I almost suggested you 3d print some of the top latch caps to try and tighten up the fit, but I suppose the new latches would've come with those.

Nice attention to detail and design on all the parts.

 

I have those RUCA-O adjusters, Mania sold (sell?) the modified arms here. Your design looks a whole lot nicer though, please post photo of finished article.

 

I've replaced the top caps before, and the ones on there were okay (cracked, but present), I've tried adjusting the strikers on the windshield, I've adjusted where the top latches bolt to the top, and tightened the latches, I've replaced and adjusted the frank bolt plates... I'm not sure what I can do that I haven't tried to get a tighter fit. I'm going to take a pair of the old latches apart some day and see if I can't get them to pull tighter. Plus, anything I learn can be transferred over to the hardtop rear latches that are much less common. The top set I had installed actually was loose enough to let daylight through at the corner if I looked juuust in the right spot. This new set is so much nicer.

I definitely will post pictures of the progress on all these little doodads. My CNC buddy is hounding me to send him work, he must be bored!

Here's another project I've ignored for too long. I bought almost two years ago and I'm tired of it haunting my house. Here's the idea that I shared back in September 2024. It's reasonable looking cosmetic spoiler at first glance, but with a piece of plexiglass it can become something that's wind tunnel tested to create substantial downforce, without a wing.



I found that McMaster Carr sells these fasteners that are intended to be bonded to a panel. They're called Rotalocs.



But how to get them into place on a hollow spoiler, where I can't reach them directly?

Well, first I made the holes they would be mounted behind. I used a 3d printed L bracket to mark and align the holes based on the edge of the spoiler. Since fiberglass will tear and break, I used an abrasive grindstone attachment on my die grinder. I didn't take any pictures of that, it was done a long time ago before I lost momentum.

Then, I designed a one time use tool to thread into the Rotaloc. I grabbed the 3d file for an M6x1 bolt off McMaster, then added this head that would center the Rotaloc in the hole I had previously created as well as give me a place to hook to it.



I used the world's greatest named adhesive, and again, the 3d printer came to the rescue since I had lost the dual piston plunger tool meant to dispense the epoxy.



The Rotaloc got a healthy coating of DP420, and I used my fishing rod to (sigh) fish it through and pull it into place at each bolt hole.



Here's the center attachment point gooped into place, viewed from the access hole I created.



Removing all the plastic pieces went well, it took me about 30 minutes. I did a lot of experimentation on the first one, trying various tools to risk the least amount of damage to everything. It took 20 minutes on its own. The last one took about a minute and a half.

So now I have clean threads, evenly spaced and almost perfectly centered in the holes



And I a 3d printed a support for the replacement third brake light.



I'm going to get a quote on having this painted Silver to match the rest of the car. I really have to resist the urge to just paint it satin black, but that'll be dictated by how many hundreds of dollars they want for a quick spray.

 

I love this spoiler side project. I've always pondered why there wasn't something more attractive than the usual lexan BBFW style, and considered making something of my own based off the aluminum bolt on style you can find on eBay with a bolt on extension. Excited to see what you come up with!

Side note, DP420 is a great name for an adhesive and is meme worthy of itself.

 

I'd been hoping to get to VIR this weekend with NASA, but things just haven't gone my way. All things considered, it's not the worst thing.

I aligned the car the other day at a friends house, as my garage has a super uneven floor. That went well, but was another reminder that I want that RUCA-O eccentric adjuster. The back and forth between camber, toe, and the finished thrust angle check is an annoyance.

The car has developed some kind of resonating rattle from the underbody, seemingly from the cat on my Flyin' Miata midpipe. It has this distinct tinny sound like an old air cooled VW. I've pulled the cat off and found no damaged cells that I can see, and it doesn't rattle off the car no matter how hard I knock it. Once it's back installed, the rattle comes right back. It's super obvious to anyone near the car. Not cool.

I pulled out my race seat to install it when I realized the clip in portions of my 6 point harness are AWOL after my moves this year. The extra belts I have are 3" and won't work with my QRT-R seat. The webbing was expired anyways, so I'm ordering another just like it (Crow Enterprizes Enduro) and hoping that the missing pieces show back up. If they do, I'll get it rewebbed for a passenger seat. I've had friends ask for ride alongs, and if I am serious about being an instructor it would be good to be able to bring people along.

Anyways, my new target is to get on track next weekend. Porsche Club is having an open track event after their shenanigans. It should be 2-3 hours of open track access. Maybe I can even have the spoiler painted and installed by then!

 

Dang, those little Rotaloc things are sweet! Great job with the spoiler so far, can't wait to see it done.

