Piston pin coatings

[Matt80]

Hi, last week a customer told me a piston kit I sold him had the pin clearance completely off.
The kit is from a big and reputable Company, so I wanted to have a look myself as it would have been a little unusual such a big issue.
But customer was right, and while the pin are perfectly in spec and as per Company paper, the piston pin housings have an oil clearance the double the value it should be!
That is to say the housings are 0.0008" more than their specs.
Now, I already sent them an email but didn't had any reply for the holidays, and moreover I don't know how and if we will resolve this issue as I bought this kit one year ago.
Anyway here is the question: are there coatings or treatments, like DLC or so, that could increase the pin diameter of 0.0008"?
Pins are standard steel.
Thanks

[mag2555]

You would not want to rely on a coating to take up extra clearance!
Have the piston manufacture start over,

[Dave Koehler]

Just wondering what is the intended engine use and what was the actual clearance?

[BlitzA64]

I had that issue once on a SBC, went from .927 to .928 pins and fit them to the rods and pistons

[ProPower engines]

as mentioned I would use an over size pin to correct the issue. I had had the same thing before as well not a complete set with larger pin bores but a few in a set of 8.
The range of over size is very common and it should not be an issue. I would remind the customer since you did not open and check every part he must bare some responsibility for not bringing it to your attention for such a long time.
While it may not be an issue with your supplier to supply a larger OD pin set some one has to bare the cost of the resizing of the pistons after such a long time

[MadBill]

Just wondering what is the intended engine use and what was the actual clearance?

Yes, under extreme usage that extra eight tenths might be a plus.

[blwilliams]

Wondering what this build is for.
If high vacuum is going to be present in the crankcase the extra clearance will be a plus.

[Matt80]

Just wondering what is the intended engine use and what was the actual clearance?

Turbo engine, Street abuse and track days. Wet sump and vented to atmo.
The Pins are .86601 and housings should have been .86686, but they are .86775.
I already installed in the past high clearance pins, but ended being very noisy.

[Charliesauto]

Just wondering what is the intended engine use and what was the actual clearance?

Turbo engine, Street abuse and track days. Wet sump and vented to atmo.
The Pins are .86601 and housings should have been .86686, but they are .86775.
I already installed in the past high clearance pins, but ended being very noisy.

Trend or Precision Products can supply you a .867" pin for less than the coating will cost.

[Roundybout]

DLC coatings are only microns thick and used for their anti-friction/wear properties so they wouldn’t be much use in this clearance issue. The only things I’m comfortable with coating to make up clearance issues are pistons and possibly bearings.

[Matt80]

Happy end, the Piston Company saw the issue and sent bigger pins for free