Doug's EA81 Rebuild stuff.

Subydoug · Post by **Subydoug** » Fri Nov 08, 2013 10:14 pm

Around 2500km's. Il pull the pistons tomorrow and measure it all up again. I did measure it before I reassembled it and was happy with it. Wasnt the closest of tolerances but It wasnt sloppy either. Hoping I find something like an oil control ring hopped over one ridge or something like that. We shall see.

Regards

Doug

Subydoug · Post by **Subydoug** » Sat Nov 09, 2013 12:38 pm

OK, pistons out, went and got myself a brand new 3-4inch micrometer and bore gauge thingy, here you go, first number is horizontal, second vertical.

Cyl #1
TDC = 3623, 3623
BDC = 2623, 3625
Piston = , 3619

Cyl #2
TDC = 3623, 3625
BDC = 3622, 3625
Piston = , 3619

Cyl #3
TDC = 3625, 3626
BDC = 3623, 3626
Piston = , 3620

Cyl #4
TDC = 3623, 3625
BDC = 3622, 3623
Piston = , 3619

Now, please take these measurements with a pinch of salt. I dont exactly do this all the time and I dont claim to be good at measuring bores. I do feel that I did it reasonably consistantly though. If anything, those measurements will be slightly oversize but not by much. I rounded to the nearest thou. When I measured the bores before I remember When I measured it and when the mech measured it we both got different readings by a thou or two. cant remember exactly.

Its probably due for rebore, and If I remember correctly I had this discussion with the mechanic when I first measured the bores. We both came to the consensus that for daily use it would probably be fine.

Well Paul, give us your two cents Mate, leaving it for a bit to think about.

Now shes apart again, good excuse to get that cam reground

Regards

Doug

Subydoug · Post by **Subydoug** » Sat Nov 09, 2013 4:19 pm

Broken oil ring in cylinder 2.

I guess I broke it putting it in. Relieved I actually found something broken

. Oh well, going over the other's now.

Regards

Doug

steptoe · Post by **steptoe** » Sat Nov 09, 2013 5:33 pm

And go the WRX 2.0 litre pistons and bushings Ivans imports talks of on USMB for EA82's.

Not sure if WRX pistons are for NA EA's or boosted though, you'd need to check with him

RSR 555 · Post by **RSR 555** » Sat Nov 09, 2013 10:19 pm

Well that will do it.. no tension on your oil rings. I'd still look at machine honing up to oversized but this EJ20 pistons might be something to look into, as these talk about bore size of 3622, so would help out but I'd need to check deck, skirt and pin heights.

RSR 555 · Post by **RSR 555** » Sat Nov 09, 2013 10:22 pm

Hey Doug, have you got a pic of that piston looking from the top, so I can see the rings exposed from there grooves?

Subydoug · Post by **Subydoug** » Sat Nov 09, 2013 11:12 pm

I think Il just put it back together with the new rings. Ran fine. If it craps the bed Il get it rebored. That way I get something out of my new rings and pistons. Isnt exactly hard to pull it apart.

WRX pistons sounds interesting, but I though they were a 92mm bore too? Isnt that the same boat?

Paul, Ive pulled all the rings off the pistons to clean the ring grooves up, so no pic. Are you interested in the compression rings or the oil rings? tell us which and Il put them back on for a kodak moment.

Regards

Doug

RSR 555 · Post by **RSR 555** » Sun Nov 10, 2013 8:28 am

Yeah Doug, just put back together with new oil rings for now.. I was thinking further down the track.. like for the SA trip

So these were new pistons? (I'm sure you have mentioned but you know my memory) as you mentioned these are 3619, so there's 3 thou difference between them. I don't have the WSM with me and cannot remember what the piston to bore clearence should be??

No need to refit the rings, I was just looking at the colour of the compression rings and wanted to see if they ok. Have you got them in order of which piston you pulled them off? and can I see the tops of both 1st and 2nd rings off #2 and #4 cylinders please?

Subydoug · Post by **Subydoug** » Sun Nov 10, 2013 9:24 am

Mmmmmmm, I think I can cook up an engine for the trip to SA. No problems at all.

WSM says standard piston to bore clearance is 0.4 to 1.6 thou, limit is 2.4 thou. Like I said though My measurements are most likely oversize because of the nature of the tool I used to gauge it(dont get much feel until she's draging) and the fact I rounded to the nearest thou. I was just happy they seemed consistent, and you were right, cyl 3 is the biggest!

I was happy how it ran. Still flogged the nipples off a particular L series the other day

Just think of what she'd do with all 4 pots working properly

.

Cyl 2 compression ring #1

ring #2

Cyl 4 compression ring #1

Ring 2

Not the greatest photos. I actually cleaned the pistons and rings when I was looking for more broken rings so they look pretty much brand new.

Regards

Doug

RSR 555 · Post by **RSR 555** » Sun Nov 10, 2013 1:22 pm

Subydoug wrote:Mmmmmmm, I think I can cook up an engine for the trip to SA. No problems at all.

I hope so, as it will be a long trip and don't want you to be towing a 44 gallon drum of oil around with ya

Subydoug wrote:WSM says standard piston to bore clearance is 0.4 to 1.6 thou, limit is 2.4 thou. Like I said though My measurements are most likely oversize because of the nature of the tool I used to gauge it(dont get much feel until she's draging) and the fact I rounded to the nearest thou. I was just happy they seemed consistent, and you were right, cyl 3 is the biggest!

Yeah, 1 to 2 thou clearance sounds right and yours is well above that, so maybe you're ok for around town but I wouldn't be taking to many runs along the beach

Subydoug wrote:I was happy how it ran. Still flogged the nipples off a particular L series the other day Just think of what she'd do with all 4 pots working properly .

