Valves too long. What can I do?
#1
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Valves too long. What can I do?
A few months ago I dropped my '99 head off at a machine shop. The valves on cylinder 1 had collided with the piston, after the rod had let go.
So I bought a set of new Supertech +1mm valves and springs from another member here. The machine shop took ages to do the job and then at first they didn't realize the valves were 1mm bigger. I explained everything when I dropped off the head. So after they've done all the work for stock sized valves they were going to install the valves and realized it doesn't work.
I finally got the head back with everything installed and guess what? There is no valve lash, because the Supertechs are 0.6mm longer. I'd told them that too when I dropped off the head.
I have given them the opportunity to fix the problem, but at this point, I'd rather do it myself.
Here are my options:
- Take it all apart and grind down the valve stems (for that I need a machine shop which will take months again)
- Install shorter shims (expensive - a shim is almost $4 and I need 16 of them. Also I can't tell right away, what size I need, since I have 0 lash right now, so I would need to buy a complete set with different sizes!)
- OR: I have a set of hydraulic lifters off a '97 engine. Can I install those? Does the '99 head have what it takes to feed them with oil?
BTW: Emilio from 949 said in an email to me that the longer valves will work with the stock cams.
I'm only planning on running the engine like that for maybe 6-12 months, so it needn't be the super-best solution, just something to work for a while.
So I bought a set of new Supertech +1mm valves and springs from another member here. The machine shop took ages to do the job and then at first they didn't realize the valves were 1mm bigger. I explained everything when I dropped off the head. So after they've done all the work for stock sized valves they were going to install the valves and realized it doesn't work.
I finally got the head back with everything installed and guess what? There is no valve lash, because the Supertechs are 0.6mm longer. I'd told them that too when I dropped off the head.
I have given them the opportunity to fix the problem, but at this point, I'd rather do it myself.
Here are my options:
- Take it all apart and grind down the valve stems (for that I need a machine shop which will take months again)
- Install shorter shims (expensive - a shim is almost $4 and I need 16 of them. Also I can't tell right away, what size I need, since I have 0 lash right now, so I would need to buy a complete set with different sizes!)
- OR: I have a set of hydraulic lifters off a '97 engine. Can I install those? Does the '99 head have what it takes to feed them with oil?
BTW: Emilio from 949 said in an email to me that the longer valves will work with the stock cams.
I'm only planning on running the engine like that for maybe 6-12 months, so it needn't be the super-best solution, just something to work for a while.
#4
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Yeah - they machined the seats. I don't think they're cut too deep. I saw the head with just the valves in and they looked nice and flush.
But the Supertech valves are 0.6mm longer. If you don't adjust for that somehow, you're not going to get the valves to seat!
Savington: From a purely theoretical standpoint wouldn't it be better to go with thinner shims instead? That would keep the valvetrain weight down. If I can't do the quick & easy fix (hydraulic lifters), then i would like to do what's best for performance, if it's not too expensive.
But the Supertech valves are 0.6mm longer. If you don't adjust for that somehow, you're not going to get the valves to seat!
Savington: From a purely theoretical standpoint wouldn't it be better to go with thinner shims instead? That would keep the valvetrain weight down. If I can't do the quick & easy fix (hydraulic lifters), then i would like to do what's best for performance, if it's not too expensive.
#5
Supertech Cam Follower Lifter Miata
Supertech Lash Caps Miata
Probably to expensive, but its what I did.
Supertech Lash Caps Miata
Probably to expensive, but its what I did.
#6
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^ Yupp. That's a little more than I can afford to spend right now.
Just the lash caps are more expensive than the stock shims anyway. And I'd still have the problem of not knowing what size I'd need.
Just the lash caps are more expensive than the stock shims anyway. And I'd still have the problem of not knowing what size I'd need.
#10
Supertech Cam Follower Lifter Miata
Supertech Lash Caps Miata
Probably to expensive, but its what I did.
Supertech Lash Caps Miata
Probably to expensive, but its what I did.
Yet another; Zetec Shimless (Ford YS4Z-6500-...), if the needed thickness is in the range 17.145-17.655mm.
#11
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I'm far from a valvetrain guru, however it's been my experiance (on other engines such as the ACVW) that cam manufacturers seem to specify different cam grinds for use with hydraulic vs. solid lifters, insofar as that they use slightly different lobe profiles for the two.
I've utterly no idea what, if any, practical ramifications this might have in the real world of B engines.
I've utterly no idea what, if any, practical ramifications this might have in the real world of B engines.
#12
I'm far from a valvetrain guru, however it's been my experiance (on other engines such as the ACVW) that cam manufacturers seem to specify different cam grinds for use with hydraulic vs. solid lifters, insofar as that they use slightly different lobe profiles for the two.
I don't know if there are oil feeds for the HLAs in the NB heads (position, volume etc). Looking at some old post by FM-Keith, it seems like the VVT head lacks the feed but the earlier NBs have it.
#13
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HLA cams don't have to have a initial ramp to take out the lash, they can stomp directly to the real ramp without damaging the valvetrain.
I don't know if there are oil feeds for the HLAs in the NB heads (position, volume etc). Looking at some old post by FM-Keith, it seems like the VVT head lacks the feed but the earlier NBs have it.
I don't know if there are oil feeds for the HLAs in the NB heads (position, volume etc). Looking at some old post by FM-Keith, it seems like the VVT head lacks the feed but the earlier NBs have it.
#14
no go on the HLA's as the 99 cams are ground for soild lifters.
in this situation, get the valves ground down.
i have to say that supertech did a dick move by making the valves .6 longer in the stem and not above the keepers.
find a different machine shop to do the work in a timely manner. its simple basic work that doesnt even take that long.
in this situation, get the valves ground down.
i have to say that supertech did a dick move by making the valves .6 longer in the stem and not above the keepers.
find a different machine shop to do the work in a timely manner. its simple basic work that doesnt even take that long.
#17
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The issue you're going to have is that 0.6mm is ~.024". Most Miata OEM shims are in the .125-.132 range, so even if the seat cut didn't lose you any distance at all (it did), the 0.6mm longer valves are going to put you outside of the usable range of any available shimset, and probably outside the safe range for the factory HLAs too.
You really need to find a competent machinist to finish the job. Give him all the lifters and he should be able to get everything set up correctly. It's the only correct way to do this.
You really need to find a competent machinist to finish the job. Give him all the lifters and he should be able to get everything set up correctly. It's the only correct way to do this.
#18
If the valves are sitting flush to the chamber that means the machine shop sunk the valves. This kills flow, screws with valve spring install height/seat pressure and lash etc. I suggest you correct the real problem and take it to a competent machinist, you may need to have new valve seats installed.
#20
Tour de Franzia
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Find a machinist who knows more than me, which is sad. You need to call it a loss and move on because this engine will not live a happy life. Think of all the time and money you're going to continue putting in and around the engine, when it will certainly puke it's guts through your turbonator.