Connecting Rod Assembly problem

[dnadanny1]

Hi there. Sorry that I had put my post under a wrong index of "General Discussion".
And, I really thank you Benz Dr. and ja17 for their input. However, the problem is not yet addressed. Therefore, I would like to move my post to here for more specific input.

I am overhauling  a 1966 M127.981 engine.

As I am reading through the MBEngineSpecs.pdf, it said from 1968 onward, connecting rod bolts are stretch bolts, and I need to install connecting rod cap and torque nuts to 36 ft. lbs, and further tighten an additional 100 degree of wrench rotation.

As the tightening specification suggested the connecting rod bolts should be tightened at 27 ft. lbs, it confuse me that should I add 100 degree of wrench rotation to 36 ft. lbs or/and 27 ft. lbs?

As I dont know whether the bolts has been changed by the previous owners, How can I tell whether the bolts in the engine are stretch bolts?

Thanks a lot.

Regards,
Danny

[ja17]

 Factory Publication "Technical Data Manual, passenger cars 1966" (page #81), under the 250S, 250SE and 230SL column, lists the torque for "Big end bearing bolts" (connecting rods) should be 6 mkp (apaprox 43 ft/lbs), with foot note #8 reads "With type 230SLwith big end bearing bolts #1210380371 (10mm diameter) the tightening torque is only 3.75 mkp. I believe your connecting rods with the "108" number are the later rods  (43 ft/lbs).

[dnadanny1]

Thanks ja17 for you input again.

Just checking whether my understanding is right, that means 10mm diameter need 3.75 mkp torque, and anything other than 10mm diameter need 43 ft/lbs torque. Is that right?

Thanks again.

Regards,
Danny

[ja17]

Yours with the 15mm nuts and the #108.....   connecting rod, would be the 43 ft/lbs of torque. Early engines using the 14mm bolts and 10mm diameter bolts use the 3.75 mkp (28 ft/lbs). The M130 engine (280SL) used the 15mm nuts also, but they were torqued to 36 ft/lbs plus angle of rotation 90-100 degrees.

[dnadanny1]

Thank you very much.

I will go ahead and torque the connecting rod with 43 lb/ft.

Thanks again.

Regards,
Danny