M20 rocker arms and valve adjustment

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zracer22

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I've been racing E30 325is cars for 4 seasons, and just recently broke a rocker arm for the first time. Nice clean break, and no other damage to the new motor. In fact, I was able to change it with out pulling the head. The rocker shaft slides right thru the cam gear. I have two questions. Is this common on the M20? The rocker certainly appears to be the weak spot. Does anyone have and tips or trick to advusting the valves?
 
Be very careful where you buy the rockers. I had a very similar problem on my 320i using cheaper aftermarket parts. Unfortunately, it took me a couple of times to figure out that the rocker would break first, then fall under the cam and snap it also. Never had the problem again when I switched back to OE BMW parts.

Grafton
 
I'm not too familiar with racing cars with pushrods...
wink.gif
but can you just use the old Chebbie trick of tighten till they stop making noise, then another 1/4 turn?

Of course, just 'cause it works for the old Suburban doesn't mean it'd be good enough for a real racecar...

------------------
Vaughan Scott
Detroit Region #280052
'79 924 #77 ITA/GTS1
www.vaughanscott.com
 
Originally posted by 924Guy:
I'm not too familiar with racing cars with pushrods...
Click to expand...

No pushrods here, just rockers.

Adjust to the factory specs w/ a feeler guage and a small allen wrench, unless you want to buy the fancy cust BMW tool...
 
What GKR_17 said. Always use OE BMW rockers bought at the dealer. I used these and never had a problem with my M20. I know others that had problems using aftermarket rockers.

Good luck.

[This message has been edited by Bruce Shafer (edited April 22, 2004).]
 
joelg has had numerous issues with broken rockers. it is a relatively common m20 issue. my e30 m20 race car has run 4+ seasons with no problems though.

marshall
 
I think it comes down to luck. There were 4 broken rockers (that I know of) at the bmw club race at vir last weekend, one in a an m20 and 3 in m10s.

none of them were mine for a change
smile.gif
 
There is usually a relationship between broken rockers and and a tach telltale needle, especially with aftermarket rockers. Get the rockers with the roundel on them.
Dave Ebersole
O=00=O
 
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