I posted something similar in the C4 Tech section, but I felt it should also go here.
I am building a ZZ4 short block that came assembled with pistons, rods and crank. I pulled all these out to have it balanced. More information on the balance at a later date.
We I built my first 350 years ago, the machine shop told that even though the cylinder walls looked clean, to take toilet paper and wet it down with ATF and keep doing so until the TP was no longer black or gray. Well I did that with my brand new ZZ4 short block after I pulled the pistons. Black!! I didn't take pictures, but should have.
I got to thinking today that the lifter holes were probably in the same condition as the cylinder walls. Well this time I have a picture of the results! Here is a picture of a single wipe of the interior of the lifter holes with TP and ATF. I threw a couple away when I first started and then kept the rest for the picture. The one piece that is horizontal is the final cleaning results on one hole.
And this is a brand new GM short block! And you thought it was clean.
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1985 Coup -ZZ4 balanced, LPE 74211 cam, AFR 180 heads, SuperRam base, runners & plenum, cut out air box, K & N filter, power coupler, 52MM TB, March pulleys, AFPR, Accel injectors, Walbro FP, 1.6 RR, chip by TJWONG, 160 stat, cut back plugs, 8.5MM MSD wires, Brute Thunder Coil, custom camber-brace,TRANSGO shift kit, 2400 stall converter, cross drilled rotors, SS brake lines, VBP camber rods, IAS Edelbrock shocks, custom crossover on exhaust, Magnflow cat, 3.07 gears, 13.2 @107.2 MPH in 1/4
What you are removing is the grit left over from the honing process that is embedded in the block - not unusual for a mass-produced block. Taking the time to remove this material before the engine is fired up is just another step in the custom engine building process. BTW, David Vizard recommends removing the grit from the piston bores in the following manner:
"If you want to reduce piston and ring friction and the time it takes to break-in the engine, try this for a torque-enhancing move. Use a Scotchbrite pan-scouring pad to polish the rings until they feel smooth and slippery to the touch. Next, use a pad on the bores in a vertical motion, and use Gunk engine cleaner as a lube. Continue the vertical polishing until the bores feel really slippery. This action takes out a minimal amount of metal and removes or smooths the microscopic tears left behind by the honing process. In effect, this process is similar to a fine plateau honing job."
Nothing to worry about providing there arent any metal chips in there. Any type of dust cast iron related will be black.
Recently flushed out the water jackets on a Dart block and was shocked at how much metal shavings and large shards of metal I got out of there from the machine punching out the freeze plug holes.
Never assume its all clean, always double check EVERYTHING.
Not assembly lube. I ran a clean finger around the hole first and where was not sign of color, just a light oil. When I pulled the thing apart for balancing, I never found any sign of assembly lube, just oil.
Corvette Store
Is your new block really clean?
