E32 750iL Engine Swap & Manual Conversion

[sutekh]

Had a chance to check several main and rod bearing clearances with plastigauge this weekend. All measured within TIS tolerances at just under 0.002". Sending it!

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[sutekh]

After consuming the M70 rebuild manual Shogun posted in another thread (thank you!), I discovered what I believe to be a discrepancy between that publication and the (in?)famous BMW tightening torques PDF. Specifically and per the below attached images, the M70 manual calls for the inclined main bearing cap bolts to be torqued to 34Nm (25ft-lbs), whereas pg.13 of the torque manual appears to call for 20Nm + 45deg. After several tests, 25ft-lbs is (unsurprisingly) significantly less tight.

torque1.pngtorque2.png

My initial reaction was to preference the rebuild manual's guidance, which was specifically authored for the M70 after all, but that ran contrary to my innate "gutentight" proclivities. In the end, after tightening the support sleeves to 7ft-lbs (at least on this point they agree), I tightened 'em to 15ft-lbs + 45deg. Posting this here for posterity.

[moroza]

Glad I'm not the only one who abides by the Gutentight standard I can see ambiguity in the M70 manual; perhaps they intended only the oilpump "consoles" to be 34Nm. Does either manual mention reuse of the bolts? A torque spec that includes an angle usually implies yielding of the bolt, rendering it unreusable.

[sutekh]

Glad I'm not the only one who abides by the Gutentight standard I can see ambiguity in the M70 manual; perhaps they intended only the oilpump "consoles" to be 34Nm. Does either manual mention reuse of the bolts? A torque spec that includes an angle usually implies yielding of the bolt, rendering it unreusable.

They could only be referring to the consoles, but what got me is that they specifically indicate "Install bolts (1) ... and torque with 34Nm". There's only one #1 pictured, but they refer to in in plural. That's admittedly a lot of presumed meaning riding on one "S", but they don't speak to those inclined bolts anywhere else in the manual, so I'm left to assume it's intended to include the other 10 as well.

As you've surmised given the torque-to-yield application, the manual does call for replacement bolts. Given the current cost of each bolt (nearly $10ea!!!), I bought a couple of each and measured the length against those I'd removed. The results were inconclusive, and if they stretch, it certainly isn't consistent or by much. I did, however, reluctantly purchase new ones. I honestly don't think it was necessary, but I wasn't going to risk blowing the motor over a couple hundred bucks in hardware.

[a777fan]

They could only be referring to the consoles, but what got me is that they specifically indicate "Install bolts (1) ... and torque with 34Nm". There's only one #1 pictured, but they refer to in in plural. That's admittedly a lot of presumed meaning riding on one "S", but they don't speak to those inclined bolts anywhere else in the manual, so I'm left to assume it's intended to include the other 10 as well.

As you've surmised given the torque-to-yield application, the manual does call for replacement bolts. Given the current cost of each bolt (nearly $10ea!!!), I bought a couple of each and measured the length against those I'd removed. The results were inconclusive, and if they stretch, it certainly isn't consistent or by much. I did, however, reluctantly purchase new ones. I honestly don't think it was necessary, but I wasn't going to risk blowing the motor over a couple hundred bucks in hardware.

Yeaaaah... glad to hear you got the new ones. I doubt the TTY bolts deform in a scientific enough way to determine if you could re-use them. 10 bucks a bolt though?!? Ouch.


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[moroza]

They do deform in a measurable and predictable way, but manufacturing tolerances wash out the measurements; you'd have to measure the same bolt before and after. For engine internals, I'd've (grudgingly) done the same, probably. For most other applications, and possibly even this one, source quality generic bolts. Is it 07119913673? M8x1.25x35 class 10.9, made by Kamax, nothing apparently special about it.

[Leonator134]

Anything ever happen with this??

Did it end up being the adapter plate was made incorrectly?


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[SergeBMW]

Any updates? I've just given myself the greenlight to go ahead with a manual swap on my E32 750, have to ship the car to myself in the coming month but will be collecting parts in the meantime.

My concern is the adapter plate you had trouble with. I have found that they are made for the E34 420G but don't have absolute confirmation on this. Kaman motors did this but not sure what trans he used.