Taking the head back off and checking the valves for proper closure is the next logical step, but
a) the head was rebuilt by a professional machine shop. In all my interactions with him, he was meticulous and noted anything that was even slightly off. Wouldn't he note if the valves weren't closing after he just performed a 3-angle valve job and installed the valves?
b) I'm a particularly meticulous person and a head-off/head-on operation is a complete weekend job for me. I don't really have that kind of time left this fall.

 

Just remove the top cover to check the gear... You can see it if you shine a light in there.
Verify the timing to be perfect.

 

Do a leakdown test. If you have an air compressor, you can do it. Just need a leakdown tester kit. Harbor Freight sells them for 40 bucks. Harbor Freight online is like 30 bucks (plus shipping). That's where I got mine. Works pretty good. THAT will 100% tell you where the leak is IF there is a leak. If the valves never open, you will not draw in any air and hence never compress it. That's why I said if you rebuilt the lifters and didn't fill them with oil then the valves aren't gonna open.

Greddymx5, I give up. You are right, and I am wrong. Lets stop posting in his thread.

 

Yep gues thats what ill do... If you can't handle other input then your own...
You are commenting on my post. Not the other way around.
If there is something wrong with technical analisis on this site, there must be a way for all of us to learn.

 

I definitely do appreciate everyone's thoughts and advice. If I'm a dick right now, it's just because I'm so damn frustrated. I've devoted the last two weekends to this job (and all my spare time in the intervening week); something I thought would be readily buttoned up in a weekend.

Patsmx5, I would have done a leakdown test already if I had a compressor. Unfortunately, the one I borrowed the first time around was from the guys doing renovations on the house next door. I'm going to have to go a bit farther afield for one this time, but when I do find one I'll post results.

greddymx5, I definitely agree that it's worth checking the actual timing belt pulley to verify timing, just don't feel like pulling the accessory drive belts off yet again at the moment.

 

Ok, perhaps your machinist put the cam gears on the cams incorrectly. They will go on 3 different ways I think. Perhaps someone can confirm/deny this. If he put the gears on wrong, that would explain this.

To confirm/deny whether this is the case, align the cam gears and take pics of the cams. With the cam gears lined up and the #1 cylinder at TDC, the two lobes for the intake cam on cylinder #1 should be pointing toward the passengers side. The exhaust lobes for cylinder #1 should be pointing toward the drivers side. If they are not, or if a valve is open (most likely), then the gears were installed wrong.

I can't believe we haven't figured this out yet BTW.

 

I installed the lifters and the cams myself. I did already question the orientation of the cam gears as a possible culprit.

There are only two slots on each gear (meaning each cam gear can go in two different positions). The gears are lined up according to the manual, and the cam lobes are aligned as you describe above. I can get a photo tomorrow.

 

See that? That's for 1.6's too and it's got 3 slots. Thats what my Hanes manual shows too, and I know 94 1.8's have 3 slots, my 99 does, escorts with BPs do, Kia sephias with BP 1.8's have the same gear as well. So I'm guessing you have 3 as well.

Did you have the cam gears off the cam?

 

90-93 Cam gears have only 2 slots.

 

Well, I've had to take another little break from the Miata so, unfortunately, it still is not running.

After having a couple of very knowledgeable people come check it out, the general consensus is that the timing is fine and that the intake valves are not fully closing.

With the cam lobe up, the lifters on the exhaust side still have ~ 1/16" of give left. However, the lifters on the intake side are fully compressed and have no give left. This is consistent across every lifter.

I think that rather than pulling the head again and bringing it back to the machine shop, I'm going to swap to a shim-under-bucket solid lifter setup. I'll order some lifters like these:
TODA Racing USA - Valve Train Kit/Lock Lash Adjuster
then measure the clearances and order some 6mm lash caps (hopefully in the correct height so that no manual grinding is required). I'll probably pick up the caps from Flatlander

Anyone have any advice specific to this plan? Anyone whose done this successfully want to chime in? Here's Y8s thread talking about plans but he never posts after completion:
https://www.miataturbo.net/forum/t16885/

Some other related threads:
Miata Turbo Forum - Home of the turbo Mazda Miata. - View Single Post - Exhaust Manifold survey- 1.6 liter
https://www.miataturbo.net/forum/t15101/
MX-5 Miata Forum - TODA Solid Lifters

It sounds like the oem cams aren't ideal for a solid lifter setup. While I'd love to upgrade cams down the road, that's not an option now. Is running solid lifters on stock cams a non-option?

 

in response to your msg (to my profile, not a pm...?) i haven't taken the lifters out of the box other than to photograph them...

 

Whoops. Meant to PM you, sorry about that.

I guess I should just get those Toda lifters and find out what size shims I'm going to need. I was hoping to find someone that's been through the process and found correct lash caps rather than having to grind them individually like neogenesis2004.

 

Boy it's been a long time.

An update two years hence: the problem was in fact that my machinist didn't grind the intake valves to length. I took the head off, brought it back to his shop, and he fixed it. When I dropped the head back on everything ran perfectly.

Since then, I've moved to California, and now I need to figure out how to get the car smogged and registered. I barely passed emissions in MA so I know I won't out here. Plus I'll need someone really 'friendly' for the visual inspection. Can anyone pm me suggestions for a shop in the Bay Area?