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Old 02-11-2008, 04:21 PM   #1
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Default R&D thread for shim-under-bucket conversion!

OK I know Mazda Comp sells this but I want other options. Because. Ok because i'm not a member. fine.

Anyone (Brian you have my head... got calipers?) know the OD and length of the buckets?

The valve stems are 5.96mm for intake or 5.94 for exhaust. Supertech sells a 6mm lash cap which I assume will work.

I remember hearing rumors that the 4AGE buckets were the right size, but rumors aren't guaranteed to open valves.

Here's the part info:
Code:
Application                       Part Number   Diameter    Length      Pad Thickness / Post            Weight

Toyota 4AGE 16v                   CF-28/3.85+    28mm        23mm        3.85mm + Shim 1.45-3.20mm      26.3 grs
Toyota / Nissan RB26              CF-31/2.7      31mm        24.8mm      2.7mm                          28.6 grs
Toyota / Nissan                   CF-31/3.78     31mm        25.5mm      3.78mm                         30.9 grs
Toyota / Nissan / Mazda Duratec   CF-31/2.5+     31mm        25.5mm      2.5mm + Shim 1.45- 3.20mm      29.5 grs
Toyota 2JZ/3SGTE/1ZZ/Scion/       CF-31/3.28+    31mm        25.5mm      3.28mm + Shim 1.45-3.20mm      31 grs
      Tacoma 2RZ-3RZ/Nissan RB26
Opel/Peugeot oversize             CF-32.5/2.5    32.50mm     23.1mm      2.54mm                         26.3
BMW                               CF-33/ 14      33mm        26mm        14mm                           33 grs
BMW                               CF-33/2.9      33mm        26mm        2.92mm                         33 grs
BMW                               CF-33/3.0      33mm        26mm        3.0mm                          33.2 grs
Nissan / Subaru H6 (1st Gen)      CF-34/2.5+     34mm        26mm        2.5mm + Shim 1.45- 3.20mm      32.4 grs
Nissan KA24                       CF34/3.5+      34mm        26mm        3.5mm + Shim 1.45- 3.20mm      33.5 grs
Nissan 350Z/ VQ35                 CF34/6.5+      34mm        21mm        6.5mm + Shim 1.45-3.20mm       34 grs
VW / Subaru                       CF-35/2.8      35mm        26mm        2.8mm                          36.5 grs
VW / Subaru / Sierra Cosworth     CF-35/3.3      35mm        26mm        3.3mm                          36.6 grs
VW / Subaru EJ20-EJ25             CF-35/ 2.7+    35mm        25mm        2.7mm + Shim 1.45- 3.20mm      35.2
VW / Subaru EJ20-EJ25             CF-35/ 3.7+    35mm        25mm        3.7mm + Shim 1.45-3.20mm       38.2
BMW M12/ S14 (Long valve)  / VW   CF-37/3.3      37mm        26mm        3.3mm                          40 grs
BMW M12/ S14 (Long valve)  / VW   CF-37/3.6      37mm        26mm        3.68mm                         40.6 grs
BMW M12/ S14 (Long valve)  / VW   CF-37/3.9      37mm        26mm        3.90mm                         40.9 grs

Valve Lash Caps                     
LC-55 / LC-60 / LC-65         
5.5mm / 6mm   / 6.5mm
Several thicknesses  1.2 - 1.6 grs
one of those is bound to be our size. or close. or close enough

Also: at what point do the dual springs become necessary? The Supertech duals are about 50% more seat pressure (74lb) and about 30% higher rate overall.


notes:
Mazda Motorsports "solid lifter" p/n? B6N7-12-183
From a protege site the bucket p/n is: BP2Y-12-183
http://www.maruhamotors.co.jp/miata/...camfornb8.html


thanks guys.
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Old 02-11-2008, 05:17 PM   #2
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I guess I should put mine up for sale.
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Old 02-11-2008, 05:25 PM   #3
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I guess I should put mine up for sale.
errr, your what???
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Old 02-11-2008, 05:37 PM   #4
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No idea if this is relevant or not, but I ran across this post over an mnutter regarding potential interchange between Miata, Zetec, Duratec (MZR), and Honduh springs (and lifters).

http://forum.miata.net/vb/showpost.p...9&postcount=24

Scroll about halfway down the post for the details, including "graded" solid lifters that don't require shims.
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Old 02-11-2008, 06:27 PM   #5
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Any 6mm shims will work. I used a set of 16 off ebay made for a chevy. Cost $30 shipped.

You can get teh mazdaspeed lifters through MiataRoadster.com for only $200. For that price I wouldn't bother searching for other methods.

