Valves & Guides

[Gabs]

Hey guys,

You may or may not have read my previous post wondering if Supertech was a reputable company to buy from. Well after Wazzu informed me they are a well known and trusted company, I decided to use their products to rebuild my head.

So I have sitting here 8 Exhaust valves (BMEVN-1030s) and 8 Intake valves (BMIVN-1030s). Upon unboxing these the first thing I noticed was the stem diameter seemed smaller then the OEM Valves, I wasn't aware of this when ordering, shame on me for not asking enough questions. I went to the toolbox and grabbed the micrometer and sure enough these valves are 5.969mm stem diameter appose to the 6.959mm valves I removed.

I'm guessing these valves would be used with a 12.56 x 6mm valve guide then?
Like these: http://www.rmeuropean.com/Part-Number/Valve-Guide---IntakeExhaust-1st-Replacement-(1256-X-600-mm)-__11121735533_CAN_BA4EBA02.aspx

What is the purpose of using smaller valve stem diameter? I would Imagine maybe for gains is flow, but surely these would be very very minimal.

EDIT:
After doing a little research I now see the later E36 & Z4 M42/M44 seems to be using this valve stem diameter. Will I have any issue using these valves with the above guides? I'm pretty sure I wont but its always good to get a 2nd opinion.

[dsm2002]

I have the +1mm version of these valves in an E30 M42 head. I purchased Metric Mechanic 6mm valve guides as I could not find a BMW part number for the 6mm valve guide other than 11 12 1 735 534 which is discontinued. You should have no problems.

The advantage is reduced valve weight and better flow. Every little bit helps! 

[Gabs]

What valve stem seals did you use dsm2002?

I'm thinking 09-0566-501-M104 is the one I'm looking for? Can you confirm?

[dsm2002]

To be honest I do not recall. I think they were Elring's. I do not think the ones you are pointing out are correct.  E30 M42 has 7mm valve stems and the standard part number is 11 34 9 059 171 (see the first link below). This part number is also used in early E36 M42s until Sept 1992 which also had 7mm valves (second link).  From Sept 1992, BMW swapped to 6mm valves with a different part number viz 11 34 9 065 438 (third link).

E30 M42
Pre-Sept 1992 E36 M42
Post-Sept 1992 E36 M42

This is the part number you may need: 11-34-9-065-438-M104

You may want to confirm with Pelican