Help!! My Intake Valves Keep Wearing Out! - Page 4 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Race Prep Miata race-only chat.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 01-10-2015, 04:00 PM   #61
Senior Member
iTrader: (6)
 
Join Date: Jun 2010
Location: San Rafael, CA
Posts: 1,083
Total Cats: 35
Default

Quote:
Originally Posted by hornetball View Post
I'm confused about your statement re: factory shims. I was always under the impression that you shim as required to achieve a seat pressure (which is what I think BogusSVO was showing). Shims are shims. Is there something special about the OEM shims? Or are you saying to make darn sure it is checked and adjusted as needed? I can see how a machine shop would be tempted to skip this step on a vanilla rebuild.
I should have been clearer with my previous statement. Supertech advertized spring rates are achieved using the factory shims. Without them spring rates are lower.

By measuring and shimming to your own spec you can use whatever shim(s) you need to.
k24madness is offline   Reply With Quote
Old 01-10-2015, 05:17 PM   #62
Elite Member
Thread Starter
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 5,981
Total Cats: 576
Default

Gotcha'. Thanks.
hornetball is offline   Reply With Quote
Old 01-10-2015, 05:44 PM   #63
Junior Member
 
Join Date: Aug 2010
Location: Texas
Posts: 162
Total Cats: 11
Default

I'm going to ask a stupid question. I thought the BP5A cam was a stock cam in most of the world and a drop in replacement here in the USA. Why do you need more spring than the factory springs?

robert
robertcope is offline   Reply With Quote
Old 01-10-2015, 05:49 PM   #64
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,925
Total Cats: 1,437
Default

Quote:
Originally Posted by robertcope View Post
I'm going to ask a stupid question. I thought the BP5A cam was a stock cam in most of the world and a drop in replacement here in the USA. Why do you need more spring than the factory springs?

robert
Pretty sure more spring = more revs
aidandj is offline   Reply With Quote
Old 01-10-2015, 05:52 PM   #65
Junior Member
 
Join Date: Aug 2010
Location: Texas
Posts: 162
Total Cats: 11
Default

Quote:
Originally Posted by aidandj View Post
Pretty sure more spring = more revs
"With the MS, Soft Cut (reduced timing to 10*BTDC) is 7000RPM and Hard Cut (Fuel) is 7200RPM." Yes, if he was turning more RPMs than stock, that would make sense, but he isn't.

robert
robertcope is offline   Reply With Quote
Old 01-10-2015, 09:15 PM   #66
Elite Member
iTrader: (2)
 
Join Date: Jun 2009
Location: Istanbul, Turkey
Posts: 2,038
Total Cats: 427
Default

Stupid question, sorry...

Factory shims.. Are we talking about these? (With an arrow next to it)





I mean, these are only 0.02" (0.5mm) thick.
How would such a tiny height reduction make a difference in spring rate?

Yes, I just found all 16 of these in a box of parts (I had received from the machine shop) left over from the time when I switched over to Supertechs. Guess they did not think they were necessary.
And, I had bigger fish to fry at the time, so I never checked...
Attached Thumbnails
Help!!  My Intake Valves Keep Wearing Out!-2ek7qj.jpg   Help!!  My Intake Valves Keep Wearing Out!-17g5fi.jpg  
Godless Commie is offline   Reply With Quote
Old 01-11-2015, 01:32 AM   #67
Senior Member
iTrader: (6)
 
Join Date: Jun 2010
Location: San Rafael, CA
Posts: 1,083
Total Cats: 35
Default

Yes godless commie those are suppose to stay. I forget the specs but kinda remember they are worth somewhere around 7lbs of seat pressure. I do remember they were a LOT more than I expected.
k24madness is offline   Reply With Quote
Old 01-11-2015, 04:58 AM   #68
Elite Member
Thread Starter
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 5,981
Total Cats: 576
Default

