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Old 08-21-2014, 02:18 PM   #1
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Default Stronger Valve springs with stock valves for RACE!!

This have come to mind after seeing recent talks about stock head and higher RPM. Now I have not done anything to the valves or the valve train. The head is definitely ported. An associate of mine that knows more than I will ever know about engine design and modified engines (he has been building funny car 5000hp+ engines since the 80's) recommended I don't go with bigger valves. But with that big turbo I am thinking I will need the higher RPM. Would you guys recommend changing the springs over?

The head is a 99 head, heavily ported and polished. I have an EFR 8374 and looking to run ALLOFIT race only. No street use. This thing will only see under 4000rpm when it is spinning tires out of the pits!

I know the stock valve-train will most likely be fine a few times at about 8000 rpm. But continuously pushing it at 550-600hp might not be the best idea. Do I go all out with springs or something in the middle?
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Old 08-22-2014, 11:23 PM   #2
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springs to help seal the valves with all that boost you'll be running. go big or go home!
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Old 08-23-2014, 12:22 AM   #3
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I would do stiffer valve springs. My 99 head had +1mm valves and here is the result of 14 psi and the motor's first track day. 70% cylinder leakage is acceptable right?

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Old 08-23-2014, 02:06 AM   #4
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The springs collapsed???
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Old 08-23-2014, 02:21 AM   #5
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Yeah. I'm not sure what I'm seeing in the pic, other than a mess. Is that oil or water?
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Old 08-23-2014, 02:52 AM   #6
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hammered valves. the folks at supertech say valve float. how was the valve lash after that event.
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Old 08-23-2014, 11:39 AM   #7
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what are the chances of both valves having been hammered? What RPM? Of course you can replicate that at 8,500. Just curious? I do not over-rev my engine. I have been racing for over 10 years and never have and not planning to do it!
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Old 08-25-2014, 09:39 PM   #8
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This has been discussed. Dual valve springs & subs recommended. Emilio has posted numerous times what is required for 8k+ rpm and will sell you the parts.
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Old 08-26-2014, 10:01 AM   #9
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How much are the SUBs worth. I'm going to be checking my valve clearances this off season and installing the inner springs to my supertech duals. And if I need the change the shimming on more than a couple valves I might as well just get the SUBs. I've been spinning to 8.5k with just the outer springs of the supertech duals on the VVT head. If I can turn that up another few rpms I gain another mph for every ~125rpms and I've been hitting the limiter a few times lately while still down 200hp from the competition.
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Old 08-26-2014, 11:34 AM   #10
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why not shimless lifters?
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Old 08-27-2014, 11:18 PM   #11
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Quote:
Originally Posted by bcrx7 View Post
what are the chances of both valves having been hammered? What RPM? Of course you can replicate that at 8,500. Just curious? I do not over-rev my engine. I have been racing for over 10 years and never have and not planning to do it!
This happened to every single one of my intake valves. Rev limiter was set to 7K with no over revs. No idea on what the initial lash was since it was built by a reputable shop.
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Old 08-28-2014, 01:42 AM   #12
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what kind of valves? im starting to think supertech valves are junk.
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Old 08-28-2014, 02:06 AM   #13
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Quote:
Originally Posted by cjsafski View Post
This happened to every single one of my intake valves. Rev limiter was set to 7K with no over revs. No idea on what the initial lash was since it was built by a reputable shop.
Good to know! I guess I am shopping for springs!
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Old 08-28-2014, 09:28 AM   #14
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Quote:
Originally Posted by iantboyd View Post
why not shimless lifters?
That would be ideal IF it exist for the B engine- does it.

If not, shim-under-bucket is. It's a significant reduction in valve load, reduces wear and improves action.

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Old 08-28-2014, 10:32 AM   #15
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Quote:
Originally Posted by m2cupcar View Post
That would be ideal IF it exist for the B engine- does it.
Ford Zetec also use 30mm lifters.
https://www.miataturbo.net/build-thr...2/#post1068251
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Old 08-28-2014, 10:37 AM   #16
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shimless lifters sound expensive since you have to buy new lifters to adjust clearance.

It looks like the zetec are 32.6g for 17.35mm height while the supertech subs are 34.2g + shim weight.
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