Hardened Valve Caps to fit 11/32" Stem Diameter valves - the standard Inlet valve stem diameter for most SOHC engines. These have been CNC machined using original period 'Terry' valve caps as the pattern.
These are available in 4 thicknesses - Choose thickness required from Dropdown list when ordering - once selected, each thickness will show as a 'Green' bar, or a 'Red' bar if out of stock.
Price is per valve cap
These valve caps are CNC machined to the original 'Terry' valve cap design, they are CNC manufactured in EN32B before case hardening.
We supply them in 4 thicknesses - the thickness being the amount they will sit proud of the top of the valve once fitted - the 4 sizes we offer are as follows:
- 1127_1 : 0089"-0.094" Thickness (approximate 3/32" Depth)
- 1127_2 : 0128"-0.133" Thickness (approximate 1/8" Depth)
- 1127_3 : 0156"-0.161" Thickness (approximate 5/32" Depth)
- 1127_4 : 0184"-0.189" Thickness (approximate 3/16" Depth)
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, as of 2021 we introduced them in two thicknesses - they sold out almost immediately - so clearly a lot of Norton engine builders seem to be using them! (or maybed other marques? . . . I know JAP speedway engines used to use them). So as of August 2024, we have now made further batch's of both 11/32" valve stem diameter (those shown here) and the larger 3/8" valve stem diameter - our Item 1128, now both in the four (4) depths shown here.
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 (or earlier Walter Moore CS1 - check your engine), using 3/8" valves for both inlet and exhaust 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. For 3/8" valve caps - see Item 1128
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! Another usefule tip is to paint the sidewals of the valve cap - that helps remind you when stripping the engine!
See also Item 1128 - for 3/8" (i.e. SOHC Exhaust Valve and most Walter Moore CS1 and all Norton OHV standard stem diameter) equivelant valve caps
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