In reply to Ranger50 :
He didn't ask so I didn't offer. There were some upgrades we agreed on and he got whatever money he asked for. I have a few decades of experience in purchasing and don't screw my suppliers. When a price increase comes up my response is that it does me no good to save a buck now and put my partner out of business. In this case we parted good friends and I recommend him to others. So shame on you for the false accusation. You owe me an apology.
In reply to Brett Tower :
You can do other tests. It would be best to get the valve lash correct first though. I thought these were hydraulic, is there a chance the lash will be OK with oil pressure? Anyway, checking manifold vacuum at idle and above 2000 RPM might tell something. And with an older car I would look for vacuum leaks before pulling the head. Then a leak down test to see condition and find source of leaks. My suby showed the cracked ring land issue on leakdown, the hiss thru the oil filler cap was crazy loud.
We are back to the issue, no one wants to do the diagnostic work on a car. Just plug in the computer and replace whatever parameter is out of spec. But you can do a lot with basics and patience.
By "front to back" do you mean intake and exhaust?
Do a proper diagnostic first, before you pull the head.
Pulling cams and setting valves is easier than swapping a head.
Even if you can't get them shimmed right, you may be able to just pull the shim out so the valves seal again (not super familiar with this particular engine). Don't run it like that but just crank it for a compression test.
Do a proper compression test. All plugs out, throttle open. Do it wet and dry. If it gets better wet, then your rings are toast.
If it's still low with valves closing, pull the head and have it done.
If it's good, buy some shims and a service manual.
Yes, but more expensive.
I found this after a quick search.
https://www.miataturbo.net/engine-performance-56/nb-valve-clearance-adjustment-mazda-sst-95579/
In reply to ShawnG :
I'm leaning toward the "just go ahead and shim it" school. I've done it before on motorcycles. The thing that has held me back is that three of the valves are negative. That means I'll have to pull the shims, put in small shims, button it back up again and remeasure the lash before being able to figure out the actual shim size needed. Not really that hard or complicated. Just fiddly. By the time I screw around finding somebody and getting them to do it, I probably could have done it myself three times.
Brett Tower said:Just bought an NB1 for an amazing price. Seemed to run fine, but idle was set high. Didn't think anything about it as it had obviously been completely fettled otherwise with half of the Flyin' Miata catalogue, good paint and reuphostlered interior and new top.
However, once I set the idle down it had a rough idle.
Long story short: valve lash on intake valves was low or negative. Lash on exhaust was generally too tight. Low compression on most cylinders (even though it seems to run well once revved).
My thinking is that it needs the head pulled and checked over. If its been running this way for awhile (obviously, that's why I got it so cheap and the idle was set high to hide it) I'm concerned about the intake valves.
Problem: hard to find anyone willing to pull the head. Most shops I talked to said some version of; we don't do that anymore.
What gives?
Adjust the valves and go. If you adjust the valves and still have compression issues, NOW worry about pulling the head.
The problem is that it's hard to make a business case for working on 20+ year old cars. You can do it but you really need to have a passion for it. If you just want to make money there are less painful ways to do it.
Yes, I agree with the economics of it. I was spoiled by living in central Florida and having several excellent old school mechanics (pre pandemic) who I could use. That greatly influenced what I was willing and able to do vis-a-vis car buying and selling hijinks. (Sigh). Different world in the big city. Just got to suck it up and get on with it.
Without being excessively dramatic (not really), we are kind of living in the end times of the internal combustion engine and a world that I once adored. Don't sell anything. They'll never make anything like it again.
In my experience a larger gap did not affect idle or regular drivability. And definitely not compression. If clearances are too tight and the engine is warm it might hold a valve open, but I would bet as long as there was some clearance idle and compression test should be fine. I would be looking elsewhere. Vacuum leaks and maybe pull injectors and have them checked out.
My local repair shop I took vehicles to for state inspections would just ignore my requests for anything other than simplistic work. The a/c compressor in my truck failed. I asked them for a quote to replace it. Crickets. Same thing about the leaky oil filter housing on the wife's Jetta. "We'll get back to you with a quote". Never materialized.
