Trying to find more info on the web and without correct keywords I havent had any luck.

- Measure the compression height of the same piston/rod assembly in each hole to find out the total variations compression heights due to the deck variations AND the crank variations.
- Then, put all of the piston/rod assemblies 1 at a time into the same hole, and measure the compression height variations. This 2nd step allows you to ID the variation in length due to JUST the variations in rods and pistons.
- Once you have both sets of data, then:
-- You marry up the shortest piston/rod assembly(lowest compression height found in step 2) to the hole that gave the tallest compression height in step 1.
-- And then the tallest piston/rod assembly can be married to the hole that gave the lowest compression height in step 1.
--Then you try to match the intermediate compression height piston/rod assemblies into the middle height holes.

This is all to to try the get the compression height variations minimized. If the total compression height variations are down to .005" versus a .010" overall compression height variation, then you have decreased the compression ratio variation by about .1 point. You won't feel this in engine operation or performance directly, BUT it allows you set the quench gap more closely and accurately IF you have closed chamber heads, and you want to optimize quench and its improvements in detonation resistance.


And can this procedure be used on Big Block Mopar. Im thinking not since Im reading that all B/RB engines had a piston pin that was offset too make the engines quieter upon start-up in cold weather unlike the small blocks I guess?

yes, alot of pistons are offset. Quench is very beneficial & keep tabs on SCR. United machine & others have good calculators

Or you assemble the engine, measure the heights, and then adjust if needed.

I presume that you are going through the same level of effort to equalize the combustion chambers.

Yes that is correct

It sounds like you have it all planned out, why does it matter what you call it?

I keep a notebook of engine building procedures as I pick them up, the page deserves a title. It also helps research on the net to see other peoples results and their own procedures

The correct name for this procedure is "a lot of trouble for nothing".

1) a properly decked block should have ZERO variation.
2) quality pistons - likewise
3) quality rods - likewise
4) quality crank - same deal

Of the four items I would think the crank would be the most likely to be off. But assuming everything else is equal, what are you going to do about it?

And do you really have to assemble everything first ... pistons and rods can definitely be measured individually with a mic or vernier.

If you have a decent set of dial calipers or a good miikecrometer with a ball end measure the piston pin to the piston decks first and write that down, once you check all four corners with the same rod and piston to determine block deck height variance in relation to the same piston and rod then install the other seven and find out how much variances you see on them.
You really need a four inch stroke dial indicator to accurately measure the stroke differences on each rod journal on any non stroker BB Mopar motor
I think you will find most of the variances in the deck heights will be in the stock rod lengths
I've seen .017 differences in rod lengths with the same forging numbers from mixed rods from different RB motors
I've also seen .020 stroke differences on a crank that had been welded and repaired from a spun rod bearing
BTW, is the name your trying to think of called "engine blue printing" ?
Good luck on your venture for information

"Blueprinting" ??

hi
that is called piston grading !

service manuel for cummins recomends it for the 5.9 diesel

Ok great, I appreciate the info

Very interesting and useful, thanks