Miata Turbo Forum - Boost cars, acquire cats. - VVT RPM limits and questions

- Engine Performance (https://www.miataturbo.net/engine-performance-56/)

- - VVT RPM limits and questions (https://www.miataturbo.net/engine-performance-56/vvt-rpm-limits-questions-95139/)

I ( with a gleam in my eye ) decided that I would change my 99 Miata and add a VVT head. While I haven't yet gotten to fire up the car yet and hopefully grin with a more robust push of torque in my butt ( no comments needed about that thank you! ) I encountered something that I want to run by the VVT guru's and experts and well anyone who has dealt with one. I purchased the Seal kit and dismantled, cleaned and put the sucker back together. Upon installing it on the engine I noticed a small amount of gear play which I suspect is the clearance between the locking hole and the spring loaded pin in the VVT. Has anyone else noticed a small amount of movement and is this considered normal? I'm not talking about an 1/8 of an inch here, maybe the tooth on the timing gear moves 0.015-.0.020"? This is without the belt installed of course, just sitting there free and exposed.

Thanks.

It is the play between the cam dowel and the gear itself which leaves when the cam gear bolt is tightened. :doh:

Quote:

Originally Posted by TNTUBA (Post 1467492)

One thing you need to remember when setting your valve stem height and spring pressure is that the Over Sized ST valves are .6mm longer and that length is under the keeper. That effectively reduces your seat pressure by roughly 8 lbs with the ST doubles.

I didn't build my head... Is this something a competent builder should have caught and accommodated for?

Quote:

Originally Posted by TNTUBA (Post 1467492)

You sure about that? I recall it being above the keeper so the builder could “tip” the valves to adjust for proper shim ranges.

Dial calipers don't lie. They aren't built long to allow for tiping the valves, They are built longer for guys running smaller base circle cams.