Nissan 200SX Club - South Africa

Ran into a bit of a issue on Tuesday, needed to find a way to grind my ring end gaps for the CP Rings... After I asked the engineers to do it, they didn't, they claim it was fine, I measured and it wasn't...

So stuck on the problem I phoned them asked them if they can grind the rings, they said they have never done that, nor do they own a ring grinder... Phoned around all the tool shops no-one knew or had a ring grinder in stock...

Then I followed WidowMaker's advice and DIY'd it...




I must say it worked like a bomb! Left a very smooth finish!

Some Tips, if you ever have to do this, be very carefull with the 2nd ring, that thing is blerry soft, The first 2nd ring I grinded I only touched it a little and went to measure and it was on spec! By Luck!

Top ring is a bitch, they are damn hard and on average I took 3/5 tries to get them on spec

Oil rings required a min of 0.15" gap some was already on the min some was below Well made them all 0.15" for the sake of being precise

Didn't really have time to assemble much last night, only waterpump

PS: Also had a visit from KimiG and his dad, very nice guys![/img]

PSS: If you need some info on ring grinding... http://www.teglerizer.com/triumphstuff/75w_newrings.htm

is that a dremel tool that youre trying to hide from us? *drool*

Yip... Good News is that Builders Warehouse started stocking them... The tool it self is decently priced, but the cutting disks are kak expensive...

what the hell is 0.15"????

stoopid imperialisticalism!!!!

yeah since the CP pistons are from the US... all measurements are in inches...

Why do the engineers not grind rings? Maybe they have a valid reason? Like maybe the rings are specially treated on the outside to withstand heat, and you've just grinded off their protective coating? Make 100% sure otherwise you'll have another rebuild on your hands...

Toby wrote:Why do the engineers not grind rings? Maybe they have a valid reason? Like maybe the rings are specially treated on the outside to withstand heat, and you've just grinded off their protective coating? Make 100% sure otherwise you'll have another rebuild on your hands...

hehehe you may be pushing it alittle this time toby

No no Tobles... Ring end gaps is the gap between the opening of the ring, remembered when we measured that gap with the feeler gauge... now that gap needs to be a specific minimum otherwize when the rings heats up the gaps will touch causing ring to scrape into the bore...

No I'm close to 100% sure I've done the correct thing, the reason why the engineers didn't grind the rings is that their calculations was wrong

See it works like this

Bore x 0.007" = Ring Gap

So

3.307" * 0.0065" = 0.021" Gap

What they did was they only took the 0.007" in account and measured that, never did the calculation, the gap before I grinded was 0.011", they only made sure the 0.007" feeler gauge went in there easily. The reason I know this is that they scribbled on that pamphlet

Vlade wrote:No no Tobles... Ring end caps is the cap between the opening of the ring, remembered when we measured that cap with the feeler gauge... now that cap needs to be a specific minimum otherwize when the rings heats up the caps will touch causing ring to scrape into the bore...

No I'm close to 100% sure I've done the correct thing, the reason why the engineers didn't grind the rings is that their calculations was wrong

See it works like this

Bore x 0.007" = Ring Cap

So

3.307" * 0.0065" = 0.021" Cap

What they did was they only took the 0.007" in account and measured that, never did the calculation, the cap before I grinded was 0.011", they only made sure the 0.007" feeler gauge went in there easily. The reason I know this is that they scribbled on that pamphlet

Is your C mixed with your G?

Its GAP not CAP

naaah there was a problem between my keyboard and my chair... Thanx

Vlade, I fully understand why you are doing the grinding (i.e. the gap size). My concern is that maybe the "ends" of the piston ring (as well as the rest of the ring) is specially treated (think of it like a coat of paint). By grinding the ends, you remove this coat, thus exposing the inner metal to the cylinder heat & chemicals. Maybe over time the metal corrodes or something? I'm just asking - I have no clue if this is the case or not.

Aaaah ok, Nah I think it should be fine since the pamphlet that comes with the pistons & rings say one have to check the gap size and gives one some pointers when grinding them... When you come around again I must show you...

That reminds me I actually need to borrow a 3/4" to 1/2" drive converter from you my Little MasterCraft socket set doesn't have one.

BTW Guys check this out, invaluable information when building engines http://forums.evans-tuning.com/viewtopi ... gine+build

Toby no that is not the case, the rings need to be ground in order to get a complete seal, they dont cover the rings in anyway. You do get ceramic coated top rings but then they come pregapped and they dont need grinding.

Vlade my only objection to your handy tool it you are left with an ever so small gap because of the thickness of the grinding wheel. I prefer the ones where you grind one side then the other, that way you can get a perfect seal.

Toby,

Gapping rings isnt a "nice to have", its a must!

The thing is you will never get a perfect seal... Even a professional tool like Calibrator had didn't even make the grinded surface as smooth as my tool, mine is also a lot more square... The only reason why mine is smoother is because it runs at 10rpm where he used a hand tool... both equally effective.