Dan87951

Can you post a picture of the different pistons? I'm curious to see what's in there.

Mrmerlin

Sean, heads removed with the engine in place
piston pictures.

NOTE the pistons with the small numbers on them are all on the 5678 side of the block
NOTE the center lower stud on the 5-8 side is slightly bent to the rear ,
I am not crazy about the suds,
some have corrosion

FBIII

Are there two different size pistons in the engine? O's and 1's? Or am I misinterpreting the numbers.

Mrmerlin

Did I mention Colin flew in to do some other work and see the car his take is.

there are actually 3 different sizes and the block is a #1 tolerance code
the 1 and 3 piston are PLUS+
the 2 and 4 are 1
the 5 thru 8 are 0
the 4 pistons on the driver side are too small
all of them are burning oil as seen by the black carbon deposits.
the bores in 6 and 7 need to have sunnen paste treatment to restore the silicone finish
Cuing Andrew Olsen

I need 4 4.7 Euro pistons from an 85 tolerance group 1

GlenL

What's a "plus" size?

Did you measure the pistons and bores? Has the engine been apart to get the small pistons in there?

Mrmerlin

the block is still in the engine bay ,
and the pan is on it.
none of the pistons have been removed .

I would like to know who would add smaller pistons like this.

GlenL

I can't make out the stampings on the block. So those don't match the pistions in the holes?

Mrmerlin

the block is all tolerance code 1 ,
every hole has a one stamped on the piston code pad

KenRudd

I am not staring at an engine right now, so indulge me if this is a dumb question, but where is the "piston code pad"?

Mrmerlin

it at the top edge of the piston bore there is a small pad with a number its in the center line of each bore

Mrmerlin

funny thing look at the specifications in the WSM and see how small the differences are between a 0 and a 1 piston,
The Germans making sure that a piston will not stick
after its working.
bottom line measure the bore and piston see whats going on.

Mrmerlin

Ok so what is it with wood ruff key ways and these older cars and me working on them.

I know when I needed a puller to remove the new oil pump pulley from its shaft that things were amiss, after sighting in the gouges on the pump shaft, guess what was next.

DOH clearly this was not its finest hour,
the crank wood ruff key was buggered up ,
as well as lots of gouges and marks on the crank snout adjacent to it.

I first tried some heat and ice on the key,
then some gentle persuasion with a chisel and mallet.
Haa it was laughing at me,
I drilled a few holes in the key and it laughed harder
So I kept talking to it.

The dremel came in handy for cutting a groove on each side of the key,
after about an hour of cutting it finally started to listen to me.
Finally its out time to dress the crank. and the cutout.

Mrmerlin

I found a set of Pistons these look different than the ones in the engine I have,
the valve reliefs are very deep
http://www.ebay.com/itm/262416778520?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

BRB-83-911SC

My 84 Euro has the pistons with the larger valve reliefs. For the Euro 4.7L 16V motors, I believe that sometime mid 1984 production a switch was made to the smaller relief pistons giving a true 10.4:1 CR. The larger relief pistons were used in the 4.7L Euro S CIS motors, and early 84 Euro S LH motors, yielding a 10.0:1 CR. (as I recall from earlier discussions) So, an 85 Euro should have the smaller valve reliefs. Since these (smaller valve reliefs) were specific to later 84 and up 16V Euros, I suspect they will be hard to come by in the US.

Mrmerlin

well thanks for the enlightening information,
I guess its just a re ring if the bore spec is good.
Oh and a Sonnen silicone paste Hone job