351M rocker arms
 

Are the 351M and 351C rocker arms the same? I just installed a Comp Xtreame Energy XE274H-10 cam in my 79 351M. I was wondering if I could put 351C roller rockers on it?

Yes. You want 1.73 ratio.

The rockers are the same, but check the fulcrums. The Clevelands had aluminum fulcrums, the late 351M's had iron fulcrums. The iron are what you want. They can also be sourced out of a 370/429 truck engine.

the roller rockers will be the same and are all the same ratio. If you don't put in studs for adjustments you could have problems with geometry.

Rockers
 

Thanks for the info.. Will the 1.73 give more lift on the cam? adv dur is 274 286 with .562 .565 lift

No, that's the stock ratio for all the Cleveland/Modifieds

.. Yes, that cam already shows good lifts... that same cam in a SBChevy with stock 1.5 rocker arms would spec. out at much lower lifts...

.. As BearTracks hinted at, rocker fulcrum shims may be needed or changed to get proper hydraulic lifter preload...

.. If you're not satisfied with the performance of your 351M with that cam, it's prolly because the compression ratio is too low and that's difficult to fix with available off-the-shelf 351M pistons, hence why everyone converts 351M's to 400's...