I don't like having my head at risk. I specifically sought out an NB1 solely for the head. It's integral to my plans, and BP4Ws go for stupid money by themselves, like... about as much as i'll have the car out of pocket after i sell off some of the crap i don't care about.
That said, this thread has relieved me. 97k miles? I'll beat it as hard as i can. 
The BP4W had the shortest production run of all Miata engines, the highest mortality rate and is the most popular to swap into earlier years. Thus the value.
Hey, Camaro Z28s are worth as much as their engine and transmission as well
Keith Tanner wrote: The BP4W had the shortest production run of all Miata engines, the highest mortality rate and is the most popular to swap into earlier years. Thus the value. Hey, Camaro Z28s are worth as much as their engine and transmission as well
Yep! That's exactly why i just bought a whole car to get one.
My "dream list" was an early 90 with a BP4W, 6spd, and 4.10 Torsen. But pricing that out got ridiculous. Was way easier and cheaper to just go a decade newer, not worry about the weight, and bend a little on the rear ratio. 
In reply to Swank Force One:Don't forget the safety switch. In fact I'd say that for every stick shift car out there! That's cheap insurance for the transmission on almost any stick shift ride. Starting in neutral with the clutch out is good to get that oil moving!
Rupert wrote: In reply to Swank Force One:Don't forget the safety switch. In fact I'd say that for every stick shift car out there! That's cheap insurance for the transmission on almost any stick shift ride. Starting in neutral with the clutch out is good to get that oil moving!
Yeah i'm doing that regardless. 
Yeah, when the J-H sits for too long (happens too damn much unfortunately) oil will of course drip back to the pan. Therefore, EVERY time I start it the trans goes to neutral and stays there until the oil pressure comes up.
Little 'clutch switch' tale: I had a customer, petite woman, who was into horses big time, so she had a Ford dually diesel. It got towed in three or four times for a no start, she simply could not push the clutch all the way to the floor for the starter to work. The last time, I asked the shop foreman if the clutch switch was adjustable, unfortunately no. So I made a little jumper wire, plugged it into the rear of the switch connector and sent her on her way. 
jstein77 wrote: So that eliminates .0001% of all clutch depressions?
It eliminates almost 100% of the ones that happen with no oil pressure.
It also allows you to move the car when the fuel pump dies. (Scene: Knurled "driving" a Subaru down the road with the starter and the trans in 5th gear, because he didn't feel like pushing it a block to his driveway)
Toyota trucks have a little clutch switch override button on the dash.
Chas_H wrote: In reply to evildky: Fix what? The results of a failed thrust bearing are catastrophic. The fix is an new engine.
Nah, you just have to replace the thrust bearings and crankshaft. The block is usually okay.
Chrysler still lists a service kit for when the thrust bearings die in the 2.4. It's some bearings, some seals, and a crankshaft. The clue is when it keeps blowing the front crank seal out - the crank walks backward, oil gets between the oil pump and seal, when you push the clutch down it pushes the crank forward and shoves the seal out.
Way cheaper than a new engine. Heck, I did one where the crank was still good, just new thrust bearings and keep on truckin'.
In reply to Knurled:
Chrysler isn't Miata. Miata engines with a failed thrust bearing are junk.
Knurled wrote: Nah, you just have to replace the thrust bearings and crankshaft. The block is usually okay.
It completely depends on worn it is and whether or not the crank had a chance to machine the block. If you catch it when it's just a bit over spec, but nothing touch anything yet, then it's just a new bearing. Otherwise...
I tore down a Miata engine with a thrust bearing failure once (out of a 94). The bearing had fallen out into the pan and gotten turned into a pretzel by the crank. The crank had machined a 1/8th inch groove into the block and main cap, and just about every oil passage in it was clogged with little bits of iron. A spun main bearing is what killed the car, but once it was apart it was apparent that the pistons were trash, the bores were trash, the cam journals were trash, etc.
