My '72 Alfa GTV had 'em & leaks,funny carbies etc (archive)

the m50tu, if its any consolation however the valve stem was reduced to 6mm from 7 mm on the M50 to reduce moving mass and improve flow through the head. Also all the M50TU's were Vano equipped, the TU stood for technical update, which meant it got lighter pistons with shorter skirts, lighter rods, single spring valve springs, lighter valves retainers, hydraulic buckets. A sheetmetal damper instead of a cast damper that is also lighter. The M50 didn't have knock sensors and the M50TU does, so you can run lower octane without damage, just a big loss in power. And compression was upped to 10.5 to 1 on the M50Tu from 10.0 to 1 on the M50
Hi Brian ~
Congratulations you have the M50 engine in your 525i! There's no timing belt. It uses a timing chain. The M50 was designed with low cost of maintenance, longevity, and economical operation in mind. Additionally, you have the following features:
* hydraulic valves - quieter operation and no adjustments!
* four valves per cylinder for good breathing a good performance across the rpm range. I believe the exhaust valves are sodium cooled - they're hollow and filled with sodium which is a metal that melts at a low temperature and conducts heat from the valve face as it circulates within the valve. The valves are $25 each via mail order.

* dual overhead cams
* individual ignition coils over each spark plug
* this is a high-compression engine with knock sensors - use ONLY PREMIUM !!
* VANOS? You may want to check to see if you have the VANOS engine. I'm not sure what year the M50TU engines with VANOS were installed. It variable valve timing. The latest iteration is even more sophisticated. Perhaps someone on the board can tell us what year VANOS came out.
Happy driving,
Larry

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