She did extremely well for the low profile tyres and I can't wait to see her running on all fours.. both in engine and tyres

Subydoug wrote:Not the greatest photos. I actually cleaned the pistons and rings when I was looking for more broken rings so they look pretty much brand new.

Photos are fine and from these I can see the marks where the rings are slightly twisting due to the piston/bore clearance.

Good to see #3 is the largest as we spoke about, so maybe pull down the original block and maybe use that one for the stock engine and then use this worn one to have the oversize work done to it later? Just my thoughts anyway

Subydoug · Post by **Subydoug** » Sun Nov 10, 2013 2:26 pm

You know what, I think those rings I had in the engine were wrong. I just finished putting the new rings and pistons back inside the motor. The Hasting rings that I got are what were recommended with these pistons. The ring to ring land tollorance is lots closer with these rings and when pushed into the ring groove, they are the same depth(ring squashed right into the groove is flush with outer piston). The other rings were a lot smaller and there was large amounts of carbon built up behind the rings in the ring grooves which I had to remove to even get the rings to fit, or I wouldnt have been able to get it down the bore. Mayhaps that was a contributing factor to some of the blowby? one can only speculate these things. Cant be 100% sure because Im comparing new rings to old here...Who knows. I wish I had measured them before putting it back together

. Il certainly have a better idea in around 1000km's time

. Tell you what Paul, at 2500km's Il whip out one of the front pistons to have a look.

Oh and for reference, ring end gap came out at ~0.3mm for the compression rings. On the larger side of what is acceptable (WSM says 0.2-0.35 STD) but no where near the limit of 1mm.

Well the way I see it now, I have two engines which Im happy with the big end. I have a set of heads that Im happy with. Larger valves from later model engine, shaved to bump up the CR. And one set of bores that would suit a rebore, the other one I speculate could get away with some new rings but Id have to measure the bores in that engine to be sure. Options are limitless

. And eh, lets face it, I like pulling stuff apart too much to be normal

.

Anyhow, pistons are in, heads are on and torqued up. Few hours more and il be turning the key, but not today. Maybe some more later when It cools down a bit but most likely during the week.

Regards

Doug

littlewhiteute · Post by **littlewhiteute** » Sun Nov 10, 2013 5:31 pm

Have you got the correct rings now?

Rings are NOT meant to bottom in the ring lands.

Combustion pressure needs to get behind the ring to help keep it tensioned against the bore.

Subydoug · Post by **Subydoug** » Sun Nov 10, 2013 5:36 pm

These were the recommended rings for these pistons... So I hope so!

littlewhiteute · Post by **littlewhiteute** » Sun Nov 10, 2013 6:14 pm

Some food for thought:

From Ross Racing Pistons:

Side (or lateral) clearance is the measurement of the space between the sides of the piston groove and the ring. Unless otherwise ordered, ROSS will machine all pistons for a side clearance of .002 to .004. Some engine builders prefer to have us reduce the side clearance (especially with gas ported pistons), however under no circumstances do we recommend less than .001.
Back clearance can best be measured by pushing the ring into the piston ring groove until it bottoms against the root of the groove. The amount that the face of the ring is below the ring lands is the ring back clearance. It should not protrude beyond the lands when the ring is bottomed in the groove. All ROSS compression ring grooves are machined for approximately .004 back clearance unless otherwise ordered. Ross will machine special groove widths or depths at no additional cost.

Subydoug · Post by **Subydoug** » Sun Nov 10, 2013 6:38 pm

Interesting.. I never actually measured it. The old rings would be more like 0.5-1mm. Donno if that's because they had worn all that away... I can only speculate.

Regards

Doug

RSR 555 · Post by **RSR 555** » Mon Nov 11, 2013 9:15 am

Yeah Doug, you need to have clearence between the ring and the ring lands at the bottom of the groove. Correct rings will sit flush with the piston when pulled in tight, these will expand out once inside the bore, which as Gary has mentioned shouldn't be very much. Where I see the issue is the wear in the bore, which by looking at the marks on the rings, tells me the bore is larger than normal. I'm sure it's fine for around the city but not good for high RPM (i.e. beach driving in Low Range).

Also need to check the ring end gap before installing, by putting the compression rings (doing one only at a time) inside the bore starting at the top and working your way down the bore (using the piston to keep it square to the bore) then checking the gap with feeler gauges. Most rings should not need this but best to double check before assembling.

We can tell you love pulling things apart, so keep it up. I find it the best way to learn things

Subydoug · Post by **Subydoug** » Mon Nov 11, 2013 11:36 am

Already checked ring gap. ~ 0.3mm like I mentioned earlier. Yeah should squash back into the ring. What I mean though is the old rings I pulled out would squash in right past flush with the bore. I donno if it wore it all down or it was like that new. Started work early today so il knock off early and finish putting it back together. A compression test after a few hundred km's will tell me exactly what I wanna know.

Doug

RSR 555 · Post by **RSR 555** » Mon Nov 11, 2013 1:25 pm

Ok.. understood

Sounds like they were not the right ones because I couldn't see them wearing out that fast, even with that much oil on them.

You said you fitted new rings, was it just the oil rings or complete new set? If it's a new set, did you give the block a light hone?

Subydoug · Post by **Subydoug** » Mon Nov 11, 2013 3:09 pm

Complete set of hasting's chromoly ones. Yes a very light home in kero, washed until the rags came out clean. Sucked a bit because I had to split the cases but I didn't have much of a choice.

Regards

Doug

RSR 555 · Post by **RSR 555** » Mon Nov 11, 2013 6:31 pm

Sounds good Doug and better to be safe then sorry