M42 cylinder head Valve guides

[shady62]

hi guys im in the process of getting hold of a set of supertec oversized valves but i have a question. currently i have an e36 M42 in my E30 IS as previous owner trashed the engine, i have a cylinder head in my workshop that i am going to have worked at CNC place but i need to supply the valves with the head. this cylinder head came from an e30 (so 7mm valve stems) but as far as i can see supertec only sell the 6mm valves which is fine but what i would like to know is whether the e30/e36 valve stems are identical apart from the internal diameter? or will i need to order a specific type of valve guide to fit the e30 head but with 6mm dia. valve guides.
thanks in advance chaps.

[shady62]

also, is it really worth going down the road of their master valvetrain kit? im not planning on having a high redline or screaming the shit out of the car, the work is being done for a bit more power and help it breathe easier, not keen on turbo or SC its cheating ;-)

[benz-tech]

Since you are not planning a higher redline I wouldn't get those valves at all. A mild port and polish together with maybe a slightly larger intake cam (S50 copy) is what I will be using. MM was confident that that would take my 1.95 L engine to 7k. Right now my intake cam is at Delta cams for a regrind copy of an S50. Should be about a hundred bucks they say so I will post as soon as I have solid info.

[shady62]

ok, keep me posted. any ideas on the guides? im guessing the cylinder heads would be identical, surely mr bmw would have just changed the valve guides rather than change part of the head design?

[Darky]

Hi

First you need to knock one out. You see there outside dimension can vary quite a bit from .432-.436, no idea why. Typically one size for exhaust and the other for inlet guides.

Then contact a few sellers and order what you need 16 m52 valve guides. Achilles Motorsport is where I got mine from. Great service and product!

I found a lot of people got confused when you asked for 6 mm m42 valve guides, annoyed the crap out of me. Usual response was so "you want 16 7 mm m42 guides" drove me insane.

If you are changing from 7 mm stem to 6 mm stem you need to change the retainers as well and to match retainers with existing springs is another pain. So your better of changing the whole spring and retainers in one go.

I got those from ams Enginering, they mainly do honda.
They will ask what cams and valve weight, redline are you planing and make you a set for your engine.
This is quite important too stiff on a mild cam is wasted power, not stiff enough on large cam can cause the valve to bounce.

My 2c worth
Rohan

[shady62]

thanks rohan, exactly the answer i was looking for! much appreciated