Supertech stock length valves don't mention back cut or undercut in stock diameters for our cars. The valves in a stock diameter mentioning back and undercut are longer. Intake is 1.1 and exhaust is .6 longer than stock. I know on the 99 heads you could use thinner shims, what about with earlier HLA's? Are these for use with cut down cams? Plug and play or would these take additional machining?

 

My shop machined them down to correct lift/play/clearance/whateverz I pay them for.

 

I am not sure how to answer that, but if I have any valvetrain issues, I call either Mazdaspeed Motorsports or Webcam. Mazdaspeed techs are very helpful, and will tell you what your options are. Another option is to contact Integral Cam. I personally have not talked to them, but have heard from others that they are helpful.

 

Sent the question off to Belfab/supertech. Seems odd the only valves they have mentioning back cut are longer ones.

 

Only the "standard flow" ones don't have a backcut because they are for stock class racing. As for length, I posted the results of my phone call to them. Search for my thread.

 

I have interest in this, too. I looked for your build thread, but didn't find it in the usual location. Can you help us out?

 

Dude, search by my username, keyword "supertech":
https://www.miataturbo.net/forum/t41...ight=supertech

 

Supertech/Belfab returned my email inquiry. They said they are designed to work with Supertech springs. They are longer than stock springs to increase lift for FI and support higher revs. Stock cams and head are supposed to work fine with them.

 

nice!!!