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Discussion Starter · #1 ·
As per Jim K. one can use the BMW 325i production parts cause of the valve shape and 8mm stems. I've tried sourcing these today from a local parts store.

Thing is I can't seem to find any 325i valves with 8mm stems, the older E36 box shape valves are 7mm and they go even smaller with the newer models.

Have anyone else gone this route and where can I find these ?
 

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Discussion Starter · #3 ·
I've had a look at the 318i valve sizes and they seem to be the correct size for what I'm looking for, Jim's book threw me a bit off course mentioning the 325i, should be the 318i Coupe (1984-85):thumbup:

- Intake Valve (46 mm) (8 mm Stem)
- Exhaust Valve (38 mm) (8 mm Stem)
 

· Richard Jemison
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8,978 Posts
Valves

What are the valve`s lengths? lock groove design? type of collets(angle)? what spring retainer to match?, springs? shims? etc.

If you are doing this to make more power (unless you think your motor will run 9000 RPM) you are wasting your time and money.
 

· Richard Jemison
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8,978 Posts
But....

Hi Richard,

Valve overall length is 106,5 mm
3 groove collets and spring retainers original BMW
shims Alfa 75 Twin Spark (8mm)
The valves are 1.5mm too long. How are you going to deal with that?

If you reduce the Base Circle of the cam to accomodate an extra .060 valve length, then the cam`s bc has to be reduced .120 which reduces the stock BC from 1.080 to .960. Then you are dealing with a "junk" cam.
If you cut off the hardened tip of the valve will there be room for the valve shim to seat on the valve and not touch the colletts/keepers?

What are you really trying to gain???
 

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What are you really trying to gain???
Hi,

I am not trying to gain anything, I just wanted to give Shane the Information he asked for.
These BMW valves are not a direct fit, but if you are doing a complete head/valve job as Jim K. mentioned in his book it is possible to settle the necessary new valve seat rings a little bit deeper... it won't cost more money.
The valves can be shortened by 0.5mm without having contact shim/retainer.
If you are going this way of modifikation you might use a non standard performance cam, which usually have a smaller bc.

I have done above mentioned with a CB 12, bc 27 and the used shims are 2,325 to 2,525 mm.

Volker S.
 

· Richard Jemison
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8,978 Posts
Seats

Jim K. mentioned in his book it is possible to settle the necessary new valve seat rings a little bit deeper... it won't cost more money.
That`s exactly what you don`t want to do as it only makes it worse!

There is no power gain from this foolishness.
 
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