waiting on some video footage to see just how much flex she has now but there's plenty more than what this photo shows!

 

Big jump to get out of the drivers seat for the picture!

 

Hello everyone. hope all is well! I'm here to ask the world of DII knowledge about piston rings.

I ordered a new set of rings for all 8 pistons for my 2001 Disco II from Atlantic British and I also had top hat liners installed by a professional machine shop (who have done many rovers over the course of 40 years).

All the cylinders are the exact same size (according to my bore measurements) so I put the first and second compression rings into just #3 to check the gap in case i needed to shave it down. To my surprise, I found that the gap appeared to be larger than spec [1st compression ring=0.30to0.50mm (0.012 to 0.02 in). 2nd compression ring=0.40to0.65mm (0.016 to 0.026 in)] by about .01mm for the 1st and .005mm for the 2nd compression ring from about 1 to 1.5 inches into the cylinder.

My thoughts are:
1. Send these rings back (along with the arp bolts that don't fit in the side of the main bearing caps) and get larger rings from somewhere and grind to fit.
2. OR Could it be that since these are meant to expand with heat and it is fairly cold where I am (approximately 30F to 50F overnight and 65F max throughout the day) that the measurements are skewed?
3. Just put 'em in! So what!
4. Could my cheap set of feelers be off?

THANKS for your help people!

 

Thank you.

 

Feeler guage "should" not be that far out, but, find calibrated calipers or a micrometer, or even another set of feeler guages if you are in doubt.
If the bore measures good, and the ring gap is too big, definately send them back.
I just gapped new Allmakes rings from Lucky8 on my 4.6 rebuild.
My bores measure in spec.
Of the 16 compression rings, I had to grind 12, which is not uncommon,(all 24 oil rings were in spec, and the middle one is tough to measure).
So you most definately can buy rings with the correct or smaller and grindable gap.
Those temperatures would not change the size that dramatically either.
Make sure to gap each ring in the cylinder it is going into.
The variance in indvidual piston, ring, and bore size varies enough while still measuring in spec, but can and will vary enough to make a measurable gap difference across different cylinders.
Too tight a gap(which I know isn't the issue), and I'de be concerned about breaking a ring, and rebuilding again.
Too big a gap(if you just "threw them in"), would result in more blow by, performance loss, and shorter life, which would be a shame on a good rebuild, especially with top-hats, and the idea being the engine lasts long term.
Those rings would be considered the right size(because they fit the bore), but just defective, and out of spec, as there's always manufacturing defects, just sometimes it's the customer that finds them.
For the wrong size bolts, yes, exchange them.
Get a new set of rings.
Start again.
Frustrating, sure, but important and worth doing right.

 

I find it quickest and easiest to gap all the rings for each cylinder, put them back in the plastic sleeves(I write the final size on each one), and put them back in their box.
Then do the next til all 8 cylinder's rings are all gapped, and are ready to go on the pistons.
That's a good start and stopping point.
I also always order 10 sets of rings(just me), that way if I break one, find one out of spec, or grind one too much(easy to do), then I have a spare.
It beats stopping a rebuild to order and wait on one or 2 rings.
Doesn't cost alot more, and time is what can be hard to come by.

 

It doesn't work like that. ARP studs don't go into the side of your main bearing caps, and your cylinders aren't the same size... but you don't have to take my word for it, you can test it without any measurement tools.

Simply lay one new piston ring on top of one of the piston rings that you removed. Compare.

Also, you never gap piston rings in only one cylinder. The whole point of gapping is to blueprint your piston rings to OEM book specs for each cylinder.

When you are doing your gaps, you only want one new piston ring in the cylinder bore for the piston that will go there... and you want to insure that it is *perfectly* horizontal to the height of the bore (which is easily accomplished by pushing it down into the cylinder bore with a removed, but turned upside down piston that you are holding in your hand).

Oil your new piston ring.
Insert it into your a cylinder bore, say, for #1.
Turn your #1 piston upside down in your hand. Press the top of that piston onto your new piston ring to push it down an inch or so into the #1 cylinder bore.
Lift your #1 piston out of the bore.
Now measure your new piston ring gap.

 

what’s your rear setup?

 

RTE 3" springs with TF +3" adjustable shocks, so roughly 11" of shock travel per side. Relocation cones and spring retainers. This weekend I plan on throwing 1" spacers back in the rear just to level things out a little more. I plan on picking up a RTE extended watts linkage this spring hopefully. Oh and no sway bar and extended brake lines. The tire will tuck up inside fender, pic for reference on old worn out springs.

 

hey thanks for the reply! ARP makes a bolt set for the main bearing caps. They aren’t studs, but they also didn’t fit. Lol. The side bolts are a good inch shorter than the original. I did everything above and planned on measuring in different cylinders, but I still don’t understand how that helps if all the rings are the same size (per 1st, 2nd compression, and oil). Wouldn’t that mean, at this point, that I’d have at least one cylinder (#3) where the ring gap is too large?