Question about standard bore size (A,B,C,D size)

[iTurbo]

Ok you know how the Chrysler 2.2/2.5 block and pistons are stamped with an oversize letter (A,B,C,D)? I know this 'oversize' spec goes out the window when the block is overbored, but what if the block has only been honed? Is it still valid then? I am no machinist, so I thought I would ask.

Recently I put together a all-stock TIII block that was B,C,C,C (1,2,3,4). BUT, I found that the machine shop that had assembled the shortblock originally had mixed up one of them up (C,B,C,C). I have since torn down and reassembled the shortblock with the proper B,C,C,C so the stamps on the block match the letters stamped on the pistons...the block was honed so I could reuse stock pistons though.

Another reason I ask is because I have a nice stock TIII crank/pistons/rods (C,C,C,C)....but no standard bore TIII block. I'm looking for a good standard bore block so I can use them, but I'm unsure if it would be best to find a block that is C,C,C,C or if it really matters?

[iTurbo]

Well great, I just checked all 12 stock TIII pistons I have and ALL of them are 'C'.

[4 l-bodies]

Jeremy,
Each letter only represents about one third of one thousands or .0003. If your using a standard bore block that is used, It will be looser than any that left the factory. Did you measure roundness and taper of bores? I think you will find that they are not nearly as straight as you think they are. What do you have for skirt clearance now?
Todd

[iTurbo]

Hi Todd, I haven't measured anything yet. All I know is I have about a dozen stock TIII pistons, a set of refurbished TIII rods with ARP bolts, and a nice TIII crank that I would like to put to use....but no block. So what this is really about is saving money.. I'm really hoping is to put together a stock TIII shortblock without having to get aftermarket pistons or rods which I already have.

FWDP is parting two low mileage TIII engines so I figure maybe now is the time to get a decent low mileage stock bore block to go with the parts I have *or* is this being too optimistic?

[trannybuster]

Check them with bore mics or telescoping gages...might find everything is still in spec..?...should measure everything up anyhow..good luck.

[OmniLuvr]

i ended up finding a low mileage 94 tbi block to put my t3 pistons in, clearances were still VERY close after the hone, it only needed a light scratching. but i was only building a "t2" not a t3, i had to drill a hole for the turbo return, but im not sure about drilling a hole for the crankcase vent like on a t3 :-/

[iTurbo]

Thanks! That gives me hope that what I'm looking to try will actually work. I'm waiting to hear back from FWDP about the condition of the block.

The block that FWDP is selling is a low-mileage '92 TIII. I have a dozen stock TIII pistons that are all 'C' size. However I'm still not sure if simply honing the cylinders negates this letter specification or not. I can't measure the block myself but it looks like I will be buying a bore gauge soon. I do have a digital caliper though, and I hope that is good enough to measure pistons. Can you tell I'm a newb at engine building? I hope to be pretty darn good at it soon enough though...with all of the forum help.