Hardened Valve Caps to fit 3/8" Stem Diameter valves - the standard exhaust valve stem diameter for most SOHC engines. However, this thickness was also commonly used for both inlet and exhaust valves for early OHV and CS1 (Walter Moore type) engines.
These have been CNC machined using original period 'Terry' valve caps as the pattern. These are available in 4 thicknesses - Choose thickness 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:
- 1128_1 : 0089"-0.094" Thickness (approximate 3/32" Depth)
- 1128_2 : 0128"-0.133" Thickness (approximate 1/8" Depth)
- 1128_3 : 0156"-0.161" Thickness (approximate 5/32" Depth)
- 1128_4 : 0181"-0.186" 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 as well? . . . I know JAP speedway engines used to use them). So as of August 2024, we have now made further batch's of both 3/8" valve stem diameter (those shown here) and the smaller 11/32" valve stem diameter - our Item 1127, 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? - but 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 Walter Moore CS1 engines - check your own engine to confirm), which normally use 3/8" valves for both inlet and exhaust - and have 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 is 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! You may also want to consider putting a dab of paint on the sidewall of the valve cap - that is a very easy identifier to remember they are there when stripping the engine!
See also Item 1127 - for 11/32" valve caps (i.e. SOHC inlet Valves) equivelant valve caps
Your basket is empty.