Keith Tanner wrote: The BP4W had the shortest production run of all Miata engines, the highest mortality rate and is the most popular to swap into earlier years. Thus the value.
So hypothetically, if you catch it before failure and can save the head, what's the going rate for a remanufactured short block?
Keith Tanner wrote: Toyota trucks have a little clutch switch override button on the dash.
I wish they all did! Of course in Europe that isn't a problem. It's just another one of our nanny rules here. If we're too stupid to start a car without a "safety switch," we really shouldn't be on the road!
Woody wrote:Keith Tanner wrote: The BP4W had the shortest production run of all Miata engines, the highest mortality rate and is the most popular to swap into earlier years. Thus the value.So hypothetically, if you catch it before failure and can save the head, what's the going rate for a remanufactured short block?
Dunno. I deal in better than stock But at that point, you can start playing Parts Bin Interchange Bingo. Want lower compression? Get an 8.8:1 1994-95 bottom end. More compression? 10.5 2001-05 non-turbo. Even more? 11:1 JDM 2001-05.
I was planning on doing a timing belt this weekend, so I guess there won't be an easier time to measure the crankshaft end play. Of course, with 114k on the engine, I'm guessing that it would have failed by now if it was going to.
Keith, usdm vvt motors are 10.0:1 as far as i know. But if the jdm y0 stuff is 11:1 then i guess i should start shopping.
Ah, whatever, it's been a long day. You get a refund on that 10.5 info. But yeah, some of the late JDM stuff is apparently full of magic fairy dust.
Trying to decide between jdm y0 pistons and a head shave or just some 12:1 Wossners.
Watch your quench space when dealing with big head shaves. Generally, pistons are the smarter way to go.
Keith Tanner wrote: Watch your quench space when dealing with big head shaves. Generally, pistons are the smarter way to go.
Yeah... Quinn seems to be doing ok with vvt pistons and a 60 thou shave but i think i'd be happier with maybe at least the jdm pistons and a smaller shave. He's doing 172whp and beats the car hard. I'd be fine with that, but have to wonder if just getting 12:1 pistons would be smarter anyways, since it would leave me in theory with an extremely durable motor. Shave motor is way cheaper though. Until it blows.
Thoughts for fall.
If it warms up a little (it was -12 here this morning), tomorrow I'll start the timing belt job on my 2000 Miata. I've borrowed a dial indicator and I'll measure the thrust bearing endplay. I'm curious to see how this turns out, as the car has 114k miles, hasn't made the noise described in the TSB and hasn't threatened to stall with the clutch in.
Keith Tanner wrote: Watch your quench space when dealing with big head shaves. Generally, pistons are the smarter way to go.
My brain isn't wrapping around this. Decking the head should not affect quench distance because that is solely determined by how for down in the hole the piston is (or isn't: VW likes to make their pistons proud) and how thick the head gasket is.
Is there something else that I'm missing?
I think the theory is that the diameter of the combustion chamber in the head is changed. Reality seems to be that cam timing is the bigger issue.
Okay...I have the front of my engine stripped down to change the water pump and timing belt. I have a dial indicator with a magnetic base, but I'm not sure what the best way is to measure the crankshaft endplay with the engine and transmission in the car. I can tap the crank nose rearward with a polyurethane mallet, but what's the best way to move it forward? Will pushing the clutch pedal in be enough? I really don't want to put a prybar behind the pulley.
Knurled wrote:Keith Tanner wrote: Watch your quench space when dealing with big head shaves. Generally, pistons are the smarter way to go.My brain isn't wrapping around this. Decking the head should not affect quench distance because that is solely determined by how for down in the hole the piston is (or isn't: VW likes to make their pistons proud) and how thick the head gasket is. Is there something else that I'm missing?
Depends on the head. If it's one that goes flush with the machined surface, it won't make any difference. On others, there's some volume all the way around. You take this away, you lose quench space.
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