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HEAD REPLACE; PISTON DESIGNATION 02
Topic Started: Oct 3 2017, 05:02 PM (301 Views)
Iconn
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ICONN

This is the second head job I have done on a 1.0 liter. Apparently I had blown head gasket. The tops of the pistons were perfectly steam cleaned off. It was blowing a lot of coolant out of the system when running but the compression was not bad. But my question is what is the "02" stamped on each piston top. Does this mean it has been rebuilt once with overbore at 20 thousandths? Thanks :hmm
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geogonfa
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Just my .02ยข...if you look at the front left (Crank side near the Intake) top of the block there will be 3 stamped numbers in the block, those should match the corresponding pistons in the cylinders...there will also be a direction arrow stamped into the piston top... :type
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Iconn
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ICONN

No this is right in the middle of each piston stamped or marked "02".
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freegeo
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Geogonfa said what it was for. At the factory numbers were stamped on the block and on the pistons. Either a 1 or a 2 was stamped on them. The numbers correspond to a specific measurement. The numbers on the block would represent which cylinder was what size. Example. 1, 2, 2. Cylinder # 1 would take a # 1 piston and cylinders 2 and 3 would take a # 2 piston. The factory did this to keep the piston to cylinder clearances correct.

If the block has ever been mill to get it flat then the numbers on the block may not be there.

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Edited by freegeo, Oct 4 2017, 06:22 PM.
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geogonfa
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Just curious...are you sure it's not a C2? :type
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freegeo
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One of my engines had a A and another had a B on them before the number. The letter could represent a supplier code.
Edited by freegeo, Oct 4 2017, 11:44 PM.
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Iconn
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ICONN

Oh, They must have played mix and match to keep tolerances close without having to do fancy quality control on individual parts. That means you would have to buy rings for each cylinder for the right piston. Interesting. The info of exactly what the number had to do with was not clear. Thanks for the pix and info all. No the block numbers have not been milled off.
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Iconn
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ICONN

By the way if someone has insight on what I should look for please clue me in. This is the first head gasket that I have replaced that was associated with a defect. In this case it was a leak to the coolant. It seems a little corroded in one place but I as expecting a little "track" where the hot gas was spilling to the water jacket. I guess it could be a very small channel almost invisible?
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freegeo
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Iconn
Oct 5 2017, 10:37 PM
Oh, They must have played mix and match to keep tolerances close without having to do fancy quality control on individual parts. That means you would have to buy rings for each cylinder for the right piston. Interesting. The info of exactly what the number had to do with was not clear. Thanks for the pix and info all. No the block numbers have not been milled off.
Here is what the numbers mean. No special rings would be needed.


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Edited by freegeo, Oct 5 2017, 11:36 PM.
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freegeo
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Make sure the block and head surface is flat before reassembling them.
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Dystopiate666
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Tree Banger

:gp

After 2 blown head gaskets I would start double checking for other problems before throwing another one in.


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Iconn
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ICONN

NO the other "blown" head gasket was on a different car. It runs fine now. It did NOT have a blown head gasket. It had a bad valve. This one shows the valves evenly colored. All the cylinders had 170 psi a month ago when checked but the odd thing is that on removing the head everything is pristine clean. I put kerosene in the cylinders and no leakage. I am speculating that water was being sucked into the manifold from a passage and is a defective manifold or something in the head. The engine looks like it was running a little lean and was being steam cleaned internally. In anycase maybe the new head will fix it if it is a water leak in the head. I am going to do more checking for head surface. I notice that the steel sleeves stick up about a thousandth of an inch above the aluminum, enough to catch on a fingernail. I am almost ready to tear apart my spare engine and compare.

Can anyone tell me about milling? Do I need to take the pan off and pistons out? Thanks. Sorry I just have so little experience and have not felt well. Thanks anyone for any help.

Third question. The only gasket I am short on is the one for the distributor housing to head. It has three bolts. I am thinking of making a gasket or using a forma gasket solution. I don't think there should be a clearance problem. Any comments? Thanks
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freegeo
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Quote:
 
but the odd thing is that on removing the head everything is pristine clean.


If every cylinder was clean and no carbon on them then you had some type of coolant leak into each one. It is normal to have maybe 1 or 2 cylinders that way with a blown head gasket but I never have seen all 3.

The head and block surface needs to be checked with a good straight edge and feeler gauge. if you are not sure how to do it I can post the procedure, it is not hard.

If it is not flat then it can be fixed at a machine shop or some people have used a flat board with sand paper to flatten it.

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The only gasket I am short on is the one for the distributor housing to head


Me personally i would use the gasket. Without it, it could cause your distributor to bind up against the end of the cam.
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