motorsci 0 Posted February 9, 2018 This is a old rocker Iam lightening has any one else done this ? It's 10 grams lighter it's not a finished product I just started Share this post Link to post Share on other sites
grannyknot 18 Posted February 9, 2018 Drilling holes in things certainly removes some weight but in the case of rockers you are also removing strength, if those bend or break it could destroy the valve train, some pistons and maybe the cam. Hard to believe the Nissan engineers just threw more weight on the rockers for the hell of it. Share this post Link to post Share on other sites
z240 15 Posted February 9, 2018 The holes might not hurt the bending strength much, but removing the "I-beam" top and bottom flange sure as hell will. Stop. Please... Share this post Link to post Share on other sites
Chickenman 12 Posted February 10, 2018 I'd be worried about stress risers from those drilled holes. How many RPM's are you planning on turning with this engine? Share this post Link to post Share on other sites
TimZ 22 Posted February 10, 2018 (edited) 23 hours ago, motorsci said: This is a old rocker Iam lightening has any one else done this ? It's 10 grams lighter it's not a finished product I just started I did something more like this: Edited February 10, 2018 by TimZ Share this post Link to post Share on other sites
Chickenman 12 Posted February 10, 2018 ^ That looks a lot safer than drilling holes and creasting stress risers. You're actually removing stress risers by polishing. Not that I've ever seen a stock Nissan rocker break in two. The " Forge " be strong with these. Share this post Link to post Share on other sites
TimZ 22 Posted February 10, 2018 (edited) 17 hours ago, Chickenman said: ^ That looks a lot safer than drilling holes and creasting stress risers. You're actually removing stress risers by polishing. Not that I've ever seen a stock Nissan rocker break in two. The " Forge " be strong with these. Yeah I had some time on my hands while the block was at the machine shop I'd be a bit leery about drilling holes too - these rockers also weighed significantly less (don't remember the amount offhand - it was several years ago) and have had no issues whatsoever. To Chickenman's point, I also paid a lot of attention to details like eliminating potential stress risers, trying to get the direction of grinding/polishing aligned down the length of the part, and spent a lot of time polishing them. Those took me roughly 8 hours each to complete. Edited February 11, 2018 by TimZ Share this post Link to post Share on other sites
grannyknot 18 Posted February 10, 2018 6 hours ago, TimZ said: Those took me roughly 8 hours each to complete. and how much weight did you manage to take off them? Share this post Link to post Share on other sites
Leon 39 Posted February 10, 2018 23 hours ago, grannyknot said: Drilling holes in things certainly removes some weight but in the case of rockers you are also removing strength, if those bend or break it could destroy the valve train, some pistons and maybe the cam. Hard to believe the Nissan engineers just threw more weight on the rockers for the hell of it. It's not really for the hell of it but for manufacturability, i.e. at some point you're adding steps and time to your process for diminishing returns. They can be further optimized for specific applications, as Tim has done. Doesn't mean that the Nissan engineers purposely threw more weight on them, nor does it mean that Tim necessarily knows something the engineers didn't. It's all a matter of application. I also don't see a great case for a broken rocker destroying pistons or the valvetrian. You can nick a cam lobe maybe. E30s break rockers on track all the time, swap the offending rocker and off you go. Share this post Link to post Share on other sites
TimZ 22 Posted February 11, 2018 5 hours ago, grannyknot said: and how much weight did you manage to take off them? As i said it was several years ago and I don't remember the exact amount. There was a significant amount of material removed, though. I went and found the thread where we were discussing this at the time and it appears it was on the order of 3 grams/rocker: Share this post Link to post Share on other sites
Tony D 151 Posted February 12, 2018 it's all a nice exercise... Have titanium valves, retainers, spring keepers? Well then lighten that reciprocating end and run a lighter spring, you might be good to 24,000 rpms! stock nissan rockers on our bonneville engine were stable to 13,000 rpms in our testing. I think valve, spring, and cam profile selection play a much more critical role. If you note the E-Motive guys polished theirs similar to TimZ. We didn't even do that, though I have in the past on other engines (Yamaha....) 1 Share this post Link to post Share on other sites
motorsci 0 Posted February 12, 2018 Thank you all for your input I have titanium retainers locks and DSI valves from Datsun spirt I have a good unmolested. Set of rockers to put in but just enjoying a little time off work and waiting for the machine shop have a press with a tension gauge and was going to make a fixture to measure the deflection at the tip and what it takes to break it compared to a stock rocker here is a pic it ready to polish 66 grams Share this post Link to post Share on other sites
motorsci 0 Posted February 12, 2018 If I understand it correctly it’s like a stack of straws when it bends Share this post Link to post Share on other sites
motorsci 0 Posted February 12, 2018 They were 78 grams and now weigh 66 Tim Z Share this post Link to post Share on other sites
motorsci 0 Posted February 12, 2018 I read the topic That dragon fly started maybe iam simple but my plan was to measure the before and after valve train weight and figure the difference as a % then subtract that from the valve spring tension and order springs Share this post Link to post Share on other sites
Flexicoker 10 Posted February 12, 2018 Removing the flanges of the I-beam shape is the most inefficient way to remove weight. I would strongly suggest not using that part if that is where you removed material. https://en.wikipedia.org/wiki/I-beam#Design_for_bending Share this post Link to post Share on other sites
motorsci 0 Posted February 12, 2018 I read the topic That dragon fly started maybe iam simple but my plan was to measure the before and after valve train weight and figure the difference as a % then subtract that from the valve spring tension and order springs Share this post Link to post Share on other sites
motorsci 0 Posted February 12, 2018 I’ll probably just by a set of Kameari rockers there 57 grams Share this post Link to post Share on other sites
