This is the arm fitted to exhaust lifter mechanism on OHV engines, and comes with the special 'reduced head' nut fitted to these arms to avoid fouling rocker boxes. Both in stainless steel.
If you already have a fully running motorcycle, then chances arm you do not need this part, as they rarely break - but if you are building a new engine or have a restoration project - the exhaust lifter arm assembly is very often missing and now very difficult to find.
This exhaust lifter arm is taken from the same (malleable stainless steel) casting as we use for the SOHC exhaust lifter arm and gearbox clutch arm. However, for this arm, the slot and thread is on the opposite side - as per the original OHV exhaust arm, so the bolt head is accessable with a spanner without fouling the rocker box. The other main difference with this arm is that it has a more acute bend than the SOHC arm, to reach the OHV cable adjuster - we do this by heating the casting to cherry red, to allow the arm to be repositioned without damage and then allowed to cool slowly to avoid stresses. The arms themselves are CNC machined, as are the special nuts, and have the correct recess for the cable abutment as originals did
It should be noted that the original OHV Exhaust Lifter casting is slightly different to this arm, and the original arm is fractionally longer. Due to the small amount of demand we have for this arm - we could not warrant manufacturing a new pattern, so the SOHC has been modified to do the job - so we can offer a usable alternative. However, other than the arm reach being fractionally shorter, it does the job just as the original.
The bolt that comes with the arm is modelled on the original, with correct chamfer and reduced head shape - again, so a smaller spanner can be used without fouling the rocker box. This is CNC manufactured in stainless steel
This arm will fit both types of OHV engine shown in the photograph - on the left is a 1938 - 47 rockerbox and on the right is a 1948 - 59 rockerbox. It may also fit earlier OHV engines - but I have not tried this, so email us for details if you have one of these earlier engines
Note - in the 4th photograph we show a picture of the correct Norton type Volute spring used with these exhaust lifter arms - we sell this item seperately: Item 0379.
In the final photograph you will see the 1948-59 type rockerbox on the right has the exhaust valve spindle removed with the exhaust lifter arm fitted to it. This is actually a new-oldstock item I have as a pattern. I do not have any plans to make this item at the moment but email on firstname.lastname@example.org if you require on and I may consider making a batch