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when [ year or serial # ] did the L134 engine change over to the rotator-type exhaust valves ?....thanks for any help ...Kent

Huh? The L134 has always had the exhaust valves in the block pushed via the cam. Maybe I don't understand your question.

trying to find out when the L134 engine went to rotator type EX. valves...older engines did not rotate EX. valves...read the question again ...thanks Kent

I read it the 1st time, not much there to read to miss anything. Anyway, I guess I have no clue what you are talking about.

Hi Bretto,
He is talking about the part between the valve spring and the valve adjuster on exhaust valve. F-heads are using them too.

most modern engines have a rotator on the EX. valves to turn them slightly on the seat every time they open so that if a piece of carbon gets on the valve or seat it will move instead of burning ....without rotator valve opens & closes in the same place & will burn more easy...older L134 engines did not have this feature....my M38 manual TM 9-1804A indicates that the M38 series 4 engine came with rotators...2 out of 5 of my parts engines have them 3 don't...just trying to find out when they started installing them ...all F head engines [M38A1] were equiped with them....thanks

Read up on it. New to me thanks.
56. Rotator-Type Exhaust Valve
(fig. 61)
The rotator type exhaust valve used on this vehicle consists of a
special valve spring retainer, valve cap, two retainer locks, a spring
seat, and a special hard faced valve. A standard valve spring is used.
57. Operation of Rotator-Type Exhaust Valves
At the beginning of the valve lift, the valve tappet first pushes the
valve cap (fig. 61) through the nominal clearance, taking the spring
load off the valve before it opens. This action results in the valve
being free once it starts to open and remaining free until it close’s,
permitting the possibility of slight valve rotation during each cycle.

I believe all the M38 L134's came with rotator type exhaust valves. Both the early 1951 ORD 9 and later 55 ORD 9 show the same valves and the M38 engine manual dated June 51 shows the rotator type only.

I also know the civvy CJ manual SM1002 Rev 5 dated 1965 says the L134 was never produced with rotator exhaust valves but I believe that is an editing error as the manul was revised it overlooked the rotator introduction around 1949.

thanks for the info