Quote:
Originally Posted by robertcope View Post
I'm going to ask a stupid question. I thought the BP5A cam was a stock cam in most of the world and a drop in replacement here in the USA. Why do you need more spring than the factory springs?

robert
You're not missing anything. I'm having some real problems with this "fresh" engine -- and I shouldn't be. We're just trying to figure it out. It did exactly the same thing on ST valves and springs that it did on the OEM valves and springs (in other words, the OEM wasn't any better or worse). I'm obviously not a happy camper.
hornetball is offline   Reply With Quote
Old 01-11-2015, 06:03 AM   #69
Senior Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Sweden
Posts: 1,387
Total Cats: 58
Default

Quote:
Originally Posted by Godless Commie View Post
I mean, these are only 0.02" (0.5mm) thick.
How would such a tiny height reduction make a difference in spring rate?
The spring rate is the same but the shims adjust the seat pressure (call it spring pre-load if you want).
NiklasFalk is offline   Reply With Quote
Old 01-11-2015, 02:23 PM   #70
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,212
Total Cats: 1,229
Default

Quote:
Originally Posted by Godless Commie View Post
I mean, these are only 0.02" (0.5mm) thick.
How would such a tiny height reduction make a difference in spring rate?
Pretty simple - the spring rate on ST Singles is ~9.4lb/mm. 0.020" shim means seat pressure should rise by ~4.7lbs.
Savington is offline   Reply With Quote
Old 01-11-2015, 07:23 PM   #71
Elite Member
iTrader: (2)
 
Join Date: Jun 2009
Location: Istanbul, Turkey
Posts: 2,038
Total Cats: 427
Default

Gents, I just pulled the head and posted some pics and videos on the other thread:

https://www.miataturbo.net/engine-pe...en-warm-82232/
Godless Commie is offline   Reply With Quote
Old 01-12-2015, 08:05 AM   #72
Senior Member
iTrader: (1)
 
Join Date: Jan 2011
Location: Chattanooga, Tn
Posts: 1,027
Total Cats: 153
Default

No shim

[/URL]

Shim

[/URL]
Attached Thumbnails
Help!!  My Intake Valves Keep Wearing Out!-2015-01-12%252007.55.56_zpsnk21qbaj.jpg  
TNTUBA is offline   Reply With Quote
Old 01-12-2015, 09:16 AM   #73
Elite Member
iTrader: (2)
 
Join Date: Jun 2009
Location: Istanbul, Turkey
Posts: 2,038
Total Cats: 427
Default

Quote:
Originally Posted by k24madness View Post
Yes godless commie those are suppose to stay. I forget the specs but kinda remember they are worth somewhere around 7lbs of seat pressure. I do remember they were a LOT more than I expected.
Quote:
Originally Posted by NiklasFalk View Post
The spring rate is the same but the shims adjust the seat pressure (call it spring pre-load if you want).
Quote:
Originally Posted by Savington View Post
Pretty simple - the spring rate on ST Singles is ~9.4lb/mm. 0.020" shim means seat pressure should rise by ~4.7lbs.
Quote:
Originally Posted by TNTUBA View Post
No shim

[/URL]

Shim

[/URL]
Thank you guys.
I really did not know this.
You live and learn, I guess.
Godless Commie is offline   Reply With Quote
Old 01-12-2015, 11:54 AM   #74
Elite Member
Thread Starter
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 5,981
Total Cats: 576
Default

Something else to keep in mind, the stiffer the springs, the more force you add with the shims. It's a linear relationship. So, adding that shim to ST light doubles has more effect than on ST singles which, in turn, has more effect than on stock springs.

And I can tell you that the shims were left out on my September head rebuild.
hornetball is offline   Reply With Quote
Old 01-12-2015, 12:15 PM   #75
Senior Member
iTrader: (6)
 
Join Date: Jun 2010
Location: San Rafael, CA
Posts: 1,083
Total Cats: 35
Default

Quote:
Originally Posted by hornetball View Post
Something else to keep in mind, the stiffer the springs, the more force you add with the shims. It's a linear relationship. So, adding that shim to ST light doubles has more effect than on ST singles which, in turn, has more effect than on stock springs.

