IDing EA82 blocks

[Quidam]

@ Quidam,

 

The piston to deck height you mentioned is apparent in these two engines, I didn't mention that earlier.

The '88 dished pistons do sit below the deck some, where the '92 pistons seem to be more flush with the deck.

I have no real way to measure the difference.

 

Kinda wondering now, what the pistons in the two ER27's I have here look like........ I recall reading on here, or the XT6 site, that those pistons are the same as the SPFI EA82 pistons as far as comp ratio goes, 9.5-1.

You could just use feeler gages with the piston at TDC. Or put a straight edge across the bore an measure the gap. I use a dial caliper and the depth gague feature of it. Would be interesting what that gap is.

 

Yes, the SPFI pistons sit pretty much flush with the deck. In fact before I tore this one down:

 

I put heat to the two dowels and pulled them. I put 80 grit on a sanding block and cleaned the whole deck off, rotated the pistons and hit them with it too. Zero deck.

[Quidam]

Aftermarket piston for EA82T 1.00mm oversize

 

 

Uploaded with ImageShack.us

ATSUGI Genuine Subaru EA82T piston.

 

EA81 flat top on a surfaced EA82 block.

Edited October 24, 2013 by Quidam

[TomRhere]

You could just use feeler gages with the piston at TDC. Or put a straight edge across the bore an measure the gap. I use a dial caliper and the depth gague feature of it. Would be interesting what that gap is.

 

Yes, the SPFI pistons sit pretty much flush with the deck. In fact before I tore this one down:

 

I put heat to the two dowels and pulled them. I put 80 grit on a sanding block and cleaned the whole deck off, rotated the pistons and hit them with it too. Zero deck.

Now, those pistons look like the 92 pistons I have, just from the tops.

I still have one piston in the 92 block, stopped pulling them when I found the cracked skirt. I can put a piston back in the 88 block, see if I can get a decent measurement between them. Do know the deference between the 2 as far as deck height was quite apparent, as in .075-.100  or so, just looking at them by eye. The 88's sat lower in the bore.

[Gloyale]

Got a few EA82 engines here, most are disassembled. Got them thru various trips to Members houses.

 

I have what I believe to be 2 carbed blocks, and I'm fairly sure in that deduction.

 

Currently in process of cleaning another block up for reseal and install in my Wagon. But I'm thinking it might be a Turbo block vs. an SPFI block that I was thinking it was.

 

Here's pic of the piston top;

 

 

Besides the squarish dish in the piston top, the bung for the knock sensor is tapped. That makes me think it's a Turbo block.

 

Am I correct on that thought? Only seen one Turbo engine, and that's been some 6-7 years ago.

 

I'm thinking this is an early SPFI block.  Like from an 86, 2wd non-turbo GL. 

 

First off, there is no arrow desingnating which direction is front.  that means these are not offset wristpin pistons.  That puts them in 85-86 ranges.

 

And SPFI would on;y be in 86 and would be 9.5:1 compression vs. 9.0 carbed.

 

My best guess.....but definately not offset so pre-87 for sure.

 

Also, all EA82 blocks are threaded for knock sensor.....look closely.

Edited October 26, 2013 by Gloyale

[Gloyale]

More tidbits.

 

Comparing pictures of pistons in the various years FSMs I found that the pistons with the longer skirt, and more of a "squared" shape to the cutout under the wristpin, match the description of 85,86 sedan/wagons and 87 MPFI non-turbo XT.

 

All the non-turbo pistons 87+ are shorter skirt (20 mm) and have a more curved profile under the wristpin, as well as being offset wristpins with arrows indicating left or right side of engine.

 

 

Soooo.....since there is no vent/baffle on the back of block, we can assume it's not an XT block.  Must be 85 or 86 N/A either carb or SPFI.

 

 

Now to get weird.

 

85 FSM shows 2 different compression ratio for carbed cars. 9.0 and 9.5  both using the same cams.

 

The 9.0 was in all wagons and GL sedans.

 

the 9.5 was only in the DL sedans.

 

 

Then on to 86.

 

Carbed cars......9.0 retaining the same cams as 85.

 

SPFI cars (FWD wagon/sedan) are 9.5, with new cams with longer duration.

 

 

 

'87 Carbed 9.0, SPFI 9.5......all using the new SPFI cams, and all offset with arrows.

 

 

Side note*   this use of SPFI cams in the 9.0 carbed is why I set 87 model carbed cars to 20 deg. BTDC timing instead of 8 deg. BTDC like older carbed cars.  I think Fuji was doing away with carbs, and didn't bother adjusting the timing spec with the new cams.

