Can I use '99 exhaust cam for '94 exhintake?
 

I swear I saw a reference that mentioned that it was ok to use a solid lifter cam on an hla head, but not vice versa. I picked up a cam out of a '99, but now can't find the original reference that read. Can I use '99 exhaust cam for '94 exhintake?

I thought you couln'd mix and match, any way...

Someone can say the opposite ?!?

Precisely why I'm asking the question :) . I thought I saw that it has been done successfully, but can't find where I saw it. This is one of those mysteries it appears, such as the 'can I turbo a skyactiv' curiousities.

Seems to me that I had read the same thing on here but, like you, I can't find it. Really would like to know for future reference, anybody?

A cam for solid lifters have a ramp for picking up the lash before it transfer over to the valve acceleration "flank" ("ramp" or other word you like to use).
A cam for HLA does not need this ramp so it starts with the valve acceleration directly.

It's makes a bigger difference when closing the valve (let it down easy or drop it brutally).

Remember that you cannot have zero lash when using a solid lifter, so the HLA cam will bang the valves pretty hard against the valve seat.

How much you will "lose" with the lash ramps on a HLA (since it will slowly open the valve early and slowly close it late) I have no idea, but it will not have the brutality on seats of switching the other way around.

Optimal? No.
Will it kill you? Probably not.

Found some old references today on miata.net. Without doing further research, a few posts back from 2005 indicate gap/clearance incompatibility, which is reason enough to avoid using the NB solid lifter cam on the NA HLA head.

NB cams in an NA... - MX-5 Miata Forum
"Either the base circle, or the valve-stem length is different between NA and NB, so the lifters take up a significantly different sized gap.... in the order of 2mm (0.080") which is far more than you can expect the HLA's to expand... "

"There is a difference in the valve stem length, but it can be made up for using OEM shims. It'll all work fine if you keep the lifters and cams together (solid with solid, HLA with HLA). Mazda was even kind enough to keep the CAS drive, so that all works fine."

M.net FUD

The base circle is the same on all BP cams (BP4W, BP6D).

If you want some reading on the cam specs (ehm, measurements to judge Tech Shed legal).
https://nasa-assets.s3.amazonaws.com...v6.pdf#page=21
Yes, the 1.6 cams are different ;)

You could always do yourself a favor and grab the proper cam out of a junkyard Kia Sephia.

It'll probably cost $25 at the most. $30 if you carry it up to the cashier with the cam gear still attached.