I called the machine shop. He said he's done hundreds of Miata motors over the years. 450 for valve job, new seals installed, valve lash set. He said he doubts it'll need valve guides. Going to try and get it over there this week.

 

Personally, I'd never service a miata head again without doing the guides even if they are "in spec". This is coming from personal experience, where the shop told me that (so we didn't replace them) but the motor has a obvious valve seal leak (with supermiata valve seals, that should not leak!). I've read around the forums over the years that you should always replace 'em or else the looser tolerances might allow valve stems to leak, and once you are in there (and esp if you already bought the guides) they are easy to put in.

 

Good to know. I ordered them, I'll have him put the new ones in as well.

Quick question about Flow Force. When I dropped the spacers installing the injectors I ordered 2 3 packs of the spacers. I haven't gotten shipping on them 10 days later. Is FF known to take forever processing orders? On the page for the spacers there's a review that said they never received them.

 

FF makes good producs but are terribly slow processing and shipping stuff out. You'll get it, but the slowness is normal. I once ordered plug wires from them that I needed for a track day, I paid for overnight shipping after confirming with their support that the product was in stock ready to ship. It took them 5 business days to get the order out even then, fortunately I got them (barely) in time still. Was very annoying to pay more for shipping than the item cost only to have them take their sweet time getting it out to me. But I've had good experiences with their products, so worth it.

 

Been looking for proper ring gap info, just like everything else it depends who you ask (or who's post you read). One thing most people agree on is the 2nd ring gap should be bigger than the top by .02-.04?

Top: 0.15 - 0.30 mm / .18 - .20 for boosted?
Second: 0.15 - 0.30 mm / .20 - .22 for boosted?
Oil Rail: 0.20 - 0.70 mm / .22 - .24?

 

Yeah, most folks are going .002" larger for the second ring than the top ring.

.018-.020" top and .020-.022" is pretty standard for boosted BP's. I think I did .019" top and .022" bottom on mine with no issue. Others will likely chime in too.

 

I like .019 and .022, thank you. Having never done this I'm spending literal hours everyday researching. At the end of the day the info you guys give me is what I'll go with but I just like to gather as much info as possible, then bring what Ive learned here and cross check that info with you guys. The thing I have to keep reminding myself is most if not all of you guys are building to race, at the moment I have no plans to but I live 30 minutes from Hallett so that could always change. It's a street car that'll rarely if ever see a 7k redline. I think the only other thing I may do just for peace of mind is heavier valve springs but idk if the return is worth the extra $500+.

 

It’s not. You’re not using the rpm, or increasing it. I’ve got stock valve springs in my 300+ build that I’ve tracked occasionally with no issues. Ive got a ton of other non-tracked and tracked turbo cars for data points, all with stock springs. None with issues. Not saying there’s no benefit or risk to using them, but in my experience, upgraded springs aren’t worth it for a street car.

 

Just to echo Curly, my (mostly) track 300+whp car runs stock springs with no issues. I keep the rev limit stock though, if you want to rev higher you definitely want to look into springs. Most tracked turbo and NA miatas I've seen are on stock valve springs as well.

 

Not that additional data is needed at this point, but I ran my stock-motor turbo NA8 at the track for a year with stock valve springs. Prob 10-12 events total. 7k redline. No issues.

 

Sticking with stock springs. Thanks guys. I don't really know what my goal is for the car I don't really have a HP or psi goal. I liked the way she felt at 12 psi before she died on me so I'd be happy there and feel pretty confident the new rods will be more than enough to keep me safe there.

I do have questions about torque on head, rods and main. I've read so many different things.

Rod bolts: 43 lb/ft - also read 44 lb/ft + 90° turn - also read 45 lb/ft, fully loosen and go to 45 lb/ft again.
Main and head bolts seem to be 60ish lb/ft ?

 

Cleaning the pistons. Will this work?




Rods came today. Torque specs for the 3/8 arp bolts is 43.

 

What rods? Are you using forged rods or factory? Factory is 35-36ft/lbs. Good idea with studs is to torque them to set the stud, then loosen them. At least thats what I've heard, no idea if it does anything, but it's easy to do.

Factory mains are 40-43ft/lbs, factory head bolts are 56-60ft/lbs.

This all changes if you're using non-factory hardware. If you go forged rods and ARP main/head studs, it's easy to remember, everything is 60ft/lbs.

Edit: oops, looks like ARP now says 65ft/lbs for head studs. Better than a few years ago, they used to suggest 80ft/lbs. That's definitely wrong.

 

I bought Eagle Forged rods. Part #CRS5233M3D.
The instructions say to use the oil and set them to the required torque. I did read where people said to set them, back them out then set them again. I think the oil they provide makes it so you don't have to do that. Provided you use it correctly.

I read through the whole thread about ARP torque settings. Really interesting read and lot's changed over the years. I will be using ARP for the rods (that's what they came with), head (got new in box when I bought the motor), and the mains (I still need to order them). The majority seem to think ARP bolts are overkill for the BP motors but everyone still used them because they could be reused. When I saw 80ft/lb for the head studs I knew that had to be wrong.

 

Concerning head and main studs. Posting this for future reference:


So 45 for rods, 60 for mains, 65 for heads. I have to say, 60 for mains with more clamping pressure with arp over stock seems excessive. even at 45 you're going to have more clamping pressure than the stock bolts at 45.

 

Another delivery. I expected the valve seals today as well but I guess they're going to take an extra day.

 

I've been going back and forth about replacing the oil pump rather than using either one from a failed engine. Is it a good idea to go with a boundary pump for boosted applications or is that just marketing and the OEM pump will be fine?

 

For a street car, the OE pump is fine, but not if it's been through a engine explosion. The tiny relief piston see unfiltered oil, and if any debris scored the bore and eventually jams it, you're left with zero oil pressure. I've seen it, not fun. IMO the $340-$450 for a boundary is worth it, unless you have a good condition stock pump available. $450 is the VVT pump, if you don't have VVT, the $340 pump still has the billet gears and is plenty.

 

Alright curly I'll order a new oil pump as well. Thank you. I've been going back and forth but reading stories of guys rebuilding their engines and having a failure 100 miles after getting it running has me wanting to do everything possible to avoid that. I have a feeling when all is said and done I will have more time into cleaning than actually building. I'm ok with that.

This "budget" build is getting expensive lol. I could have paid 2000 for a JDM engine and been done with it. But I wanted the experience of rebuilding the engine, and I still would have put forged rods in a JDM so it's going to be a wash.

 

With the "JDM" engines, you still need to reseal the oil pan, replace water pump and timing belt components, and anything else dry and crusted. They're still 25 years old. And like you said, you wouldn't have billet oil pump gears, forged rods, new piston rings, etc. Plus UK/Japan engines can arrive quite rusty, so you're spending a lot of timing wire wheeling and painting.