I take my stuff to a different shop now that is happy to take my money. They actually ask me to source the parts for my weird old stuff so they don't have to be bothered.
I felt truly fortunate to find a little alignment shop that didn't bat at eye at doing my '66 Falcon with the Shelby drop.
I've talked to a number of classic/antique car owners that can't find anyone to perform simple repairs on their stuff. It has me considering a part-time gig after I retire keeping old stuff properly tuned for folks. But, the liability aspect usually shoots that down.
Ranger50 said:Then we can talk about the "technicians"... Most of them couldn't diag if a dog was dead. Anything more than a simple part swap escapes them. Same thing here. The act is simple but the execution/solution is complex. It is why you can't find a decent transmission rebuilder under 50. If I do find one, so many corners are cut to make a finished product, I may as well resort to just fighting trying to get good jasper units.
I'll find you a good transmission rebuilder under 50 easier than you'll find me a tech over 50 that can diagnose and repair a can bus system efficiently.
Older techs know how to rebuild transmissions because it used to be a valuable skill, not because they were or are smarter than current techs.
This discussion leads me to realize why I had the Clem for a month to repair a few small issues and they were perfectly happy.
Appleseed said:Wod it be easier to swap a known good head, then take your time finding a good head rebuilder for the original while you drive and enjoy the car?
For that matter a used engine might be an even better option as it would be plug-and-play.
1SlowVW said:Ranger50 said:Then we can talk about the "technicians"... Most of them couldn't diag if a dog was dead. Anything more than a simple part swap escapes them. Same thing here. The act is simple but the execution/solution is complex. It is why you can't find a decent transmission rebuilder under 50. If I do find one, so many corners are cut to make a finished product, I may as well resort to just fighting trying to get good jasper units.
I'll find you a good transmission rebuilder under 50 easier than you'll find me a tech over 50 that can diagnose and repair a can bus system efficiently.
Older techs know how to rebuild transmissions because it used to be a valuable skill, not because they were or are smarter than current techs.
I taught myself how to rebuild a C4 automatic. I know it's a pretty simple transmission, but it was still a whole new world to me. And, it actually worked when I was done with it. I was 58 at the time.
Do not ask me to diagnose electrical crap on new vehicles. Can't. Won't learn. Don't care. I'm affluent enough to pay someone, if that someone can be found. Problem is, I'm not sure there are that many 'someones' out there.
NOHOME said:Appleseed said:Wod it be easier to swap a known good head, then take your time finding a good head rebuilder for the original while you drive and enjoy the car?
For that matter a used engine might be an even better option as it would be plug-and-play.
You guys really like making mountains out of molehills.
In the time the O.P. spent replying on here, he could have had the shims out.
Why not just buy a new car with a warranty? Might be the best option.
ddavidv said:1SlowVW said:Ranger50 said:Then we can talk about the "technicians"... Most of them couldn't diag if a dog was dead. Anything more than a simple part swap escapes them. Same thing here. The act is simple but the execution/solution is complex. It is why you can't find a decent transmission rebuilder under 50. If I do find one, so many corners are cut to make a finished product, I may as well resort to just fighting trying to get good jasper units.
I'll find you a good transmission rebuilder under 50 easier than you'll find me a tech over 50 that can diagnose and repair a can bus system efficiently.
Older techs know how to rebuild transmissions because it used to be a valuable skill, not because they were or are smarter than current techs.
I taught myself how to rebuild a C4 automatic. I know it's a pretty simple transmission, but it was still a whole new world to me. And, it actually worked when I was done with it. I was 58 at the time.
Do not ask me to diagnose electrical crap on new vehicles. Can't. Won't learn. Don't care. I'm affluent enough to pay someone, if that someone can be found. Problem is, I'm not sure there are that many 'someones' out there.
