Rotating exh. Valves

[JimH]

Could someone clue me in as to the advantage (or disadvantage) of converting to rotating exh. valves? I don"t have them now but converting to them will add another $150 to the rebuild tally. I intend to replace the tappets with adjustable types, (much cheaper). I assume the rotating part keeps the seats clean and honed?

 

[Aaron Ford]

Please do not quote me here, but I believe the use of rotators was to prevent hot spots and valve burning. The valve was rotated slightly on each cycle turning a new section of the valve toward the hottest part of the combustion process. I am sure it helped clean the seat and prevent warping, but I cannot say whether or not it is worth 150 bucks. I suppose that would depend on how much use it is going to get. Heck, on my tractor the alternator is optional. It never gets used that much to run the battery dead.

Now for my humble opinion, for $150, you could afford to pull the head and have it reworked.... So unless it is going to be run 24/7, I would put the money elsewhere.

HTH,
Aaron

 

[Dell (WA)]

Jim........yes, rototating exhaust valves tend to PREVENT BURNED exhaust valves and seats and therefore keep the seat seal tighter longer.

Intakes are NOT rotating 'cuz the seats are NEVER exposed to HOT BURNING GASES like exhaust valves.

And NO SEALS on exhaust valves. Why? 'cuz them rubber washers ain't hi-temp proof.
Use SEALS on INTAKE valve stems only to prevent vacuum leaks.

hummmm.......don't believe you can have adjustable tappets without having rotating stem cups.

Iff'n yer changing from split-guide mushroom stem valves (where you grind valve stem ends for tappet clearance, a PITA) to split-keeper straight stem valves and adjustable tappets, ya just gotta byte the parts expense bullet..........Dell