 

I've registered for a Porsche Club weekend close out open track session this Sunday. It's currently scheduled to have 3 hours of open track at VIR on Sunday evening for the princely sum of $300. That's the sort of value I'm interested in! I ran a similar event in 2024.

The only downside is... well, Porsche snobbery. They want an approved "Marque Specific" race shop to do a very cursory inspection. I might be less flippant about it if they asked for a single bolt torque check. Asking for a race or brand specific shop to put my car on a hoist for a visual inspection is like requiring asking that an elementary school physical be performed by a surgeon. It's just pointless overkill.



The last time I went, I visited a reputable and local Spec Miata shop to get his signature. He just asked me some questions, glanced at the general condition of the car, and signed off on all of it. Nothing on this inspection can't be done with the car on the ground, or any tool more expensive than a mirror if you're going to look at ball joint boots. I think this time I'm tempted to just go to the corner shop near work and have them give it the same treatment. After all, that's about the same level of care they put in to my state inspection.

Anyways.



I can't believe how good this $100.35 Maaco paint job turned out. It's a fantastic color match, and while there are a few pieces of dust that have made for imperfections, it's really well done all things considered. I'm bringing my Jeep back to this place for sure and I wish I had just gotten my hardtop painted here. The people working there actually cared about their product and made jokes about the expectations at a Maaco! There's a few spots where some filler would have made for a nicer finish, but I decided against doing that myself. I figured I'd be more upset about Bondo cracking or separating than I would be about uneven reflections at the edge of the part.

Part of the delay in getting this project done was how much I like the NB's butt. The lines are clean and curvy. I was afraid the spoiler would ruin it, but I don't think it does at all.



This is just a test fit, it's only resting in place. I'm going to take it into work tomorrow to bake it in the large paint oven we have for a final cure before final install. I plan on just using some VHB tape to secure it. Any impact will probably rip the thin fiberglass in two before it rips it off the trunk.

I also got in the new Crow Enduro harness and installed it. Here's to another few years of tracking!



All that's left to do before the track day is a quick brake bleed, torque check, wheel swap, and oil change to the usual Brotella T6 now that the engine is broken in.

And to pack my GoPro for once.

 

Pack your GoPro now, I wanna hear and see that baby singing on track again.

And the spoiler came out sick! Looks great and compliments the rest of the car nicely.

Your guys’ POC doesn’t make you guys buy a yearly membership to run their events? I remember they held an autocross near my place a couple years back, but required a $150 or something yearly membership to sign up. I think it was in October or November and when I messaged them asking why they didn’t offer a single day license they responded with: “Yeah but you can sign up for our other events for the rest of the year!”

 

Sexy spoiler!! Looking good dude. Also the Porsche snobbery gave me a good laugh, I've never heard of a track event requiring that kind of inspection.

 

When I went to bond on the spoiler, I noticed the packaging for the "VHB" was obviously cheap knock off quality and found discussions online said pretty much all of it bought off of amazon was counterfeit. Don't know why I didn't notice that when it was a recent purchase... Anyways, I went to O'Reillys to get some genuine 3M Mounting Tape. It's probably just some variation of VHB, of which there are many. There's a few spots that are a bit stressed towards the edges and didn't bond as well, but it should be stuck on there for good. To bond it on I applied the tape to the spoiler with a bit of excess backing tape hanging off the side. With the spoiler positioned and another set of hands there to help, we pulled that excess backing tape off, peeling it while the spoiler was pressed in place. I can't imagine how difficult it would be to do a one take install with a push and stick, where I just hoped I got it right the first time.




Since the stock 3rd brake light is covered, I added a cheap and small LED brake light meant for a 2005-2017 CRF450. It's just a 3d printed bracket first shown months ago bonded with knock off 3M VHB. I ran the wires through one of my busted license plate lights that was already held in place with tape.

It doesn't show in pictures, but multiple people have told me this new 3rd brake light is brighter than the other two brake lights when seen in person. Sounds safe to me!


I got the oil changed to Brotella T6, gave the car a once over torque check, and headed to the track.

The Good:

I sailed through inspection, Porsche people are pretty chill, the car handled great, and I had an amazing time on track. Towards the end I basically had VIR to myself and there were several laps where I never saw or heard another car.

I again knocked off some time, pushing deeper into braking zones. VIR is starting to feel pretty home-y to me and I think I've found most of the easy "driver mod" time I had left on the table. The car generally understeered, and I dropped the front pressure about 2 psi hot (30F/32R) over the sessions. Here's the last session I have timed with my best lap - 2:25.3. You can see I tried to gently ramp up to warm up the tires - whatever it is about how I drive when I take that approach, it generally seems to stress the front tires less and gives me a more balanced car as the tires get heat soaked.