Glad to be of service.
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Old 02-11-2008, 06:36 PM   #6
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200? well sheeit.
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Old 02-11-2008, 09:30 PM   #7
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I've got an entire mazdacomp shim under bucket valve train from 99 cylinder head (springs and cams). They're stuff we ran in the motorola/grandam cup. I put them up on miatanet classifieds but got nothing but wieners.
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Old 02-11-2008, 09:32 PM   #8
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Rob--we were discussing your cams, but never really got to terms. If you have a price in mind for the whole set up, shoot it my way. Honestly, all my spare change is going to the block right now, but maybe...
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Old 02-11-2008, 09:34 PM   #9
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Quote:
Originally Posted by m2cupcar View Post
I've got an entire mazdacomp shim under bucket valve train from 99 cylinder head (springs and cams). They're stuff we ran in the motorola/grandam cup. I put them up on miatanet classifieds but got nothing but wieners.
I'd assume that setup is too hard core for a street car?
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Old 02-11-2008, 09:38 PM   #10
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Quote:
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I'd assume that setup is too hard core for a street car?
Randy Stocker was telling me it would be pretty bad *** for a boosted street car actually.
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Old 02-11-2008, 11:02 PM   #11
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brian (neogensis "i've awaken the beast") has a good description of what it's like trying to get cams like this to idle - a lot can be tuned out, tho still lumpy compared to a stock cam. BUT with a turbo car and reduced overlap it shouldn't be as bad. I never ran these on the street, but on the track way up in the rpm they were just badass.

Without the cams, the valvetrain would be fine IMO. It's far lighter than the stock setup and will spin way easier.

Sorry about that Ben - totally forgot. I'll hang on to that stuff for your engine, just totally spaced.
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Old 02-11-2008, 11:50 PM   #12
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i already sent the money to billwilner for the buckets. just need to find brian-neo's source for the cheap lash caps.

Brian, did you get all one size or custom sizes to fit your specific application?
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Old 02-12-2008, 08:04 AM   #13
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I had to grind them manually to fit. I used a diamond coated knife sharpened. Takes forever but its worth it. Just search ebay for 6mm caps.
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Old 02-12-2008, 11:18 AM   #14
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^Totally gonna show my *** here. I understand how shim under bucket works... but exactly what is the advantage over the current configuration of the valvetrain. What is this gonna buy you? What is the advantage?
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Old 02-12-2008, 11:25 AM   #15
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I can deal with grinding my own caps I guess... I've got the sharpeners

Sam, the benefits are mostly reduced weight and the ability to run higher lift cams with less liklihood of destruction...

Normal shims are big quarter-sized things that are kinda heavy compared to the pea-sized lash caps used with shim-under-bucket. Plus at high rpm with big cams, if you float the valves, those standard shims are no longer captured by anything and can slip out from under the valves and do bad things.

but mostly the lower reciprocating mass means the valvetrain can handle higher speeds.
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Old 02-12-2008, 11:28 AM   #16
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Quote:
Originally Posted by samnavy View Post
^Totally gonna show my *** here. I understand how shim under bucket works... but exactly what is the advantage over the current configuration of the valvetrain. What is this gonna buy you? What is the advantage?
You dont risk spitting the tiddly-wing stock shims at high RPM, wich could damage the head. Its also lighter, which is a big deal at those RPM's.
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Old 02-12-2008, 11:51 AM   #17
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What does this type of benefit does this modification produce, sorry to hi jack.
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Old 02-12-2008, 11:59 AM   #18
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Quote:
Originally Posted by Saml01 View Post
What does this type of benefit does this modification produce, sorry to hi jack.

.
Quote:
Originally Posted by y8s View Post
Sam, the benefits are mostly reduced weight and the ability to run higher lift cams with less liklihood of destruction...

Normal shims are big quarter-sized things that are kinda heavy compared to the pea-sized lash caps used with shim-under-bucket. Plus at high rpm with big cams, if you float the valves, those standard shims are no longer captured by anything and can slip out from under the valves and do bad things.

but mostly the lower reciprocating mass means the valvetrain can handle higher speeds.
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Old 02-12-2008, 12:50 PM   #19
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and less mass means you don't need stiff springs: less spring rate = less pressure on the cam lobes and less effort to rotate the cams
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Old 02-12-2008, 02:20 PM   #20
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Quote:
Originally Posted by m2cupcar View Post
and less mass means you don't need stiff springs: less spring rate = less pressure on the cam lobes and less effort to rotate the cams


so would stock springs handle a .400 lift cam at 8500 rpm or is that just silly...
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