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Important Notes on Cummins plus-minus bolt torque values

Diesel engine manuals and specifications 
at Barrington Diesel Club


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Basic specs are open to everyone and include images, displacement, dimensions and weight, essential bolt tightening torques, the characteristics of the engine like its power and torque.
Essential bolt tightening torques are the main bearing cap bolt torque, the connecting rod cap bolt torque and the cylinder head bolt torques.


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Cummins plus-minus bolt torques

Care with Plus-Minus (+-) torque values

Cautionary Note - Cummins plus-minus torque values does not mean approximate!:
The torque procedure for the Cummins N14 connecting rod bolts ends with a +- value of 5°

Essentially, the reason for this is that this value is meant to be tested against a known torque. In the case of this particular bolt the test torque value is 205 lb.ft, 275 Nm.

If the torque of 205 lb.ft (275 Nm) is achieved within 5° of the 60° angle asked for then everything is fine. If you exceed that window, then it means that the bolt has stretched and you must replace it or face a possible connecting rod failure, even a hole in the block!

For this application Cummins has designed a special socket, Part Number 3824520, exactly for this purpose. Current US retail price about $85.

Image - Cummins torque angle gauge socket, 3824520
Cummins N14 
torque angle gauge socket 
Part Number 3824520 

Suggestions:
Some of the later manuals have many of these +- degree values, and they must be taken seriously.

Perhaps when faced with a series of such torques, use a torque wrench to pull your degrees and note every torque value for every degree setting, then you can establish a base average.

Bolts that reach their degree setting at less than 5% of that base average are suspect and should be replaced, especially for the like of connecting rod bolts.




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email: steve@barringtondieselclub.co.za
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