Welcome to the North American Subaru Impreza Owners Club Wednesday July 30, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Built Motor Discussion

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 08-10-2007, 04:25 AM   #1
sick1.8t
Scooby Specialist
 
Member#: 22345
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Boston
Vehicle:
2003 RSX
black

Default Shim over bucket vs. Shimless bucket question.

i'm using 02 wrx and an sti block to build a hybrid motor.
i'l like to not have to buy $300 worth of shimless buckets just to get a little higher redline, but i guess i will if i have to.
the heads setup will have stage 2 cams.

My questions:
how many more rpms will swapping to shimless gain me?
how much of that effect is from weight and how much is from the 1 piece design?
are most shim/buckets replaced when different cams are installed anyway?

also, what about making the 2 piece shim over bucket design into a 1 piece?
i'm a machinist, so there may be a way to secure the shim with a strong epoxy or possibly even a couple tiny set screws. this would stop the shims from spitting out, but it wouldnt save any weight. hence the above quesion.

lastly, heres my proposed setup, commentary welcome :-)

to be determined stage 2 cams
brian crower valve springs and Ti retainers
shimless buckets?
lightly ported ej20 heads
cometic copper heagasket for proper CR
stock 05 sti shortblock
05 N/A sohc intake manifold
3/8" phenolic spacer
possibly converting the stock fuel rail to a parallel setup
FMIC
tubular headers and up pipe
stock td04 and DP to 3" cat back till i save up for a gt30
* Registered users of the site do not see these ads.
sick1.8t is offline   Reply With Quote
Old 08-10-2007, 11:32 AM   #2
Acostafan
Scooby Specialist
 
Member#: 67398
Join Date: Aug 2004
Chapter/Region: South East
Location: Chattanooga, TN
Vehicle:
2002 Now with 100%
RDA of 2.5l Goodness!!!

Default

I would think with that setup you'd be able to do 8Krpm but of bigger concern is, even with the light port on the heads, it might be better for you to just get a set of STI heads instead. Don't know about the shortblock either with respect to rev limits. What you want to do WILL work well, but if you plan on making bigger power, the WRX heads will only flow so much. Shimless buckets are nice, but spitting shims is relatively rare. I saw the rev limiter A LOT in my WRX, and never had a problem. Shims and buckets all in good shape when I tore it down to do my hybrid build. Yes, you will want to check and set valve lash after you put new cams in. I would in NO WAY try to secure the shims with epoxy or set screws. It's just a bad idea. As I said, spitting shims is rare but if you want a higher rev limit and more power, shimless are a necessity. Hope this helps some.
Acostafan is offline   Reply With Quote
Old 08-10-2007, 01:08 PM   #3
sick1.8t
Scooby Specialist
 
Member#: 22345
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Boston
Vehicle:
2003 RSX
black

Default

thanks.
anyone know how many rpms are usually gained by going to shimless, and if that is because of the 1 piece design or because of the weight?
also anyone know what the rev limit of the 05 sti block is?
sick1.8t is offline   Reply With Quote
Old 08-10-2007, 01:42 PM   #4
p1prodrive
Scooby Newbie
 
Member#: 149827
Join Date: May 2007
Location: united kingdom
Vehicle:
2000 600 bhp p1
sonic blue

Default

please explain 'valve lash' ??
p1prodrive is offline   Reply With Quote
Old 08-10-2007, 02:53 PM   #5
MY99 2.5GT
Scooby Specialist
 
Member#: 5030
Join Date: Mar 2001
Chapter/Region: MAIC
Location: Martinsburg, WV, USA
Vehicle:
1999 Legacy 2.5GT
05 Legacy GT 06 Armada

Default

Valve lash is the space between the top of the bucket and the lowest point on the cam lobe. There is a tolerance in the thousandths for this opening.

Normally on a shim over bucket setup you would use wafer shims to increase/decrease this gap. On a shimless bucket you would have to order thicker/thinner buckets. On a shim under bucket setup you would use lash cap pills that sit on top of the valves but under the bucket.

Shimless is by far the best way to go but one of the most expensive. But you get what you pay for

As for how many more RPM's you could rev too. . .

I was told not to go above 7000 consistently with the stock shim over bucket setup with stock cams.

If you go with stage two cams and plan to rev beyond 7000 rpms then you should definitely convert to shimless and stiffer valve springs. Gruppe-S sells a kit for $999 that includes all 4 Helix 264 (equevilant to some other's stage II) but they also come with uprated springs with titanium retainers.

The shimless buckets will run you around $25 each.
MY99 2.5GT is offline   Reply With Quote
Old 08-10-2007, 07:57 PM   #6
sick1.8t
Scooby Specialist
 
Member#: 22345
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Boston
Vehicle:
2003 RSX
black

Default

i've got brian crower springs and Ti retainers already, i just havent figured out what cams i want.
i was doing some research on the 05 sti block and i think that i'm going to use a 7500 rpm limit on the setup. its only 500 more than the stock shim over bucket redline, but i'll have the cams on there too which may effect things.
sick1.8t is offline   Reply With Quote
Old 08-11-2007, 03:43 PM   #7
p1prodrive
Scooby Newbie
 
Member#: 149827
Join Date: May 2007
Location: united kingdom
Vehicle:
2000 600 bhp p1
sonic blue

Default

Quote:
Originally Posted by MY99 2.5GT View Post
Valve lash is the space between the top of the bucket and the lowest point on the cam lobe. There is a tolerance in the thousandths for this opening.

Normally on a shim over bucket setup you would use wafer shims to increase/decrease this gap. On a shimless bucket you would have to order thicker/thinner buckets. On a shim under bucket setup you would use lash cap pills that sit on top of the valves but under the bucket.

