Need advice on machine shop error on Ford Mod block

[Crazy Dirt]

I suggest doing an experiment with block and torque plate to possibly find out where job went wrong. Install torque plate quickly and immediately measure bores in several areas near middle and top of bore previously circled with a sharpie marker. Record findings. Then let block sit for a couple of hours undisturbed and re measure in same exact spots and compare readings. Iron blocks only creep a little, but aluminum blocks usually move a lot. Letting the block and torque plate settle for a little while helps with accuracy but really kills productivity in a busy environment. The 5.4 block is iron and I've found them to only move a couple tenths in past. Another thing to consider is that 2 people can have very different "feel" with measuring tools and come up with a couple of tenths different reading on same clearances.

Yes, you are right on. When I reinstalled the plates (with MLS gaskets) I waited 10 minutes (grabbed a cup of coffee) and then started measuring down the right bank. The right bank had been torqued for 10 minutes plus the time it took to torque the left bank. By the time I got to #4, I figured I’d made a mistake went back to #1, and in the time it took to measure 2,3,and 4, #1 had moved 2 tenths. I left the block overnight and took the full set of measurements I posted earlier, and checked again at the end of the day. No change between the morning and evening of the 2nd day but you could almost watch the numbers change when it was initially torqued. Not sure how long it took to settle down, just that it was done moving by the next morning. I don’t have a full set of numbers to show during that time immediately after torquing the plates down, but I do remember that one of the bores on the right bank moved 4 tenths within half an hour of torquing. That’s when I put the tools down and called it a day

[smeg]

Can you imagine how much they move when they are running? How much does the middle of the bore expand compared with the deck and the thick bottom of the bore when running? Sort of makes the .0002" max taper seem ridiculous. Also, do they all expand the same amount? Ever heated up a block then measured the bores top to bottom? You might get a surprise.

[modok]

Yeah that requirement is kinda silly...but
A hone WILL get below .0002 taper when working correctly, cutting freely, stroke and stone length correct, ect, just naturally.
If it's not working right, then it won't.
So, I take that to mean, they want it honed right.

[MotionMachine]

A wise man told me once that bores are only round once when using torque plates, it's almost impossible to duplicate exactly the original hone results.

[Momus]

Shouldn't bores be honed pressurised with several thousand psi and at 100 C with a 400 ft/lbs twisting force front to rear?

[modok]

plateuing with a rigid hone VS a brush hone.
plateuing with a rigid hone works great IMO, can further improve the roundness, but has to be done right away.
nevermind running, just sitting around for a length of time....a day say, even just a few hours
the bores will move around enough that it's too late to hone it to a finer finish with a rigid hone. it'll just be all patchy.
So that's why flex hones have their place.

[Crazy Dirt]

What would be informative is to measure a good running engine's clearances.

I would assume that if the running clearance from Mahle is 001" that will be sans coating, at least at the measurement point.

Had a few minutes and decided to indulge this idea a little (only a little, mind you). Had another one of these blocks in the back, but, it has had 110,000 miles (175K) with neglected services put on it. Although, it was apparently still running. I’ll throw in a picture of the pistons. What surprised me was the clearances.

Bores and pistons #7 and 8 were measured. At the points of measurement, there was no coating left on the tops of the ridges milled in the skirt.
#7 measured clearances between 0.0024” and 0.0031”
#8 measured clearances between 0.0022” and 0.0027”
If these had lost 0.001” of combined skirt coating (0.0005” per skirt) like Mahle said can be expected (they are OEM Mahle pistons), that would put the clearances more in the range of:

#7 would have measured around 0.0014” to 0.0021”
#8 would have measured around 0.0012” to 0.0017”

Keep in mind, these clearances don’t yet account for any cylinder or skirt wear. I wouldn’t be surprised if the factory spec was in-fact at the 0.001” “ideal” spec Mahle gave on the phone.