To solve the issue with the adjusting screws, you can install a set of valve stem lash caps. The ones that came on an Isuzu 4-cyl diesel engine work perfectly.

The lash caps restore valve geometry, reducing the extreme angle between the valve stem and rocker lash adjusting screw. It also made it possible to have the adjusting screw locknut in the normal position. Not a lot of threads showing, but of course as the valves wear in, there'll be more.

I got a set of the lash caps from Jerry Lemond, he shipped them out fast and they were less than $30.

Don't have a lot of miles on it yet, but the motor's running very well so far. I left the valves a bit on the loose side for the initial break-in period, so it'll be interesting to see how much they quiet down when readjusted.

BTW, I'm curious what your power band is with the Delta Cam.

My '89 Spacecab 2.6 has tons of low end torqe, but begins to fade past 4000 rpm, and is extremely reluctant to rev past 4500 in a higher gear (such as 3rd gear hiway passing situations).

I recall the old 2.3 in my '86 Trooper (with Delta cam also) being willing to rev to 6K and quite happy too.

But of course these two motors do have different torque characteristics and I've always read the 2.6 is more of a torque motor.

Any thoughts? Maybe the cam timing is a bit advanced; slightly excessive valve lash changing the power curve; or just the stock exhaust strangling the engine???