a question about the 5S-FE Head?, Tappets, Valves Options

[RavenAegis45]

I've noticed that the 5S-FE doesnt make use of Rocker Arms like some more modern designs do? does the use of Bucket Tappets have its advantages over Rocker Arms beside Reciprocating mass? Most Modern High-RPM engines like the 2ZZ-GE i've noticed have Rocker arms and use Roller Rocker Followers but thats in conjunction with the VVTL-i isnt it?

And just So Im right the Silver Cylinders under the Cam Lobes are the Bucket tappets right?

[Cuts_the_Pilot]

the only reason manufactures is like you said when in conjunction with a VVTL-I, vtec (boo) mivec etc, because the arm follows all lobes but when they come on lift oil pressure pushes a pin through and then the rocker only followes the high lift cams. SR20 uses rockers too

now all decent engines: 3s, 2jz, 1jz, rb26, 4ag etc all use bucket activation, like you pictured and yes the shiny bucket looking things are buckets

there is 3 different bucket type:

shim over bucket (like gen1 and 2 3s) there is a disk on top of the bucket that you can vary the thickness when adjusting clearances.

shim under bucket (like gen3 3s) you can prob guess, shims are under the bucket, these are superior to over bucket. Shim under allow larger cam lifts without modification, shim overs have been known 2 "flick" the shim out under high speed and lifts.


Shimless buckets (like 1zz) lighter then both shim and bucket method, these use a bucket with varying thickness of the bucket heads themselves, less parts.

Now when comparing bucket actuation to rocker, bucket has less moving parts, is lighter, less complicated but noisier.
Rockers are well the opposite. more to upgrade for high lift/duration cams, have been known 2 float around but are quieter, especially in hydraulic lifter applications.

[RavenAegis45]

I see, thats very insightful, thank you