Removing Valves from the Miata cylinder head

The '94 runs well but not like it did back in the day. My goal is to get it back like it was, and make it run like a scalded cat on the track again. So I'm starting on this extra head I've had in the cabinet for the last six years. The mating surface needs to be cleaned up so I'm going to take it to a machine shop to get planed and cleaned and the valve seats re-ground. I can to do the reassembly here and then I'm going to yank the motor and swap the heads out of the car so I can also address the leaking rear main seal, install a light flywheel, new clutch, new timing belt, water pump, and front main seal. I don't believe the bottom end needs a rebuild, however. The existing timing belt only has about 30k miles on it but if I've got it all apart I'm going to replace everything I touch.
So today I disassembled this '96 head with 60k miles on it. I bought it on eBay about six years ago and ended up not using it, so it's been sitting in a cabinet ever since.

RAM iPhone, Camera, GPS mount

iPhone and camera mounts for motorcycle, from RAM
I got mine from Amazon for around $30. Very well made piece of hardware and works great. I do not think my phone is going to fall off in normal riding conditions. Of course it's not waterproof so at the first hint of rain the phone or camera have to get put away. I believe they do offer some waterproof options.

aSmartHUD app for time/speed/distance/music

MotionX GPS app for navigation

Standard camera mount

Fully articulated arm. Swapping camera and phone mounts takes just a few seconds.

Acceptable jacking points on a '90-'05 Miata

I lifted this image from a post at Miataforum and added some additional jacking points that weren't called out in the original image. You can tell which ones I added because they look like they were drawn by a 6-year old.

The four inner-most points indicated in the image are at the ends of the "frame rails" which are actually just floor panel stiffeners. Jack right on the ends of them where they are stronger, where the yellow ovals are in the image.

Bremmers for the Bimmer

So it was time for some new tires for the M3. The Nitto Invo tires it came with were almost down to the wear bars and getting really hard and noisy. I had put almost 20,000 miles on them and they weren't close to new when I got them. I took the opportunity to update the looks of the car as well by adding a set of Bremmer BR05's to my order from The Tire Rack. The BR05 is basically a reproduction of the wheels BMW put on the CSL version of the M3. Well, not really a reproduction but I guess a reasonable facsimile without the associated cost. These are only about $660 a set in 18" size. They are 18x8 in the front and 18x9 in the back, exactly like the factory wheels my car came with. I think the offset in the front is a little bit less than stock because it looks like the wheel sticks out just a bit more. I'll have to look up the exact numbers and see for sure.

Click for full size photo

The black finish is something different for me and I really like the slim machined lip around the outside of the wheel face. The tires are Sumitomo HTR ZIII in 225/45ZR-18 in the front and 255/40ZR-18 in the back. They came perfectly balanced from Tire Rack and ready to mount. The Sumitomos are an underrated tire in my opinion. The Boxster I had came with them and I thought they were great, and the price is very reasonable at around $600 for the set in M3 sizes. They aren't for autocrossing or track days, but for street driving they are a great value.

Miata Battery Alternatives

Early Miatas came with an excellent AGM type battery that has been known to last upwards of 10 years with proper care and feeding. As nothing lasts forever, sometimes a replacement battery is needed. I've relied on a battery from Westco for many years. It's pretty much a direct fit for the Miata and uses the same AGM technology which is better and safer for the Miata's battery location in the trunk of the car.
As much as I'd like to continue to buy Westco batteries, I have to be fiscally responsible and ensure that I'm getting the best value for my money. So, I shopped around and found the Marathon battery being sold on Amazon.com by a company called Battery Mart (just search for "miata battery" on Amazon and it will come up). It is an AGM battery and with the exception of the top cap, looks to be pretty much the same battery as the Westco. The part number - 8AMU1R - confirms it. It's the same East-Penn Deka battery as the Westco. The Marathon version was $79.95 plus $23.50 for shipping. The Westco generally sells in the $120 range, before shipping, however I did find a good deal here at $99 and $9.95 for shipping, which puts the Westco only $10 more than the Marathon.

Correct size and the posts on the correct sides for a proper fit in the Miata. This one is going in the '99.

