109 short block wizards only................

[SideSlip]

I removed the pistons from my 109 '87 block to check the rings, and I made a fatal error...............I mixed them up.

Did the factory put any mark on the pistons or rods to match which cylinder they came from? Please help.........a full balance will cost a fortune. Was a full rotating assembly (crank, rods, pistons and flex plate) balance even done at the factory????........or was only the crank balanced? Thanks.

 

[LikeMy6]

Not to worry, there is no special balance job done.The assembly is externally balanced all rods and pistons are the same you should find small dimples in the tops of the stock pistons that will need to be installed toward the front of the block. thats it.

 

[steve hughes]

Not all but alot of 3.8's i've torn apart had the rods numbered. If they are it would be on the small flat face facing outward or on the same side as the bearing tang on the cap and rod.

 

[SideSlip]

I actually noticed letters, not numbers on the small flat face where the cap and rod meet. They're lettered A on one set, then B on the next rod and cap set and so on. Would these letters represent the cylinder number. A for #1, B for #2.......etc?????

 

[FJM568]

I'm not sure on the A and B thing you've got...

Do the pistons have a number stamped on top??? Like 020, 030, or maybe 20, 30??? If so, then the motor has been rebuilt before and the number means the oversize that the pistons are...Then the A, B, C, etc thing would represent which cyl it is, but how the engine builder/machine shop did it is up to them...

The pistons/rods are different from driver's side to passenger side...Not really different, but installed different, meaning offset one way or the other depending on which cyl it goes to...Most pistons I've seen have either an arrow somewhere on the top side of the piston above the pin that when installed in the motor would point to the front of the block or a notch or two in the top instead of an arrow that means the same thing...

 

[SideSlip]

The engine is an original............with only 30,000 miles. But it does have letters stamped on the side of the caps. It is not a rebuild. Anyone know if the letters stamped on the cap sides refer to the cylinder??? Anyone???

 

[LikeMy6]

sideslip I cant comment on the letter issue, but like I said above there is no special balance work done to these assemblies! just make sure you install the rods w/t the offset in the right direction and look for a notch or dimple in the top of the stock pistons,this shows what side of the piston faces the front of the block. Thats all!! Why would you tear down a original 30000 mi motor for anyways?? these motors are VERY simple just take your time. and since you have it apart you might as well install new rod&main bearings and new rings.