Got a call from the machine shop yesterday and they said the block had "fire rings" in it and needed to be milled. I said "whoa...".

I have never heard of this before. I know what is most commonly known as "fire rings" are a stainless ring installed to help seal off the combustion chamber. But the Customer Service guy (not machinist) said the block had "fire rings" as a defect. I am tried to get clarification and he just repeated the term. I am thinking the block has some kind of pitting/corrosion around the top edges of the cylinders, even after boring. He also did not say how much they wanted to mill the block.

Is this a "thing" and how would you all recommend I proceed? This is a 1994 7.5 that I may doing a stock rebuild on (save for a Comp Cam EFI cam) for my 1967 F-250 4x4.

Thanks!
Chris

 

Went to see the block, still had it in the boring machine.

What it was is the head gasket fire ring left a mark on the block. Could not feel it, but it was evident. Decided to mill the deck just to be safe, as we are in to it this far...

 

The "fire ring" is not a problem unless the head gasket was leaking and eroded the edge of the bore. How much did they take off?

 

If your going to mill the block anyways then I would find deck height and see how much needs to be milled to get to zero deck.

 

They will just clean it up, minimal milling.

Yes, I could zero deck it, but this is basically at stock rebuild. Going to stay EEC-IV in my 1967 F-250 4wheel...

 

Got block back, the took 0.008" off the deck. Needed it, but minimal! .030 over on the bore.

Time to start assembling!