I did my first transmission back when I was 21(?) and it was an AOD which for the time was utterly complex. I did all the upgrades I could rummage and afford at the time including a trans brake, 7 plate direct, spiral lock on the front drum, etc... still have the trans and still ain't used it. LOL and I'm 48 now. The new 10spds in the GM and fords don't scare me. My 6L80 out of my Avalanche I would have rebuilt at home if I had the time when it decided to weld itself together instead of putting in a used JY unit that's starting to give some funky shifts now.
I don't exactly like electrical and chasing down those gremlins, but it really isn't that hard. The factory procedure is out there in finding the culprit. Making it not be looking like a hackjob is what is hard to do and is off putting to most everyone. I understand CAN bus because well most of the aftermarket ECUs have taken it up for multiplexing in other needed modules and complete system integration even though they can still be standalone.
ddavidv said:1SlowVW said:Ranger50 said:Then we can talk about the "technicians"... Most of them couldn't diag if a dog was dead. Anything more than a simple part swap escapes them. Same thing here. The act is simple but the execution/solution is complex. It is why you can't find a decent transmission rebuilder under 50. If I do find one, so many corners are cut to make a finished product, I may as well resort to just fighting trying to get good jasper units.
I'll find you a good transmission rebuilder under 50 easier than you'll find me a tech over 50 that can diagnose and repair a can bus system efficiently.
Older techs know how to rebuild transmissions because it used to be a valuable skill, not because they were or are smarter than current techs.
I taught myself how to rebuild a C4 automatic. I know it's a pretty simple transmission, but it was still a whole new world to me. And, it actually worked when I was done with it. I was 58 at the time.
Do not ask me to diagnose electrical crap on new vehicles. Can't. Won't learn. Don't care. I'm affluent enough to pay someone, if that someone can be found. Problem is, I'm not sure there are that many 'someones' out there.
The problem isn't learning it, the problem is the value of knowing it. If a tech makes more money swapping transmissions, that's what they will learn to do. Given the time it takes rebuilding things, that's why power trains are swapped as a unit instead of repaired in modern cars.
In reply to alfadriver :
We do zero internal transmission work aside from replacing wiring harnesses. If it has to come out, we ship it off to a really good trans shop we know.
Internal engine work is also a no go because we have to warranty it. If it's more complicated than gaskets or simple parts swapping, we don't do it. This isn't a "can't do it" but a "can't economically justify it". If we have to pull heads, there are no good machine shops in the area, and remanufactured heads are a crapshoot. If we swap an engine, they cover a labor claim for us to replace it again if necessary.
I did used to work somewhere where the MO was repair, not replace. We always lost money on engine work. When I left that place, I came back a couple weeks later to collect my things and they had a Subaru engine on the bench. That is, three Subaru engines. They'd bought two core engines and were trying to piece together enough parts to make one good one. I opined that they could get a new shortblock and new heads from Subaru for less money than they spent on core engines and there would be no screwing around, no guess work, no potential comeback.
The only internal engine work I have done in the past six years was a few sets of rings in Honda V6s. There's no failures to worry about coming to bite you, you just pop it apart, replace the old rings with the new updated parts, and pop it back together. Not like, say, the Ecoboost 2.3 we replaced last month, where the grille shutters in the Explorer failed and they drove it on the highway until the engine locked up. Then let it cool off and kept going... there's going to be no user serviceable parts inside after that 
In reply to alfadriver :
I think we're saying the same thing. I guess what frustrates me is the "kids today" mentality . There will always be A grade techs who can do any work given to them with the proper resources. Age has nothing to do with it.
I work in auto parts and have both locally and regionally for almost two decades now. I've met great techs and other ones. I worked at a really good shop that would swap a motor but wouldn't rebuild because it doesn't make economic sense to do so. Was there techs there who could do it (and at least one who built his own race car engines ) yes. But that was for fun, and those guys were coming to work to get paid.
In reply to 1SlowVW :
I'm also frustrated with the generational whining. I worked with plenty of people who were just starting working as I was ending, and they were all super hard working and motivated to make a difference. But people have to realize that the situation decides what skills people need to know.
