Need help Inserting piston circlip

[GregMember]

Actually Ollie I reread the last two posts of yours and they didnt really help AB and its the tech thread dept and there are rules please reread them if you dont remember

TB

Back on Topic please

[DeanMember]

Trailboss wrote:

Quote:

Actually Ollie I reread the last two posts of yours and they didnt really help AB and its the tech thread dept and there are rules please reread them if you dont remember

TB

Back on Topic please

Trent Dont be afraid to ask a Dumb Question, best tech advice you can get

The Pins in the piston ring lands are there to prevent the rings rotating, also note that the gaps are staggered to help prevent blowby

Ollie

[TrentMember]

I’m using a CP piston and there was no pins.

I’m pretty sure that the gaps were staggered too though if they weren’t it’d be quite a coincidence.

[PaulMember]

AustBlue I recomend taking it apart and check the ring end gaps are to spec, then follow Mr Blues instructions.
Do not put the rings in a vice to file the ends, put the file in the vice and move the ring over it by hand and do it in the direction that shaves metal away from the ring surface which mates to the cylinder bore.

Personally I like to fit rings & piston with one circlip in, to the barrel then lowering the lot onto the rod.
Keep it all spotless too except for the 2T oil.

[TrentMember]

If my crude measurement got 0.3mm wouldn’t that mean they’re definitely under the 0.8mm maximum? Is there a minimum gap?

Bugger that means I’m back to the beginning! Oh well at least I’m getting plenty of practice with this!

[PaulMember]

Austblue wrote:

Quote:

If my crude measurement got 0.3mm wouldn’t that mean they’re definitely under the 0.8mm maximum? Is there a minimum gap?

Bugger that means I’m back to the beginning! Oh well at least I’m getting plenty of practice with this!

There will be a minimum gap and it cant be any less than that for expansion. It needs to be measured acurately and be close but not less than the minimum gap.

[JasonMember]

Austblue wrote:

Quote:

I’m using a CP piston and there was no pins.

I’m pretty sure that the gaps were staggered too though if they weren’t it’d be quite a coincidence.

That picture you posted has piston clip grooves in it….
As for fitting a clip, use a fine pair of needle nose pliers and all is very easy… :cheer:

[TrentMember]

:angry: It takes me 5 minutes just to get the bloody clips out!

What did you mean by the piston clip grooves? You mean the slot to get the circlip out? I’ll have a look in my manual for the ring end gap specs now :dry:

[TrentMember]

I just checked again and the repair manual is only giving a max end gap for both comp and oil rings being 0.8 and 1.0 respectively. I’ll have to look further!

[PaulMember]

Is there a detailed specs. section in the manual?

[TrentMember]

Yeah nothing on it there though.

[Graeme PattersonMember]

end gap is critical especially if it is too tight. The ends can butt up when it heats up, the gap is to allow for this expansion. Too big of a gap puts you back where you started a lot quicker (rings out of tolerance and compression losses) Some manufacturers have different specs due to use of different materials. most manufacturers call for .004″ for every inch of cylinder size so in this case (has to be converted to inches then back again)
76mm / 25.4 = 2.9921259 inches
2.9921259inches X .004 = .0112 inches (rounded up)
.012inches x 25.4 = .3048mm

BUT
if it is a CP piston set they call for .005″ per inch
76mm / 25.4 = 2.9921259 inches
2.9921259inches X .005 = .015 inches (rounded up)
.015inches x 25.4 = .381mm

check your instruction sheet or their website as some are different and they should also tell you how to adjust the end gap.

If unsure on doing it take your cylinder and ring to your local shop and give them the end gap spec you are after and they might do it for you cheaply as they should be set up to do the job and have a ring grinder.

Most manufacturers also say your cylinder should be torqued down when checking the end gap, but dont know many that actually do this and dont know how much of a difference it makes, maybe someone with more knowledge can tell us all

try here
cp install

[Bruce CurtisMember]

It’s right about heat and expansion as has been mentioned, can break the rings as well if not checked. Patto the bolting down that’s for any cylinder distortion that may show itself when bolted to the cases, and seeing as they don’t machine the barrel on the cases, I have never worried or seen anyone else worry about it.
A ring can be carefully filed with a fine diamond nail file, carefully holding the ring in your fingers as close to the end as you can, and a little filing goes a long way.

BC

[TrentMember]

Thanks. I just checked your link ekips and you’re right so I’ll have to pull the piston and cylinder back off and re-check it and if its no good I’ll take it to the shop tomorrow to get filed. I have no vice or diamond nail file.

[TrentMember]

Mr Blue wrote:

Quote:

Whatever technique of build you use always preoil the wrist pin and bearing

Ring end gap is best done suing an old piston to square the new rings in the barrel.

BC

I just measured using the barrel and the new piston and I got 0.5mm for the compression ring.

By “wrist pin and bearing” do you mean the pin that holds the piston on the conrod and the sleave in the conrod?

[Author]

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