I'm not sure how much of it is due to the previously mentioned general understeer the car had and how much is due to the spoiler, but the car was so much more planted through the uphill esses. The model I bought is about a 2" tall spoiler, which theoretically should be enough to notice. I'm going to get to work on some sort of extension for it, be it plexiglass or 3d printed. For now I just put some painters tape over the holes while the paint cures a bit more.

She still rolls more than most track cars given my mild 550/375 springs and stock front ARB. Here I am at the top of Rollercoaster:



And going through the bottom.



I got a little loose when braking deeper into NASCAR bend.



And at the end I got to play with these two. All of us were pretty similar on pace. In one early session I was steadily reeling the Miata in and was expecting a point by soon when I overshot my braking point into T1 after the front straight and peeled off track for the usual 4-off checkup. I was proud of keeping up with a guy that had been doing Spec Miata literally for decades. That faded a bit when he said his tires were from 2017, but it was good fun nonetheless.



The Mini has been a racecar since the 70s, and it has a hot engine for sure. I gradually reeled him in, but it certainly wasn't on the straightaways. The owner just bought and thinks it will dyno around 120. The previous owner was in his 80s and was still racing it last year!

I do have video of the track day, including me laughing like a maniac while following the Mini that was three wheeling all over the track.



The Bad:

I pulled in with about 45 minutes left in the open track day because I felt something bouncing off my feet between my legs.



I decided to pull in to pit lane to fix it, and the car started running rough the moment it came to an idle. Crap.

I went back to my paddock spot, let it cool a bit while I put the loose module back in its velcro home, and it still misfiried. I swapped the coil, no change. It drove fine under load and made good power. With my rear pads shot anyways and already having 1h45 minutes of total track time, I called it quits I made it home with no check engine light if I kept it revved up at any stop sign.

Today I went to start it just to see. It cranked up, and immediately died.



I haven't checked the plug condition yet, or done anything else. These are the exact same symptoms I had prior to the rebuild, but worse, on the exact same cylinder. I'm guessing my cylinder 4 valve adjustment is whack.

Great.

 

Damn dude, was really amped for you while reading the first half of the post. That mini is rad and it's always cool having other guys to run close to on track. Also dang, 30 minute straight session and 1:45 total time on track, you were getting your money's worth there.

Did the engine sound normal while cranking? If cylinder 4 was low enough on compression to sputter at idle, I'd expect it to be audible every cycle while being cranked.

 

TLDR looks like half my intake valves are fukked.

Last night I pulled the plugs.Both 1 and 4 are running poorly compared to 2 and 3 based off of the soot.



Off with the valve cover.



I assumed it would be the exhaust valves that went bad, but no.




I stuck a borescope down the cylinders to see what I'd find. he faces of the cylinder 1 and 4 valves look to be cupped compared to 2 and 3. It's hard to get the camera to focus so close.

I'm not sure which most people prefer but somewhere along the way I switched from text below the relevant picture, to above. Miataturbos picture upload goes below, so that's what these get so I can keep track of which is which.


Cylinder 1 Above

Cylinder 2 Above

Cylinder 3 Above

Cylinder 4 Above

Not sure what step I should take next. I have other **** to do, and I would like to stop being a renter by this summer. A quick fix with an off the shelf reman'd head may be the move. As of now I have two Miata sized garage ornaments and no track car. And I don't want to miss another season of tracking. Sucks to throw out hundreds of dollars of new Mazda OEM parts with a cylinder head that may just need new valves but I don't know who I'd trust for a fast turnaround on this.

I'm pretty pissed that nothing I did or had any control over failed. It be like that sometimes. Did I ever mention I hate working on engine internals?

 

That sucks.

I'm not sure I can see "cupping" on the 1 & 4 valves, but they are definitely more silver at the edge than 2 & 3.

I'd say find a used engine and send it. I know nothing, but since it's on a pair of cylinders, I'm wondering if maybe when it got hot those two pistons kissed the valves by a tiny amount or something. I would simply hesitate to do another head swap on the same bottom end. I tried to go back over what you'd written, but I don't think I saw anything that indicates you would have decked the block or anything.

 

Basically it was just a stock OEM rebuild with the bare minimum of aftermarket parts

The blocks 0.50mm overbore pistons are the only noteworthy items. The head and block were skimmed just enough to clean and true the surface, no major change in compression. The cylinder head service was just a basic valve job, lash adjusted by grinding the valve tips, new OEM springs, and Viton valve stem seals from Miataroadster.