And I'm pretty sure the guy who learned how to rebuild a 70's era engine has to almost do it all over again for today's motors- with how rods are designed, how cams are put together, how fasteners are now being used. Let alone engines are not really even designed to be rebuilt, since they already have to last for emissions to 150k miles, meaning that well taken care of, they will last well past the nominal life of the rest of the car. Heck, my NB motor is just fine execpt for the PCV clogging up an blowing the valve cover gasket. And it's now 25 years old with +200k miles on it. Light years better than the Alfa sitting next to it. For an engine originally made in the '80s.
All of the things said point to an advantage to owning an older Miata; most of the time, repairs are simple and easy enough to do yourself. I'm just getting older and lazier and don't feel like doing the shims myself. I know that I am being a slacker. If it wasn't 100 degrees in my garage right now, I would be more likely to do it.
I do appreciate all of the feedback. The nice thing about the Miata community is the vast storehouse of knowledge that is out there.
1SlowVW said:In reply to alfadriver :
I think we're saying the same thing. I guess what frustrates me is the "kids today" mentality . There will always be A grade techs who can do any work given to them with the proper resources. Age has nothing to do with it.
I work in auto parts and have both locally and regionally for almost two decades now. I've met great techs and other ones. I worked at a really good shop that would swap a motor but wouldn't rebuild because it doesn't make economic sense to do so. Was there techs there who could do it (and at least one who built his own race car engines ) yes. But that was for fun, and those guys were coming to work to get paid.
OMG it is very much NOT a "kids today" thing, a lot of it is the old farts who won't touch anything laborious. Some of it is experience in getting burned on, say, putting new valves in a GM 3.6 that ate some timing chains, then finding out that the engine doesn't have enough oil pressure at idle for the VVT to work because the cam journals are too worn because the engine had a life of living 3-4 quarts low on oil. As an example from working at the place where we repaired and didn't replace.
But some of it is old habits. You see a lot of old guys on iATN whose mantra is don't bother even replacing leaky gaskets on an engine over 150k, just put an engine in it. On engines from the 80s that were really 1950s engines, this was not bad advice, but most modern engines have a lot more life in them than that. Like the common "LS" engine low oil pressure over 200k miles because the oil pickup O ring shrinks. I have replaced the oil pan gasket and pickup o-ring and seen the engines keep soldiering on for another 100-150k and then the truck rots out, the old guys would say there's no life left and it's not worth an oil pan gasket. And a lot of these guys are in places like Texas and Arizona where cars and trucks are basically immortal!
Modern engines are generally pretty good and will often go a long time without any internal problems. Electronics and peripherals seem to be the things that need fixing more often. Do electric motors even wear out? Maybe not. So, that's the game. The guys that work in auto shops work on what needs working on.
I do often wonder what the longevity will be for many of the current turbo motors. If the internals are built with the correct alloys, they should be durable, I suppose, but I wonder if people will be rebuilding them in 25 years.
In reply to Brett Tower :
In 25 years the parts to rebuild them may not be available.
Modern engine manufacturing techniques also tend to preclude rebuilding. Coated aluminum bores can't be bored or honed, etched aluminum bores (just like a Vega!) can't be bored or honed, etched aluminum valve guides, etc. If you have an engine with iron or steel liners, they may not be large enough to take an overbore. A Toyota 1ZZ that doesn't burn oil over 80k miles is a rare bird, because the bores wear and the valve guides wear and there's little you can do about it. (Change your oil more often! Acids in the oil eat the bores)
Cracked sintered connecting rods last well in service, and there are ways to rebuild them now with oversize rod bearings (you can't trim the mating faces and then hone then back to spec, because of the cracked faces) BUT a lot of the old farts see new ideas = bad and just throw them out even if they measure okay.
The largest issues seem to be proprietary control modules that may or may not be repairable. My Volvo is currently in need of a suspension control module, and the HVAC module is getting dodgy. Used are a crapshoot and people aren't rebuilding/repairing them.
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