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Rocker Arm Eccentric Bolt Question


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There's a great torque tightening reference page for the M10 motor on this forum.

 

Im looking at it right now, I just want to verify, the tightening torque for the rocker arm eccentric bolt is only 6.5 - 8lb ft, according to the chart linked below. Seems low, just double checking before valve adjustment.

 

 

Screenshot 2023-01-15 at 1.58.26 PM.png

'72 Metallic Malaga 2002 with a '73 M10 | Dual Weber DCOE 40s | E21 5spd and LSD | Pertronix II

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45 minutes ago, tzei said:

I think i go harder. Specially steel rockers seems to need more.

 

^agree^

 

I've had some KM steel rockers which required torque of 'just-about-stripping' to hold the eccentrics.

 

The torque required for Lester Owens steel rocker arms is more reasonable/comfortable (Lester's being a better piece, in my opinion).

 

And, IE's heavy duty rocker arms usually require more torque than OEM-spec (especially if you use IE's eccentrics, which I've found are sometimes a couple-thousandths thinner than OEM eccentrics). -KB

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My primitive--but effective--method (never had one loosen) is to use a 1/4" drive ratchet and tighten the 10mm nut until the edge of my index finger (pressed against the ratchet handle) hurts a little bit.   That's for the OEM aluminum rocker arms...

 

mike

'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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Yeah, agreed- tighter than it really ought to have to be is about tight enough!

 

I've always got a spare nut or 2 kicking around (shut up, Esty)

because the first thing to go is the thread on the nut.

And it's an odd (fine) thread.

 

t

 

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"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Alright! Just finished this up, motor is a bit quieter. Occasional chatter. Video sound OK to you guys?

 

I realized I wouldn't have been able to torque all the eccentric bolts anyways because my sockets are too thick with the torque wrench. Made them pretty snug, I guess we'll find out if they are OK or not lol. 

 

 

Edited by 72MetallicMalaga

'72 Metallic Malaga 2002 with a '73 M10 | Dual Weber DCOE 40s | E21 5spd and LSD | Pertronix II

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On 1/16/2023 at 8:03 PM, 72MetallicMalaga said:

Alright! Just finished this up, motor is a bit quieter. Occasional chatter. Video sound OK to you guys?

 

I realized I wouldn't have been able to torque all the eccentric bolts anyways because my sockets are too thick with the torque wrench. Made them pretty snug, I guess we'll find out if they are OK or not lol. 

 

Kinda hard to hear valvetrain noise, I think I could more hear the dancing intake screens :) Maybe try a video from the exhaust side, closer to the valve cover.

 

As for torque specs, unless you have a really good and well-calibrated inch-lb torque wrench (Snap-On or the like), one shouldn't become too reliant on that with such low torque specs. Practice and feel go a long way. I have seen plenty of amateurs and "professionals" either greatly under- or over-torque fasteners while using a torque wrench. 

 

It is impossible to get a torque wrench on the valve adjuster locknuts of most of the cars I work on (air-cooled Porsches and old BMWs) so learning by feel is a must. Don't get me wrong, I am all about using a good torque wrench any time it is practical and possible!

 

A great exercise is to use scrap pieces of metal and/or old parts that already have tapped holes, set up some bolts and nuts with washers, and look up average torque specs for the grade/size/pitch of the fasteners you have. First tighten and torque the bolts/nuts by hand, then go back and use a well-calibrated torque wrench and see how far off you were. Rinse and repeat until you have a good feel for what it takes to tighten and loosen the bolts.

 

This all goes out the window a bit when one gets to torque-to-yield or "stretch" bolts used in modern cars which have a torque-angle spec and are designed to only be used once. Anyone here who has experience with the myriad aluminum stretch bolts used on BMW's mag-case N51/N52 series engines knows the sickening feeling of the bolt stretching as you apply the final 90 degrees of torque---instinct tells you to stop, but it is normal for that application!

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Chris A
---'73 2002tii Chamonix w/ flares, sunroof, 15x7s, LSD, Bilstein Sports w/ H&R springs, upgraded sway bars, E21 Recaros
---'86 Porsche 944 Turbo grey street/track car

---'81 Alfa Romeo GTV6 rescued from junkyard, Lemons Rally/"GT" car

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