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Discussion Starter #1
Hey guys,

Running into an interesting dilemma and been up all night searching websites and forums. I took my 5m block in for inspection, cleaning, etc. Everything came back as standard, no machining needed. I bought some new rods and pistons that were all std as well. Two things: when I try to insert the rods through the top, they are just slightly bigger than the bore of the cylinder (at std). Secondly, I took a piston top to try the same and it also gets hung up at the skirt. Im not even to the rings yet.

I can grab the old pistons and measure them against the new ones, but i just expect it to fit.

Thoughts?
-Brian
 

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Discussion Starter #2
Im just taking the block and pistons to the machine shop. The owner said he's willing to check out what's happening.

Ive never ran into an issue like this in all my rebuilds. Originally I thought my rods were badly manufactured. But with pistons from a whole different brand not fitting, im starting to think block.

Anyone have experience with brands ITM or CXRacing?
 

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Both ITM and CXRacing are generally wholesalers of internal components (neither are original manufacturers for internal parts) and will be more likely to not meet OEM standards. ...if the outer dimensions are off, just imagine how bad it'll be when you find that the inner wrist-pin or rod bearing dimensions aren't quite right either.

Is it possible to return those new components and instead pick up a good used bottom-end with factory crank/rods/pistons and just re-ring/bearing as needed? You'll likely see a much longer service life out of that build than what you have going on there.

--billyM
 

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Discussion Starter #4
Yes its possible. I have all my original 5m rods and pistons still in order. The change was swapping in a 7m crank (for 6M conv). The flange was shaved at the oil pump mount and my new oil pump is also trimmed.

I also have full set of 7m pistons and rods.
 

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What rods and pistons did you get? Sounds like the pistons are 0.5mm overbore. If the rods are h beams, probably require a larger than stock bore. On a m series for example, Pauter rods will not fit unless it is bored out6 at least 1mm.
 
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