5.2 Build - main bearing size code identification

[GregO]

It’s nerve wracking but I measured each main in 3 locations and averaged them:

1. 2.8512
2. 2.8515
3. 2.8516
4. 2.8515
5. 2.8510

It’s not aligning with any Ford pin stamped letters is it ?

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[K4fxd]

I don't see a 15 or 16 on the chart

 

[engineermike]

Thermal expansion can account for 1/2-1 mil pretty easily. That’s why I said I was more concerned with the relative values not the absolute number.

 

[K4fxd]

Is it specified they are hot numbers? I would assume cold on a crank journal.

 

[engineermike]

Is it specified they are hot numbers? I would assume cold on a crank journal.

Just 10 deg f difference can be half a mil, so if the ford measurements were at 70 and I did it at 80 then there’s your difference. However I don’t know the ford standard temp, nor do I know if they use one, three, or six measurements to average. This is why I’m not going to worry with the difference in absolute value but rather focus on the relative values.

 

[GregO]

Now to measure the crank @ 80 deg F.

 

[WildHorse]

American engines: Loose tolerances. European engines: Exact tolerances.
This is why American engines far outlast European engines.

 

[engineermike]

Now to measure the crank @ 80 deg F.

Doesn’t really matter because I don’t know the bearing shell thicknesses anyway. The point of the exercise was to determine which ford code is the correct one and order bearings as such.

@WildHorse you know the gen3 piston to bore clearance low tolerance actually puts the clearance in the negatives.

 

[WildHorse]

you know the gen3 piston to bore clearance low tolerance actually puts the clearance in the negatives.

Must be magic.

 

[K4fxd]

The coyote main bearing clearance rounded up is .01 to .02 inch

I wouldn't call that loose.

OOPS forgot a zero.
.001 to .002 inch

 

[GregO]

Doesn’t really matter because I don’t know the bearing shell thicknesses anyway. The point of the exercise was to determine which ford code is the correct one and order bearings as such.

I guess I need this explained to me.
The bearing chart requires both block main diameter letter code (horizontal line #2) and crank main journal letter code (vertical line #1) to determine bearing grade ?

 

[WildHorse]

I wouldn't call that loose.

Call it whatever the hell you want.

 

[K4fxd]

Call it whatever the hell you want.

Generally oil clearance is determined by journal diameter.

 

[engineermike]

I guess I need this explained to me.
The bearing chart requires both block main diameter letter code (horizontal line #2) and crank main journal letter code (vertical line #1) to determine bearing grade ?

The question I’m trying to answer is whether INNMG or AUDDA is the right code for this block. I’m not worried about the actual clearance yet. I knew before I took measurements that I probably wouldn’t be able to replicate ford’s because I don’t know their standard or procedure, but I could probably establish precise enough (even if not accurate) to determine which string is the right one to use.

 

[GregO]

The question I’m trying to answer is whether INNMG or AUDDA is the right code for this block. I’m not worried about the actual clearance yet. I knew before I took measurements that I probably wouldn’t be able to replicate ford’s because I don’t know their standard or procedure, but I could probably establish precise enough (even if not accurate) to determine which string is the right one to use.

Fair enough.
Just to ramble on a bit. I’ve seen modern ISO OEM’s using fully enclosed walk in CNC climate controlled structures in the PD pump industry. Parts are brought in and sit 24 hours before machining, after rough machining the parts sit another 24 hours to relax before final finish pass. After all that the parts are taken to climate controlled QC and sit another 24 hours where measuring is done with certified calibrated equipment. All that just for sanitary PD pumps….. SPX Flow Delavan WI.
I’d imagine Ford is on par with the above SOP if they’re splitting hairs at .0000

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