Shimless is by far the best way to go but one of the most expensive. But you get what you pay for

As for how many more RPM's you could rev too. . .

I was told not to go above 7000 consistently with the stock shim over bucket setup with stock cams.

If you go with stage two cams and plan to rev beyond 7000 rpms then you should definitely convert to shimless and stiffer valve springs. Gruppe-S sells a kit for $999 that includes all 4 Helix 264 (equevilant to some other's stage II) but they also come with uprated springs with titanium retainers.

The shimless buckets will run you around $25 each.
thank you that has cleared a few things up

matt
p1prodrive is offline   Reply With Quote
Old 08-15-2007, 01:57 AM   #8
FuJi K
Scooby Guru
 
Member#: 3687
Join Date: Jan 2001
Chapter/Region: MWSOC
Location: St. Paul, MN
Vehicle:
MY99 GF4 JDM 6spd
NF Performance

Default

You want to not just LIGHTLY port them but really PORT them if you're thinking of porting. If you're only LIGHTLY porting them, it's not worth porting them at all.

Here's my PORTED WRX head (bottem) w/ the 2.5L DOHC head (top).
FuJi K is offline   Reply With Quote
Old 09-03-2007, 10:29 PM   #9
edo2000
Scooby Specialist
 
Member#: 68709
Join Date: Aug 2004
Chapter/Region: AKIC
Location: Kenai Peninsula, AK
Vehicle:
2012 WRX
red

Default

To continue this topic:

With shimless buckets (which I have with my 2004 2.0L WRX), you need to buy new buckets to adjust valve lash?

I am planning to build a hybrid - 2.5L shortblock with low mileage WRX heads. I was planning to add Brian Crower 272 cams, using the stock valvetrain. With new cams, I assume I'll have valve lash adjusting to do.

I would love to take it to a subaru-aware machine shop, but I don't have one anywhere close to me, here in small-town Alaska.

Any tips or advice? Thanks.
edo2000 is offline   Reply With Quote
Old 09-03-2007, 11:33 PM   #10
charliew
Scooby Specialist
 
Member#: 125304
Join Date: Sep 2006
Location: Crawford, TX.
Default

sick1.8t, I'm no expert but when you look at the shim over bucket design it's a good design. When oil gets between the shim and the bucket there is quite a bit of surface tension between the two. Also take the mike and measure the lip that the shim sets in. It seems to be about .080 to me on a casual observation. This means you would have to have more valve float than that for one to get out of it's socket. The thickness of the shims varies from about .184 to .222 if I remember correctly. If you have that bad of valve float, thats not going to be the only problem. In the 80's I had a sb chev. that had worn valve guides and seals and a cheap fix was to buy a kit that came with covers that you glued on the valve retainer with a silicon glue that came with the buckets. Those have never come off, the're still on the motor. I'm sure for added insurance you could use a silicon and glue the shims on and when you need to change one you could just soak the bucket in some laquer thinner and it would release. If you're going to spin more rpms than stock you need better springs. Also if you change cams and go more rpms you need better springs. The one piece design is mainly for weight savings and somebody has probably already weighed the two different styles and can tell the difference in weight. If you need to go past 7500 rpms you better do some work to the oil system if you want reliability. Valve float is usually thought of to be when the cam is at the highest opening point, the valve keeps going farther but it can also be valve bounce at the seat when it comes down to seal I don't know if it would bounce far enough to let the shim come out but it might. Chev engine builders found that the new style beehive springs chev developed for the ls1 would give more power at rpms that they thought were ok with other springs, they saw no signs of float but just by changing the springs they found more power. These springs get smaller at the top and therefore use smaller retainers and are a lot lighter but also have better metalurgy for durability. I think it also has better frequency control. chev. needed this because the roller cam motors have a lot more mass to control at high rpms.

Anyway you probably can use shim over buckets. unless you improve the oiling of your motor to go more rpms than stock.

Charlie
charliew is offline   Reply With Quote
Old 09-04-2007, 12:38 AM   #11
ilivas
Scooby Specialist
 
Member#: 56056
Join Date: Feb 2004
Chapter/Region: South East
Location: Hickory, NC
Vehicle:
2004 wrx
T04R Turbo / 8k rpm 257

Default

wrong thread

Last edited by ilivas; 09-04-2007 at 12:51 AM.
ilivas is offline   Reply With Quote
Old 09-04-2007, 11:49 AM   #12
sick1.8t
Scooby Specialist
 
Member#: 22345
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Boston
Vehicle:
2003 RSX
black

Default

thanks charlie, i had been wondering about using a 2 part expoxy made for metal to secure the shim to the bucket. they make some epoxies that are rated at 2500lbs, which should be plenty. the only downside would be it will make the shim taller than it needs to be since the epoxy needs to be between the shim and the bucket. i'd just need to account for that.
sick1.8t is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Shimless Bucket vs Shim Over Bucket soobaviator Factory 2.0L Turbo Powertrain 8 04-24-2010 01:58 PM
Ej20k w/shim over bucket?? Cbgrandtheftauto Pre-2002 Factory Turbo Powertrain 8 03-10-2010 04:41 PM
Shimless bucket question... 2.5SR40WRX Built Motor Discussion 18 09-05-2007 09:57 PM
Shim over bucket to Shimless swap? haji Subaru Conversions 10 02-02-2006 01:08 AM
WRX Valve buckets Vs STi Buckets wRxbeater11 Factory 2.0L Turbo Powertrain 9 10-06-2004 12:37 PM


All times are GMT -4. The time now is 09:09 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.