VIDEO... Piston rings

(Jim XK140 FHC) #1
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(Robin O'Connor) #2

I’m not sure about using the chromed top rings, never quite happy if they ‘bed in’ properly.
You questioned if the second ring was iron, yes they are cast iron as are the top rings I think you will find.
The rings in bag 4 are old style oil control rings/scrapers, the spreader and two thin rings are the later type.
Correct regarding the colours needing to be visible, if they ain’t you’re not getting that piston in the bore :slight_smile:

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(Paul Wigton) #3

Unless in a brand new bore, I would never use chrome rings.

Had to eat a few overhauls… and engine aint tasty.

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(Jim XK140 FHC) #4

Thanks for the advice .
I have emailed Grant to see what they suggest .
Looking at their web site they offer 2 versions of chrome plated , steel or cast iron . The ones I have are cast iron .

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(Paul Wigton) #5

Again, unless they are going in pristine, new bores… I’d go with cast iron.

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(Jim XK140 FHC) #6

I have now bought a new iron “Hastings” ring set . Thanks for the tips.
This is the message from “Grant” , from the vice president no-less…

Chrome Set is for premium and required good honing finished in order to use Chrome rings of the set.
Please see attached recommendation for honing.
If you are not capable then use Plain top ring which is under part P1145 instead of C1145

The following is general information only. For more specific information please refer to OEM specifications and or your rebuilder specification guide.

Cast Iron Rings:

Leave at least .003” stock to be removed before final bore size. Boring can sometimes leave roughness as deep as .003”. In order to end up with a proper finish, enough material should be honed to remove all torn and folded material.

Use a 220 grit stone and remove .002” to .0025” of stock.

Remove the final .0005” with a 280 grit stone. If necessary polish briefly with a 320 grit stone being careful not to burnish the surface.

Chrome, Steel and Moly Rings:

Leave at least .003” stock to be removed before final bore size. Boring can sometimes leave roughness as deep as .003”. In order to end up with a proper finish, enough material should be honed to remove all torn and folded material.

Use a 220 grit stone and remove .002” to .0025” of stock.

Remove the final .0005” with a 280 grit stone and polish briefly with a 400 grit stone being careful not to burnish the surface.

Surface finish roughness should be between 20 to 30 microinches Ra. Ra is a surface roughness unit that is the arithmetic average of the peaks and valley depths expressed in microinches.

  1. 20-30 microinch average

  2. Uniform cuts in both directions

  3. Cross hatch angle 45°

  4. Clean cuts, free from torn and folded material

  5. Plateau to be ½ to 2/3 of surface

  6. Free of burnish and glaze

  7. Free of imbedded particles

  8. Free of excessive void

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(Lee140FHC) #7

I also used Hastings rings… the oil scraper is MUCH easier to install as it is a one-piece design.

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(Jim XK140 FHC) #8

I have had another email from Grant from a different person. Take your pick .

" Thank you. Of course for any new rings the cylinders should have a clean bore. People still have the misconception from a long time ago when chrome rings were different. Today’s chrome rings are lapped and seat in easier than before. They may take a little longer, but will seat. As long as the bores are in good shape you should be fine."

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(Paul Wigton) #9

That may be true: IME, after about 3000-5000 miLES, on the three disparate engines (BMW, Jaguar, and Datsun) I used them in (all “good” bores, that cleaned up well with a ball of stone hone), all three smoked like mad, and had poor leak downs.

Rebuilt with iron rings…perfect.

Try the chromes, and let us know how it goes!

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