Retain stock shims under Supertech doubles?
#1
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I recently purchased valve springs from 949 Racing. My installer is questioning whether to leave the stock shim under the springs of my Supertech light doubles. I thought that I understood that it was to remain but he is questioning the need since the Supertechs come with their own perch.
Guidance, please!
I know others will be buying them soon after the recent discussion about boost pressure reducing the closing force applied by the springs on the intake valves.
Guidance, please!
I know others will be buying them soon after the recent discussion about boost pressure reducing the closing force applied by the springs on the intake valves.
#3
If your installer is a machine shop, he probably has a machine to measure seat pressure. Basically it looks like an arbor press, but has a dial indicator and a gauge that reads lb force of pressure. So you measure and the installed height on a miata between the retainer and bottom of head where the spring lands is say X, he compresses the spring to X length and can tell you seat pressure at that height. Then compress to coil bind, and now you have Y amount of compression before coil bind. And also compress say 8.9mm (whatever max lift is of your cam) and tell you seat pressure at full compression, and you'll know how close to coil bind you are there too. Then no guessing, you know if you can or can not run that shim, based on measured pressures you'll know if you want them.
I left them on my head, I run the super tech heavy doubles.
You got a link to recent discussion you mentioned? I must have missed it. But yes, 2 motors ago I lost an engine likely due to not enough seat pressure, turbine pressure keeping exhaust valves from seating.
I left them on my head, I run the super tech heavy doubles.
You got a link to recent discussion you mentioned? I must have missed it. But yes, 2 motors ago I lost an engine likely due to not enough seat pressure, turbine pressure keeping exhaust valves from seating.
#5
Spoonfeeding activated
https://www.miataturbo.net/race-prep...ing-out-82462/
Read post 58 and on.
It seems that the ST springs were designed to be used with the stock shims.
https://www.miataturbo.net/race-prep...ing-out-82462/
Read post 58 and on.
It seems that the ST springs were designed to be used with the stock shims.
#6
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Thanks, guys. I heard from Emilio directly and also just received a reply email back from Supertech from this morning. They are required. Apparently there were also supposed to be instructions in my box but it had been opened previously and they were missing. FML.
For guys who are considering this, it is possible to upgrade the valve springs with the head still on the block. My mechanic is using a rope to hold the valve up while swapping springs. Pretty neat.
For guys who are considering this, it is possible to upgrade the valve springs with the head still on the block. My mechanic is using a rope to hold the valve up while swapping springs. Pretty neat.
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