Head F'd?
 

So pulled the head of this afternoon. Apparently metal got in there and beat it all to hell. Only cyl #2, the rest are happy. Really want to go punch the previous owner. So the question is fix this head (if it can be) or buy a bare head cheap somewhere and build that. The cylinders are slightly scored, just enough to feel with your fingers. I was going 1mm over bore anyway so at worst I just go a little bigger.
Pics--headphone jack for scale, didn't have a pen handy
https://www.miataturbo.net/attachmen...ine=1336878662
https://www.miataturbo.net/attachmen...ine=1336878662
https://www.miataturbo.net/attachmen...ine=1336878662
https://www.miataturbo.net/attachmen...ine=1336878662
https://www.miataturbo.net/attachmen...ine=1336878662

Also if anyone could answer this. What exactly does it take to put on a VVT head to a '99 block.
Complete head
Valve cover and the little hose thing on top
run the wires to a hydra for controlling VVT? +sensor

And are '99 heads better or VVT? I swear I read somewhere the VVT flows less but the VVT helps spool. If memory serve tho it's best to run '99 block and head gasket with a '01 head +coolant reroute. If it get swapped around

The head can be saved no issues, I have fixed worse ones.

A little work with a die grinder, and a surface and all will be fine, yes you will still have a few pits in the surface.

Why go 1mm/.040 get the block rough bored, but not honed, get the pistons, then have the block honed to set PTW clearance.

Head castings are identical. No flow difference between a VVT and a 99 head. VVT will significantly improve spool without any significant top end power loss. At this point, if you can afford VVT and you aren't doing it, you're a fool.

VVT swap requires:
-valve cover with oil control valve and oil feed line
-vvt head with cam caps, cams, intake cam gear
-brass oil feed line that connects into block

^Thanks. Sourcing a head now. Also I read somewhere that VVT heads can't use +1mm valves unless special pistons are used. Not concerned now but maybe later. But the valves themselves are the same 99-05 so if my sourced head has burned valves or worse missing I can use supertech valves.

I believe that 10:1 pistons can't use the +1 valve due to the piston dome shape. I have no experience with this though.

That was my thought. I figure if I found a head missing or with F'd valves I'd go +1mm since I'd have to buy valves anyway. It'll be 99 bottom (assuming the block is ok) and VVT head. Looking for 9-1 comp pistons. With the block scoring I may have to go bigger. As cheap as blocks go for I don't mind maxing out the bore but dont want paper thin cylinder walls. My funds for this build are getting smaller by the week as life takes chunks out of it. So the sooner I get this built the better. Finding +1.5mm Pistons seems to be a pain. It looks like a +1mm bore "might clean up the scoring, a +2mm would. Like I said I can just feel it catch the tip of my fingernail when I run it by the marks, or feels slightly ruff on the finger prints.

I really don't think it's that critical. You're maybe not going to get an absolutely perfect seal, but I can't see that making a hell of a lot of difference.

Back about 20-25 years ago, my dad aquired yet another Studebaker. This one was a 1962 Lark, with a small (259?) V-8. It was seized, as someone had let water get in the motor. We removed the pan, crank and the heads. We then proceeded to use a block of wood and a sledge to smack the pistons out of the bores. We used a hand held hone and a ridge scraper to clean up the bores. Next we put new rings in it, reassembled (not even new bearings) and it cranked right up. Dad ran that car as a DD for years, and it never smoked or burned oil.

Zombie.... 1mm is a big over bore and 2mm is huge!

most blocks can be ckeaned up at a .5mm=.020

1mm=.040

1.5mm=.060

With what you are discribing on how bad the scoring is, I bet a .5 or .75mm would clean the bore up.

Best thing to do is take the block to the machine shop, get it rough bored.

Tell the shop to call you with the over bore size, then order the pistons

once you get the pistons, take them to the machine shop and have them hone the block and set the PTW

truthbomb.txt

Same place I'm getting pistons from is doing the work. Just finished tearing the block down. No idea where that piece of metal that came out the oil pan came from. Pistons and rods look OK. I though the metal made it past a piston. Doesn't look like it but maybe I'm missing something. I'll clean it and see. Getting the VVT plug from a harness so wiring will be pretty like stock. FM will send me the map for it. Just need to dig around d to see if my COPs will fit, I'll machine the stock cover bugs off so my bracket fits. No funds for LS coils. COP setup is in the drawer. I am definatly going to blow this 5sd this summer.

Bogus-thanks for the input.

Let me dig around... I may have some coils from a LS3 I can part with on the cheap...
You have the coil oe # or a pic?
Or work a bit of a trade on the beat up head.....

COP number 90080-19015. All work and in really nice shape. I shaved just a hair off the sides so they would sit all the way down. I have the factory pigtails wires to factory 99 coil pigtails and capacitors wired in to. Wired for wasted spark. And the TSE COP bracket too. Was going to re wire for sequential. If I keep them I may figure out how to make the dwell reduction thing and put them on my 97. In fact if I keep the head that's what will get it when it's rebuild time. And with my luck will be soon. It's burning a little/bunch of oil too. It had a hard life before me. But for what I paid years ago I'm okay with rebuilding that one with a power drill. Its the daily beater, flat black and all. Really doesnt look like a 30yr olds car, or for that matter my wife is driving it a lot and gets funny looks.

Sorry, I guess I forgot how I wired them. The COPs are on factory Toyota pigtails and the other end is on 3 pin weatherpacks with capacitors in the COP harness. Also I made a 3 pin weatherpack to factory '99 coils adapter. basically the car harness is on weatherpacks and I made adapters to swap back and forth if anything ever went wrong.
Need to clean up my wiring at the ends a bit, my buddy calls me crazy ---- retentive. I have to rewire for sequential anyway.
https://www.miataturbo.net/attachmen...ine=1337016963

I ran 1mm oversize valves in a VVT head on a stock 10:1 "VVT" bottom end last year.
No issues with contact, it was a collapsed lash cap and subsequent cracked retainer and dropped valve that made it break.
How much you can advance the intake cam with much less clearance (11:1 ST and decked flush), I'm hoping to learn during the season (waiting for parts while the race weekends pass is frustrating).

I'm bumping this to avoid making a new thread. Any more word on VVT head with +1mm valves working with 84mm 9-1 Supertech pistons. Getting ready to send the head off. Little bit of port work and a rebuild. Would like to just throw in the +1mm valves so I can use Inconel on the exhaust side (supertech doesn't make inconel stock sized that I can find). Would like Inconel for indestructability. Just going to overbuild this as funds allow and weld it in the car. Really don't have the funds to have the motor clayed and all that, especially if it won't work. I can swing the few dollars for +1mm, doing new valves anyway.

You could duplicate Jkav's head:

Some light reading on valvetrain hardware, VVT head-centric - MX-5 Miata Forum

isnt this what sandpaper and a honing tool is for?

I I skimmed through it twice. Good write up, but didn't see anything confirming what pistons check out.

I find it hard to believe that you can afford the Inconel +1 valves, but you can't afford the cost of getting it clayed. If you are going to get extreme with the lift/valve size, you really need to clay everything to ensure that the clearance is acceptable, especially if you've skimmed the head or decked the block.