I have a 51 Mercury. I just rebuilt the engine and installed an Isky Max 1 cam. I searched all over for valve lash specs, and the only ones that I could find are .018" and .014" cold. The valves seem to clatter a lot when hot. What do you other flathead owners set your valve lash to?
The 49-51 Mercury Manual says that the 51 Merc valves are set as follows: Intake .013 to .015 Exhaust .017 to .019 The 49 and 50 Merc valves are set .010 to .012 for intake and .014 to .016 for exhaust. All settings are cold.
I guess I am puzzled why you would ask people you don't know rather use what the manufacturer (Isky) said to use (0.014 int; 0.014 ex). Farmalldan
Non-OEM spec cam means Non-OEM specs. The 51 was the first year for rotator valves in the engine but the early 51s are just like the 49/50 since the rotators weren't phased in right away in late 1950. Rotators valves use the late OEM specs with the OEM cam & earlier non-rotators use early OEM specs with OEM cam.
You should not deviate from cam manufacturers specs more than a few thousands because it affects the cam follower (lifter) initial contact area with the ramp of the cam profile, which affects a wear pattern. Call Isky, you can surely get the specs from them.
should a flathead sound chatty? mine sounds a little loud, like a quiet diesel engine. old timers around here say its normal. I have read on the ford barn a flathead should be quiet, so quiet all you can hear is the fan running, so I redid my valve lash, made it .012 intake and .014 exhaust, made no difference in sound.
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