Hey guys, looking for a bit of help

My 1990 1.6 head was built Supertec valve, double hive springs and titantim retainers from 949, OEM Mazda valve guides, and Felpro valve seals, and assembled using an OEM Mazda head gasket and ARP head studs, and new lifters.

After assembly, the engine ran great on the dyno while being tuned.

At the track the car started to show signs of issues during my second session. I pulled off and ran a compression test (120, 120, 90, 60).

Put the car on the dyno at the track to check AFRs and power. First two runs were perfect, on the third run I fully dropped #4.

Ran another compression test and #4 was at 0.

Took the head off, head gasket was perfect and cylinders/pistons looked great with no sign of blown head gasket.

had the machine shop check the head and everything looked perfect.

Re-assembled everything, same issue, #4 at 0 compression.

With the intake and exhaust manifolds NOT installed, I ensured the valves were opening and closing.

Performed a leak-down and air was pouring out of the intake manifold side of the head. (Intake and exhaust manifolds still removed)

Performed another leak down test with the cams removed, and head held air.

Performed another leak down test with the cams from a spare head, and air was pouring out of the intake manifold side of the head.

i also tried the original lifters with the same result

Needless to say I’m petty frustrated and any help would be appreciated

 

Sorry to say this but you are another victim of shitty Supertech Valves.

Your intake valves now look like this

 

Inconel for the win.

And find a new shop. No excuse for rebuilding and not leak testing.

 

Yes, like the cats above said, the ST intake valves can be junk. They’re known to stretch/elongate and either drop seat pressure or in your case, reach negative lash and stick open.

+1 for dropping that shop over not checking for leaks

 

I just had 4 Supertech valves go bad on my motor. Built 20,000 miles, ago, wouldn't seal anymore.

If u ever had to do it again I'd tell my shop to use custom ferrea valves, - _-

 

Plus 1 for Ferrea valves!

 

Does anyone have the spec sheet to order custom valves? Could probably order a new ST valve and just send it to them I would assume.

 

https://www.ferrea.com/custom_valves.php

Unsure if there are quantity breaks, but you could investigate a group order for disgruntled ST users.

 

I found that but dont know the numbers to put into the blanks.

 

Headgames Motorworks deals with getting Ferrea custom valves all the time. They quoted me at about $40 each which is more than the ST. But they aren't having problems and have used them for years. They are being run on 20 heads that are competing in the TX2K this year.

It seems pretty flexible, but maybe going through a shop with established relationship with Ferrea wouldn't hurt for group buys.


They already had two sets of my valves in hand.

 

Yeah, I'm similarly lost aside from stem diameter, head diameter and overall length. TNTTUBA may be able to help

 

Wow, I’m ******* furious. Has anyone had any luck getting them warrantied/refund/etc?

 

I don't believe so. I think TNTUBA was able to get further with ST than most and I believe he received a replacement set that supposedly had some fancy stellite treatment on the stems, but they did the same thing. Its documented well enough that you could approach them about it, but you'll likely get told to go pound sand.

 

I no longer use Supertech Products nor will I ever again nor will I ever recommend them.

I was able to get a set of Supertech Valves to last buy running over 100psi of seat pressure (I run crazy cams....but I still think it takes more than their heavy doubles make out of the box to get them to last.) but was frustrated by the QC issues, the lack of transparency from the leadership and even when confronted face to face at PRI being told the issue was related to ANYTHING but Supertech only to find out later they actually HAD changed their manufacturing process.

If you want something off the self that will alst and not break the bank. I have had good luck with the Manley SS Intake valves. I am running a set of one off exhaust valves.

 

Recently Emilio edited his Engine Building Ideas thread so it no longer has the huge amount of information on it but up until then ST was recommended on that thread with lots of appreciation from people.
In that original writing it stated that depending on combustion temperature you should plump for a material not a manufacturer. (<1650 OEM, >1650 but <1750 Stainless, >1750 but <1900 Inconel).
It also stated about valve springs needed being from ST which through inference would point to ST valves too.

So if ST valve have such QC issues already known, so many people here run them, is there another brand used by others for off the shelf?
Custom is great and all but surely someone cares about our little cars?

 

It seems as though TNTUBA has had good luck with Manley.

 

Yes I did see that but TNTUBA is running a NASCAR boxed supercharged 2G pulling mental exhaustion car so I figured there might be another alternative too
I've also had a look through the master catalogue and not found the BP engine mentioned although once again custom measurements can be taken.

 

I just typed in "Manley valves miata" in Google and this came up

http://www.manleyperformance.com/sc/...p_valves.shtml


https://5xracing.com/i-23993341-manl...-8l-miata.html

 

Forum formatting quirk. I added some info about billet cranks and the site clipped the post in half. New character limit. Had to contact moderator to manually embed the edited text.
Took a while to fix. Correct now.

If it ever kills the OP again, the info is on our site: https://supermiata.com/tech-info-links.aspx

 

We pulled Supertech's valves off our site a few months ago. Twibs just had the same thing happen with their new stelllite valves. I have a set of Manley SS intake valves in a customer's head as well, I'll know more in a year or so when it has enough hours to know whether or not they are better.

Having said that, I doubt strongly that their valves are your only issue. It is possible to do this to any valve (even OEM) if your incompetent machine shop tried to get cutesy with the seat widths (see below re: your machine shop...), or if you are running too much RPM and not enough spring pressure for your specific setup. I trashed a set of OEM intake valves last fall in Rover running 7300rpm with HLA lifters and Supertech single springs. With everything else factored in, it always took several events and at least 10+hrs of runtime for this valve problem to show itself when I've seen it in the past. If you had it crop up after dyno time and 2 sessions on track, there was more going on than just bad valves.

Fire your machine shop, BTW. You sent them a head with tuliped valves and they didn't catch it. That is CC chargeback levels of incompetence IMO.