Side-by-side with the Westco, the similarities and slight differences are obvious.

The service from Battery Mart was good. I ordered the battery on Monday and it arrived on Thursday, triple-boxed and well padded.

Just a point in time.

Miata A/C Evaporator Replacement

It's been at least a year since the A/C in the '94 Miata blew cold. It just gradually faded out so I didn't really notice for a long time, until I realized it was really damn hot in the car all the time. I thought for a while that I was going to have to take it to an A/C repair shop, which really goes against my grain. I also knew it would be expensive. At some point, though, I had a revelation. That revelation told me that fixing the A/C was no different from fixing anything else. All I needed was the right tools. A quick check online showed me that spare parts for my '94's A/C system were pretty cheap. I wanted to do it right so I needed the proper tools - a manifold set and a vacuum pump. I already had the manifold set from a previous effort at diagnosing an A/C problem in my old truck, and an appropriate vacuum pump can be purchased at Harbor Freight for around a hundred bucks, which I did.

I'll skip over how I diagnosed the problem, but suffice to say I figured out the problem was the expansion valve. When I went to order a new one for $25, I found that a new evaporator core was only $50, so I ordered one of those, too, just for good measure. Finally, because everyone says you should, I ordered a new receiver/dryer for about $15 and a bag full of o-rings for $3.
This post isn't meant to be a detailed how-to, but it is a "you can". This job was dead easy, except for crawling up under the dash to yank the old evaporator core out. I used this tutorial to guide my actions and it was very applicable to my Miata. The evaporator core is housed in a black plastic box, bolted to the firewall right behind the glove box, with two small 10mm nuts. On the right, it connects to the blower housing. On the left, the center air control unit. Two aluminum pipes stick out through two holes in the firewall, where they connect to some more pipes that go to the compressor and the condensor. I didn't need to mess with either of those things. I disconnected those pipes, unbolted the box, released the clamps that connect the box to the left and the right, and yanked. With a little persuasion, being careful not to damage any aluminum bits, it came out. The evaporator box is held shut with some metal clips that pop right off with a screwdriver, and two screws. The whole thing clams open and you can pull the core right out.

The old and new evap assemblies. After I assembled the expansion valve to the core.

Here's the old core.

Here's the new core with the expansion valve all connected up, set into the lower half of the box. There's a temperature probe that is wrapped to the big tube.  Ok, actually, I don't know what the hell that does. I just connected it up like the old one.

Here's the whole evaporator assembly ready to go back in.  I just had to be careful sticking those aluminum tubes through the firewall, not to jack up the threads.

Here are the connection points just ahead of the firewall in the engine compartment.  They were misaligned quite badly and took some persuasion to get threaded.  Then I initially forgot to tighten the big one down all the way, which became apparent later when I tried to put a vacuum on the system.

Ahh sweet vacuum.  This is what you want to see when you run the vacuum pump. The inside numbers read vacuum in units of inHg (inches of mercury). You run it for about 5 minutes at first. Then you want to stop the pump and wait 10 minutes and hopefully your vacuum doesn't go away. If it does, there's a leak somewhere. I had a big one, but it was easy to find and fix. Then I let the pump run for a good half-hour.

Hard to get it all in the picture but this is how the vacuum pump is hooked up. The blue line is the low pressure side, the red is high, and the yellow line is the line through which you apply vacuum, or feed refrigerant.

Here's where my running pressures ended up after adding 22 ounces of refrigerant and two ounces of oil to the system (I'm banking on there being some old oil left in there). I wanted to see more like 200 psi on the high side, so I may need to add some more R134a, or possibly my compressor isn't strong. We'll see how it cools over the next few days. It felt pretty cold just running it in the garage.

So to sum up, this was an easy project that should make my '94 a lot more comfortable in the Florida summer, which is fast approaching. I commute almost two hours every day now, so having this A/C working is going to be pretty important.

Another iPhone HDR photo

Ninja 250R

M3 HDR photo

I bought a great HDR photography app for the iPhone. It lets you really tweak the photo after you take it. It doesn't just simulate HDR, it really takes two photos and melds them together.
Nothing significant about this photo other than playing with the HDR app.