After last years experience with the import used engine, If I can't figure out a good path that involves this original short block, I'm thinking it gets an engine swap. $2k for another roulette game with a 20 year old engine that's also likely due for a rebuild has lost its luster.

The Ecotec has piqued my interest lately. 200hp out of a $500 used engine that can be found everywhere sounds great to me. I'd rather keep playing at stock power to have more context for how I'm improving as a driver, but more power needs to happen eventually.

 

Leakdown test should tell you more. I'd be confirming your valve issue before anything else, it's easy to jump to conclusions and miss something more simple.

Assuming a valve issue is confirmed start looking for a good used head, or find a shop you can trust with yours. I had my OEM head freshened up for $400 on my build and it was worth every penny.

Ecotec is cool, I love the idea too. But keep in mind no matter what you tell yourself it's still a swap, which comes with its own problems, teething, issues. You are almost there and it's gonna be near impossible to beat OEM BP reliability here if that's your goal.

 

Weird that just the intake valves would start having issues like that. I'm not doubting you at all, and you're obviously very thorough in everything you do, but the valves and seats were 1000% clean and seated when you measured lash, right?

I don't want to use personal experience as my only reference, but this experience I had while setting lash in my current car's first Duratec engine comes to mind:

Might not be directly pertinent to what's going on, as I'd imagine the lash would have tightened up in the first few revolutions if there was any carbon/debris holding them slightly open. It just seems weird that you'd have the intake valves start cupping or valve seats collapse almost directly after a rebuild...

 

I didn't do too thorough of an inspection of his work, but I did verify a fresh surface on both the valves and the seats, and measured lash multiple times on and off the block and at different temperatures. This is the only picture I have of the combustion chambers. I did not pull the camshafts out to give the valves a smack that would clear off any debris like I've seen you do on your Duratecs.



I figure that blue chemical residue is Prussian Blue to check seat contact area.

Since Facebook is a lot more active, I went and inquired with the hive mind there. I've learned some things that I'll take as fact from more experienced racers.

1. It's called a tulipped valve. I knew there was a better word for it.
2. The general causes are boost, insufficient seat pressure (especially with boost), worn guides, or just a bad valve job. I have no boost, I used new OEM valve springs, I did not ask for anything done on the valve guides, and I have my reasons to question the general quality of the machine shops work.
3. BP6D intake valves are apparently the worst for tulipping, the stock valve has a very small heat treated area, and if you blow through that with machining and don't heat treat again, tulipping will happen in short order. One guy mentioned that 90% of the tulipped valves he sees in Spec Miata are intake valves.

My guess is that door #3 contains the most relevant truths for me. I think the machining blew through the hardened area of the most vulnerable valves. There is no way forward other than replacing these valves and getting another valve job, or replacing the head. Adjusting lash will just result in the valves sinking deeper.

I've got three or fourish options I'm deciding between, in order of current preference.

1. Used cylinder head, if I can find one for a reasonable price that isn't the same as an entire engine, from a known Miata vendor or another racer. I'd throw that on with a minimum of changes. I'd check the flatness and lash preferably before I buy, and maybe new valve seals after.
2. New Reman head from a Spec Miata shop, assuming they are on the shelf ready to go. Treasure Coast wants $1600 with no core, and another person recommended East Street Racing. Rossini Racing is local to me and may be able to help, but I doubt he has stock on the shelf.
3. Complete used engine. I'm not going down the "JDM" route again, so again, looking for known names in the Miata community or trusted vendors.

4-ish. A new set of valves are $500 whether I go with Manley or OEM. I'm guessing there's a line at any decent machine shop, so rebuilding this head to get the car back on the road doesn't look like a great option if I want to run more events this year. If I go with a used head, and the short block proves itself over more time, I might eventually revisit this head.

​
Agreed. After all, that's why I've owned and modified this car for 10 years while sticking with a stock ECU. Proven reliability is my first priority.

I want to give this short block another chance and definitely am not looking to swap as my first option. But if I reach the point where if I can't be confident I'm getting a reliable BP without spending $7k for a fresh 130hp Spec Miata engine or paying $2k for a 200k mile used engine and hoping for the best, I'm going to be less interested in sticking with the BP.

 

I have a complete BP head on my shelf and don't own a miata anymore. Maybe I should take a look at it for you

 

If it's a BP6D VVT head, I could be interested. Two other gentlemen have offered to sell me spare heads from their racing stockpile, but neither are local so I'm not jumping on anything just yet.

 

It's not a vvt