[TomRhere]

I 1st read Gloyale's postings this morning before I had my 1st cup of coffee down. Made my brain hurt. 

Reread it a few minutes ago, kinda understand it all now.

 

I've looked at all of the EA82's here, 2 are known carbed, 2 SPFI. All of them have threads for the knock sensor, cleaning the gunk out of the bore helps one to see that.

 

edited for correct info;

The 2 carb blocks, and the one that was in the '92 Wagon, have a bore for where the extra case vent on a MPFI would be, but they are not completely thru. The '88 SPFI block just has a bump in the case where that vent would be.

end edit:

 

 

Going with what Gloyale posted about the offset wristpins in the later SPFI engines, my plan of swapping pistons between blocks doesn't seem like a straight forward swap,  without swapping connecting rods and/or cranks also. That will be more money involved for bearings, wasn't planning to do those....

I recall reading on here of people putting SPFI pistons in EA81's, so it does sound doable. Or am I missing something?

 

But then again, I know nothing about the engine as far as mileage and such either. So,, a full rebuild is really, the best way to go.

Edited November 5, 2013 by TomRhere

[Gloyale]

Going with what Gloyale posted about the offset wristpins in the later SPFI engines, my plan of swapping pistons between blocks doesn't seem like a straight forward swap,  without swapping connecting rods and/or cranks also. That will be more money involved for bearings, wasn't planning to do those....

I recall reading on here of people putting SPFI pistons in EA81's, so it does sound doable.

 

You can install the offset pistons with an old crank and vice versa.  The crank and rods are the same only piston changed.  And the pistons can be swapped without splitting the case halves.

 

You just need to make sure if the pistons have arrow......make sure they are pointed forward.

 

I am still baffled about what pistons those may be. They really look like EA82T pistons, but the dish is not nearly deep enough to be those (7.7:1 comp)

 

Perhaps EA81t??? weren't they 8.5 Comp???  They are the only pistons I don't have here to compare.

Edited October 27, 2013 by Gloyale

[TomRhere]

I was under the impression that the rods at least would be different due to the off set. Good to know there's no difference.

[Gloyale]

I was under the impression that the rods at least would be different due to the off set. Good to know there's no difference.

 

Offset is in the piston.  Wristpin hole is offset .5mm to reduce "walking" at the top of the stroke.

[jono]

Jono has been sitting on his pistons for a while, sourced from an engine building parts supply in Lakemba ,Sydney, Australia - Fabre 02.9758.1966

 

TIK # 1S920400

model # EA82T

size 1.00

Parts no. 12006AA240 aha check this gen number !

[nncoolg]

I have a set of genuine (Atsugi) offset EA82T pistons, came out of a rebuilt engine I purchased once, I wish I could find the part number for them, I've even had dealers look and come back with nothing...

Jono, looks like those pistons you've got have the long skirt as well as the strong sides that the offset pistons have, perhaps the best of both worlds, care for some more pics?

[TomRhere]

Pics of the '92 EA82 SPFI engine;

 

 

 

Again, a pic of the EA82 piston top that came with the Wagon, SPFI parts were included, but engine was torn down to the short block.

 

 

Pic of known EA82 carbed piston,

 

 

So 3 different piston tops, 1 is known carb, 1 is known SPFI. 1 is supposed to be SPFI, but I can't prove that, came with the '88 Wagon.

 

I be confused....

 

 

Finally got things needed to measure the piston-deck height on these.

In the order pictured,

'92 SPFI deck is .0

'88 SPFI deck is .028

'85-6 carb is .028

 

And yes, I did get the piston to move in that very rusty cylinder on the carb block.. I was surprised...

[jono]

I knew I had seen a decent discussion on piston differences.

 

Tom, wonder if you can go back and hit edit button ?

 

maybe add a few ^ ^ from keyboard digit 6 pal, some block text, and maybe some spacing to make it easier to digest, even second time around ?

 

Maybe number each pic ? See if it changes everbody's quote window pics ?

 

I have an EA82 block I know to be NA mpfi, has '89 in casting from a wagon I have driven home to part out.

It has the pistons that look the highest comp ratio (not taking into account above or below deck height max)

so, they are not the hugely depressed turbo pistons, and they are not the ones that have two patterns of decompression in them.

Mine have just the one angled depression for valve clearance?

 

Looking at another short block that was from a turbo Vortex, maybe not originally, note its pistons of turbo type shoot a fingernail thickness above the block face - deck . Yet to turn the NA mpfi block to see how they sit in relation to block face .

 

 

Question for Quidam is that EA82 with flat top EA81 piston in your post this page - has it become a runner yet?