Custom cams solution
 

So, here is a relatively quick and relatively inexpensive solution to custom cams we have chosen for our SUB set up. We looked into custom length valves to make up the difference of having the oem cams reground with a smaller base circle since the idea of welding up the cam to regrind is less than optimal. About $800 for a set of valves. Not bad, but not a budget solution for sure.

Here is the path we are taking. We are adding lash caps to the lifter bucket stem. The lash cap is really meant for the valve stem, but because of the short tip on the Mazda valves, it would require some customization to work. By inverting the lash caps in the configuration and going to a 7mm diameter, we will be able to put them on the bucket stems with no other modifications. We are going with a .080 (slightly more than 2mm) thick cap. That will allow us to have the oem cams reground and allow us the 10.25mm of lift we want without even clearancing the head for the lobe. Total cost about $300.

There are different thicknesses of lash caps available, so you can choose what you need to make it work for the cam regrind. An additional option is sinking the valves into the head .010-.015 to gain even more. All said and done, it is very feasible to be able to take 2.5mm or maybe even more off the base circle of the cam, which allows for some nice custom options for minimal investment.

Dont the supertech valves come anywhere between 0.6 and 1.1mm longer than stock and need to be ground down for most stock installs?

But for SUB installs they work fine with smaller base circle and generic 6mm lash caps.

If you're looking for more than 1mm additional lift, the supertechs won't do it. That's why we looked into the custom valves. And since the solution is lash caps, there's no reason to spend the money on the supertech valves.

My setup lift 2mm above stock.
The valves can make it as far as I understand it, but it's a dance with springs and spacers to get the rate/pressures you want.

The ST vales are actually really good ones, their best product according to my builder.