And I can tell you that the shims were left out on my September head rebuild.
Bingo. That's why on my "supertech heavy doubles" the effect was 7lbs+, IIRC it was closer to 9lbs.

Now onto the next question. What spring pressure should you run with a BP5A cam?
k24madness is offline   Reply With Quote
Old 01-18-2015, 09:34 PM   #76
Goin Innnnn!!!
iTrader: (7)
 
Chooofoojoo's Avatar
 
Join Date: May 2014
Location: Denver, Co.
Posts: 460
Total Cats: 40
Default

Machine shop pulled my head apart today. ST singles without OE valve shims.

Curious along with K24madness as to what is the recommended Valve seat pressure for BP5a cam, and does anyone have the part number or place to acquire a set of OE shims?

(If anyone has a set laying around PM me!)

Last edited by Chooofoojoo; 01-18-2015 at 10:07 PM.
Chooofoojoo is offline   Reply With Quote
Old 05-23-2015, 02:20 PM   #77
Junior Member
 
Join Date: May 2008
Location: Grants Pass, OR.
Posts: 449
Total Cats: 14
Default

Is there a current discussion on this issue on a different thread as I am interested in what people have found out now that it is 4 months later. I am fixing to install some 1+ overs and was thinking about just using the inconel exhaust with OEM intakes. I would like to also use the 1+ intakes if the suggestions above fixed the problem.
jmann is offline   Reply With Quote
Old 05-23-2015, 02:30 PM   #78
Goin Innnnn!!!
iTrader: (7)
 
Chooofoojoo's Avatar
 
Join Date: May 2014
Location: Denver, Co.
Posts: 460
Total Cats: 40
Default

I ended up going +1mm intake and exhaust, but Manley not Supertech. Supertech light double springs, stock shim over bucket, bp5a intake, stock exhaust cam. Will be a zippy N/A motor for now, eventual TSE turbo. Motor is being swapped this week. Will report on findings over next few months.
Chooofoojoo is offline   Reply With Quote
Old 05-23-2015, 03:52 PM   #79
Elite Member
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,658
Total Cats: 235
Default

Quote:
Originally Posted by jmann View Post
Is there a current discussion on this issue on a different thread as I am interested in what people have found out now that it is 4 months later. I am fixing to install some 1+ overs and was thinking about just using the inconel exhaust with OEM intakes. I would like to also use the 1+ intakes if the suggestions above fixed the problem.
I run supertech undercut coated stock size intake valves, +1 inconel exhaust valves. I cut the seats myself, did a 5 angle on the intakes, 4 on the exhaust, kept the seat widths conservative. Stock shims/buckets, I just tipped the valves to adjust the clearances.

I run heavy double ST valve springs without the shims (opps). Reved the engine to 8,800 about 200 times, put about 2,000 miles on it. Broke a piston 3 weeks ago and checked the head, valves all seal perfect.

My guess is if you're vavles are tightening up, it's due to a machining error. Something is wearing in causing the clearances to tighten.
patsmx5 is online now   Reply With Quote
Old 05-23-2015, 09:44 PM   #80
Junior Member
 
Join Date: Jan 2015
Posts: 272
Total Cats: -22
Default

Any chance you guys are wearing out the valve guides and that is allowing the valve to move around a bit on the seat? This happened to me years ago on a honda engine.
Alternative is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 04:11 PM
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 03:00 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 11:04 AM
Moroso Air Oil Separator Catch Can Aroundcorner Miata parts for sale/trade 2 10-01-2015 03:20 PM
Going back to stock. Need some 1.6 parts. Trent WTB 2 10-01-2015 12:15 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 12:05 PM.