Hardened Valve Cap to fit 3/8" Stem Diameter valves. These have been CNC machined using original period 'Terry' valve caps as the pattern. These are available in two thicknesses - state thickness when ordering.
Price is per valve cap
These valve caps are CNC machined to the original 'Terry' valve cap design, they are in case hardened EN32B.
We supply them in two thicknesses - the thickness being the amount they will sit proud of the top of the valve once fitted - the two sizes we offer are:
- 1127_1 : 0130"-0.135" Thickness - this will be sent as default if customer does not make a request when ordering
- 1127_2 : 0185"-0.190" Thickness
The 1127_1 (0.130" thickness) item is one of the thicknesses originally offered by Terry in their Valve Cap boxes (see accompanyning photo of original Terry Valve caps)
Background and Fitment:
First of all - let me say, that I do not normally fit valve caps to my own SOHC engine builds. Not because there is a problem with doing so - but I suppose I have always had the luxery of being able to machine valves to the length I require.
However, I have been asked various times over the years by SOHC engine builders if I can supply them - so, we have now manufactured a small initial batch (as at time of writing this - October 2022), and will make more in the future if popular.
I have heard various stories in the past, as to if Norton themselves supplied valve caps for SOHC engine builds - I have not seen them listed in the main Norton Spare Parts lists cambox sections - but I know they are considered useful if you are building a SOHC engine and cannot get the cambox rocker arms to sit correctly over the valves. They are also useful if you have one valve that is longer than the other, in relation to the cambox, for bringing both valves to a similar height (i.e. fitting a valve cap on the shorter valve only).
And finally, with earlier OHV Norton engines, using 3/8" valves and exposed valves (i.e. earlier non enclosed rocker box) - the same applies, I know of some customers who have engines where the gap between valve and rockers would benefit from valve caps.
In all these instances - it the engine builder's responsibility to decide if they wish to use valve caps - but if they do, these are modelled on the original Terry valve cap design.
Useful tip if fitting valve caps: Remember you have them fitted! .. . i.e. they are normally used on engines with exposed valve tops, and sit on top of the valve, with the rocker pad making direct contact on them - with minimum tappet clearance, which stops them flying off. But they are very easy to forget about and loose when stripping the engine . . . good idea to keep them safe in a bag as soon as you strip engine!
See also Item 1128 - for 11/32" (i.e. SOHC Inlet Valve standard stem diameter) equivelant valve caps