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MG MGB Technical - Torque Spec for manifold studs/nuts

Does anyone know the recommended torque in ft-lbs for the 5/16" studs fitted with brass nuts used on the intake and exhaust manifolds on the 3-main engine?

Thank you,

Frank Grimaldi
Frank Grimaldi

Hi Frank


You should be safe with 18-20lbs/ft

Peter
P Burgess

My list shows 15ft/lbs.
Richard Coombs

18 to 20 is ok for iron/steel but 15 is safest with brass - any tighter and you risk damage.
C J Carroll

Note that the OE brass nuts, like the exhaust pipe flange nuts, were hi-nuts; standard thickness nuts will not take this much torque, especially when they get hot. Later manifold nuts were a not-obvious form of stainless, also hi-nuts.

FRM
FR Millmore

From experience I feel the nuts will loosen at 15 especially with modern replacement brass nuts over a period of heat cycling. We prefer to use mild steel nuts. In honesty how many of you actually torque these nuts up properly? Most torque wrenches start at 20 lbs ft? The other problem is torque wrench calibration which can be an expensive process or take lots of time with known weights.

Peter

P Burgess

This thread was discussed between 03/10/2011 and 04/10/2011

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