Just got my head(750 Combat) back from RGM which included new guides, valves and seats re-cut
When I reassembled the springs and collets I have noticed the exhaust rockers line up with the valve stems centrally but are slightly towards the rear (just slightly off) the stem
Lawrence at RGM removed the rockers to do the work and I was wondering if he had reassembled them in a different order or doesn;t it matter or is this normal
Inlet are fine (central and more or less in the middle of the valve stems)
Ken
commando rockers
Ok leaving RGM out of the equation, Is it normal for the tappet adjusters to be slightly to the rear of the valve stems. I know when the valves are depressed the tappet adjusters will align centrally with the valve stems but its the initial contact I was looking at
- Log in to post comments
Rocker photo
Here is a shot of my 750 Combat head - all original & under 15 k miles - they do indeed appear to be a bit eccentric in the fore & aft axis but I believe they become more centralized as the rocker swings through it's arc and the stem moves downward . This must impart a slight sweeping motion on the stem itself .
- Log in to post comments
Contact point
If the contact point of the rocker is aft of the stem and centralises as your cam rotates the rocker it would suggest the valve stem is fractionally too long.
If its the reverse and your contact point moves even further aft then its too short. The rocker is a rotating part; we utilise a few degrees of that rotation and translate into straight line movement of the valve therefore there is an element of "sweeping" over the top of the stem.
The higher the lift of the cam the more "sweep" involved. New components, new machined seats all have an influence on your valve geometry.
The "ideal" static check is for the contact point of the rocker to sit central to the valve stem when the valve is lifted 50% of its travel (then your sweep would be centralised over the stem head).
But believe me the majority are not...
Cheers
Jon
- Log in to post comments
Maybe you should speak to RGM first before putting this on the forum Ken