new (sort of) 535i - questions

[cadet x]

howdy,

im new to the forum. i bought a '91 535 with 167k on the motor. looking to do an overhaul on the head/valvetrain. could you fellas give me some advise? what parts do you expect will need to be changed? i've read that the cams are usually worn at this point; im thinking to raise the rev limit on it and increase the overall reliablility because i expect to put another 100k on it... also, comments on valve work would be appreciated. ive seen on bmwe34.net reccommendations to enlarge the valaves, 3 angle jobs, porting the intake manifold, etc. can anyone comment on the effectiveness?

thanks
ken

[Mr Project]

Cam wear at 167k should only be severe if the oil spray bar bolts have been loose for a while, or some other factor has reduced the oil supply to the camshaft. I'd pop the valve cover off, do a valve adjustment, and a good visual check on stuff before diving too deep into upper-end headwork. My original components are basically fine at 178k.

[Bill R.]

overall reliability..The limit is already high enough and raising it just decreases the engine life on a motor with 167k already on it...
The 4 valve motor in the m50 can tolerate the increased revs easier because it has 4 lighter valves with less spring pressure required to close them.. the effects of valve weight don't effect them as much as it does your 2 valve motor with bigger heavier valves, with your motor its much easier to get the rpm range up into the area where valve float can occur in which case the damage will be expensive.... So I would live with the stock rpm limit on the m30 for maximum reliability.... The factory did a pretty good job on the port design and the manifold already also, without spending quite a bit of money its going to be hard to gain anything with the typical porting and polishing that locals may do, in fact they may hurt the flow more than they help it.. The gains in this area are small and typically expensive. Jmho.







howdy,

im new to the forum. i bought a '91 535 with 167k on the motor. looking to do an overhaul on the head/valvetrain. could you fellas give me some advise? what parts do you expect will need to be changed? i've read that the cams are usually worn at this point; im thinking to raise the rev limit on it and increase the overall reliablility because i expect to put another 100k on it... also, comments on valve work would be appreciated. ive seen on bmwe34.net reccommendations to enlarge the valaves, 3 angle jobs, porting the intake manifold, etc. can anyone comment on the effectiveness?

thanks
ken