1Z Piston Protrusion / Deck Woes (with pics!)

[twentyeight]

So I'm rebuilding a 1Z with new .5mm over ALH pistons. Initial piston protrusion was about 0.030" which is well under the minimum spec. So I had the block decked 0.007" to hopefully hit right about the middle of a one-hole head gasket.

Unfortunately I got the block back today and the measurements don't look good.
They're listed here: in slightly prettier form, but from #1 to #4: 0.035, 0.036, 0.043 0.047. On all pistons, the pulley side measures lower than the other side—*#4 measures somewhere about 0.052".

I haven't gone back to the shop yet because I don't know what to ask for. If the deck has to be cut again flat, 0.052" is over spec for a 3-hole gasket. My first plan is to take it somewhere else that can measure piston protrusion more accurately before I disassemble it again and take it back.

Does this look usable still?

 

[Yblocker]

Was the initial 0.030" pretty consistent on all 4? Did you measure that initial protrusion? Are your pistons rocking in the bore now? What is your concern on the head bolt holes? I do see there is more material on one of them- still proud of the chamfer as compared to the other two. You might consider contacting Franko6 for some expert help on this. I know he routinely recommends that .007 to .008 block decking when using the shorter ALH piston.

 

[twentyeight]

The initial 0.030 was pretty consistent, yes.

My concern with the head bolt holes is that, to me, it looks like the deck is crooked. The cylinders exhibit the same situation—*#1 has a very slight chamfer where #4 has almost no chamfer at all.

The pistons do rock slightly in the bores. Measuring front to back (perpendicular to the wrist pin) I can get a measurement 0.005" higher by pushing on the piston. Sticking my dial indicator on the rear of the block (as in above the rear main on #4) I think I can get 0.010" left to right (!) but I'm not sure how accurate my measurement is.

Measurements in line with the wrist pin (two per cylinder) look like this plotted:

To me that looks like not only is the deck crooked, but the holes were punched out crooked as well. I'm just trying to gather solid evidence (and be sure myself) before I ask them for a new block.