ET: Engine (Twin) Rocker Bearing shims

bmetcalf

Well Known and Active Forum User
VOC Member
VOCSC list ET243 Rocker Bearing shims. My front head rockers both shift back and forth, so I assume the hole in the top is worn oval. I intended to replace both so that the rocker feed bolt would hold them in place. All three variants of rocker bearing on the VOCSC website are noted as "Oil feed oil is sized to fit the modified ET100/1 feed bolt", which is enlarged to 3/8", which may force me to locking bolts. Maybe not the worst thing to do or would the shims take care of the shifting satisfactorily?

Any thoughts/advice?
 
Last edited:

Bill Thomas

Well Known and Active Forum User
VOC Member
Bruce if you fit locking feed bolts, You may have to grind a bit off the top of the rocker arms,
If you look at the photo of the rocker arm in VOC spares,
You can see what they do now.
Cheers Bill.
 

Attachments

  • 1382_ROCKER_ARM_-_MODIFIED_thumb.jpg
    1382_ROCKER_ARM_-_MODIFIED_thumb.jpg
    2 KB · Views: 22
Last edited:

stu spalding

Well Known and Active Forum User
VOC Member
Hi Bruce, the Spares Co rockers have way too much metal removed. In the pic below an "expert" took far too much off the fore rocker, the rear has had all that is needed removed for clearance. Cheers, Stu.
 

Attachments

  • 5   Rockers.JPG
    5 Rockers.JPG
    306.1 KB · Views: 42

Ian Savage

VOC Vice President
VOC Member
ET243 Rocker Bearing shims are for side play and are a Vincent part listed in the later D parts book.
I have fitted locking feed bolts in all my heads since the 70's amiterishly grinding off the tops of the rockers with no failures.
The machined rockers the VOCSC now stock have been supplied for a few years without issue. Being as the metal is in compression in that area there is plenty of material remaining, having seen original factory lightened rockers probably 25% of the metal removed.
The machined area is also smooth not with the sharp stress raising points as in the second photo.
 

stu spalding

Well Known and Active Forum User
VOC Member
Hi Ian, I'm merely pointing out that in my pic, enough metal has been removed to allow for an inch and a quarter of valve travel, which is ridiculous. Cheers, Stu.
 

Bill Thomas

Well Known and Active Forum User
VOC Member
I made my own in the 70s and don't remember needing any metal to be removed,
And that was with Mk2 cams, But I think I made mine slightly different.
Cheers Bill.
 

vibrac

Well Known and Active Forum User
VOC Member
I think ET100 originals are no longer stocked now that is an acclamation for a riders mod from the dark ages what a good idea it was.
 

Bobv07662

Well Known and Active Forum User
VOC Member
Bruce, I agree with the above posts that the service rockers have way too much material removed to make room for the locking bolts and t-nuts. A little material removed goes a long way.
Knowing that the rocker bushes are solidly located rather than "shimmed" is the way to go.
 
Top