesider's suggestion is a good one, get the builder to contact Diamond direct. Or Get the part #'s for the pistons and rings on hand and being used and call them yourself. It's your $$$, dont be timid.

[wrench87]

he said he has been talking to ron at diamond?, i know he did not like the mahle brand rings that were given to me with my rotating assbly from keith craft they were not even file fits. i think he had a set of total seal made for my application?. i just hate buying things twice.

[scottj]

Mahle does a lot of the reduced radial width stuff. If the Total Seals are standard width and the pistons are made for Mahle, the mistake probably occurred when ordering the Total Seals.

[ERA Chas]

My experience with Diamond pistons is that they frequently arrived with land problems such as yours and/or pin hole diameter and pin length errors.

More consistent, correct quality pistons came from Mahle and Manley. Total Seal rings were preferred over Mahle.

Any new parts should be checked for dimension regardless of manufacturer.

[wrench87]

he said he was going to cut the lands deeper for the new rings?, when i bought a balanced rotating assbly i thought it would of been a simple process.

[undy]

Originally Posted by wrench87

he said he was going to cut the lands deeper for the new rings?, when i bought a balanced rotating assbly i thought it would of been a simple process.

I don't know.. I think more research is in order berfore I'd let my brand new pistons go under the knife. I would call Diamond tech myself and ask for the correct ring land depth and compare that to the actual piston's land depth, me taking/witnessing the measurement. That or I'd call Keith, Barry_R, George or one of the other FE engine specialists here. I'd see if they had a set in stock and maybe take a comparative reading for you.

Measure twice, cut once .... applys in carpentry and automotive machine shop work alike.

[wrench87]

i sent a email to diamond yesterday i am waiting on a reply, i guess the good news is he checked it imagine what could of happened if he did not. i wonder if it is possible that these pistons are designed for the mahle rings and he overlooked the measurement when he ordered the total seal rings?. he told me that he called diamond and they agreed the lands were cut wrong but i dont know that to be a fact,hopefully i will hear from diamond today.

[lovehamr]

When I got my rotating assy. from KC I was amazed at how "perfect" everything was right out of the box. But then my machinist just checked all the measurements and machined the block to fit the kit. When I fit the Mahle rings I think I filed 2 and probably didn't really need to on those as all of them fit in the cylinders with end gaps on the small side of perfect. The diamond pistons (actually a BB chebbie part#) were, for lack of a better word, perfect as well. I've forgotten what the size deviation was, but I do remember that I was very surprised at how close they were. After years building Boss 302s and dealing with TRW L2324s and L2325s the diamonds are a giant leap forward. Like Dave said; before I let my new pistons get hacked on by the machinist (just because he didn't like the rings) I'd be on the the horn with Kieth to get the stright scoop. JMHO

Steve

[Barry_R]

Stuff can happen.

But given the number of parts I handle here I have to say that Diamond does not goof up very often. Like pretty close to never - maybe three sets wrong in four years, and hundreds of sets. The radial wall thickness on a ring and could be concievably done wrong if the programming was left in place for a reduced radial ring pack on some custom piston. But your piston is a catalog part and the programming should be locked down pretty well.

If the ring groove was indeed wrong, they should not be lathe cut by somebody. The pistons should be replaced. Ring grooves are more accurate than ANY common machine lathe can duplicate, they are not perpendicular to the centerline - vertical uptilt of +/- one degree is common, and they need to have at least a .010 internal radius to prevent fracture. Unless your machine shop does NHRA Pro Stock or NASCAR stuff he cannot duplicate that even if he tries.

Reduced radial wall rings work very, very well. Most ring manufacturers can suppply them for several bore diameters. Mahle makes an excellent piston ring - manufactured by their Co-Fap division in Brazil. Mahle also owns Perfect Circle, who makes an equally good ring. Federal-Mogul makes an equally good ring. Total Seal PURCHASES their plasma-moly ductile iron based rings from either Perfect Circle, Federal-Mogul, or Co-Fap. Same parts. Different boxes.

[lineslinger]

The Diamonds we installed were spot on, weight and sizing. As mentioned earlier be sure everyone is on the same page before you change/machine any of the specs on your new pistons.
Buying them twice is going to make one person very unhappy.

[undy]

I was going to mention in my other post what Barry hit on, the ability of the machine shop to adequately deepen the cuts for the rings. There's a critcal specified finish that's required on the inner surfaces of ring lands. It, along with other things, allows the rings to load, properly seal, expand and contract to meet a multitude of conditions.

I'm not trying to slam your shop but what they're telling you would give me great pause, to the point of verifying it myself or getting a reliable 2nd opinion.
Asssuming the pistons end up being fine and your shop was wrong, I would also question any other work that they accomplish. That's just me though...

My money's on them having the wrong rings.

Let us know what it ends up being...

Dave

[Mark O'Neal]

A "D" wall ring is bore size/22 - .005.

[Barry_R]

Ya think that he'll know what a "D" wall is?

[Jerry Clayton]

But he only has a,b&c grooves there isn't any fourth groove for an D ring

Only problem I have ever seen with Diamond stuff was there wrist pins which are from a outside supplier

[Barry_R]

Not sure on the outside supplier deal. Most piston companies do outsource pins. Diamond gets a lot of them from Trend products. Trend also makes pushrods. Trend is owned by Bob Fox. Bob also owns - Diamond. And Spintron. So he outsources from himself....

[Mark O'Neal]

Originally Posted by Barry_R

Ya think that he'll know what a "D" wall is?

I was hoping......

[wrench87]

i spoke to the engine guy he said he uses a 5 axis cnc machine to cut the lands, he said he does this quite frequently on some of his high dollar off shore boat engines. he said he just goes in and does waht he has to he doesnt redesign the factory land. he feels when he sends them back to the manafacturer they dont take the time he does to make it right and more then one occasion they come back and the rings have to much play?. i was wrong i thought he said he was using total seal but he is using a custom ring from cna i have never heard of them.

[lovehamr]

Wrench, have you talked to Keith? If not, why not? You bought the assy form KC right? If something is wrong with it then why, in the name of The Great Pumpkin, are you willing to throw good money after bad without getting the straight scoop from the guy who you bought the kit from? Based on the boat guys word? I've gotta say (even if you don't like me afterword) that after years of dealing with "witnesses," your off shore boat guy's words have a certain "stinkiosity." JMHO of course and everybody has one or twelve of those.