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first time post here so thank you all in advance for any expertise and experience the hive mind is willing to impart.

I’ve got a BMW M62TUB44 V8 that I pulled from an X5 overland project car and replaced with a new motor. My plan is to rebuild that 4.4, assuming the bores are good when I tear it down, for a street/track car. It will be my first engine rebuild and while I do understand the limitations of the basic motor, I hope to get a little more power out of it via different heads which will allow for a lighter valve train, better cams and maybe some porting, etc. nothing cosmic, but perhaps 300 to 350 hp at 7000 or 7500 rpm. This project is as much about the journey as the final product, so I’m trying to get as smart as possible on the various aspects first.

I know a lighter valve train is better, so I’ve got a line on two different replacement tappets/ buckets for the OE pieces. Both are within a thousandth or so diameter wise of the OE buckets, and weigh 6 to 9 grams less, which I think is significant. There are some height differences, which will lead to a future shim question im sure) but my immediate question is the lightest of the two buckets (a custom piece from a specialty shop) doesn’t have an oil groove, whereas the OE BMW ones do. I understand the buckets turn while operating and the groove must them allow for continuous oil pressure to the bucket, so will the lack of a groove be a showstopper in my using the lightest of the two replacement tappets?

Thanks all

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  • Welcome to Motor Vehicle Maintenance & Repair! A comment about valve springs: they do not add weight to the valvetrain. They counteract the weight of the drivetrain. There is a reason the cam shaft manufacturer recommends the inner spring, it's because they know the valvetrain needs help to maintain stability and not get into valve float. Jun 20, 2023 at 16:44

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With or without the groove should not be an issue. I'd assume the non-OEM manufacturer took this into account when creating the lighter bucket in the first place. If it is a worry for you, consider not changing out the buckets and taking weight away in other areas.

Going lighter will definitely help with getting to the higher RPM. The biggest problem with taking your engine to a higher than redline RPM is valve control. The redline of the M62TUB44 stock is 6100RPM. Taking it to 7000-7500 will require a lot more than lighter buckets, though. You will need different valve springs with a higher spring rate. You should talk with your cam manufacturer to see what they recommend. Along with the new springs, consider getting lighter valves (titanium or hollow stem valves on the intake, sodium filled on the exhaust) will help tremendously. Also titanium keepers and locks. If you lose valve control, (typically called valve float) it will absolutely kill power. It is also detrimental on the valvetrain and can damage it if it persists for too long (holding the RPMs at valve float for any length of time).

There are other factors you need to consider when running an engine to higher RPMs, but I take it you will be asking those questions later, so will leave that for another time.

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