Boost,

Hell, there's people 3D printing them for smaller, high RPM engines. I don't think they need to be any stronger than you already get from just making them from bar stock Ti.

My questions arise from the wondering if the only reason we've not seen them is the cost. If that's the case, I could very easily be talked into making a set for somebody to test in a "junk" engine. I'd be more than willing to do so, but I don't have that junk engine lying around, and likely won't.

I think the mechanical properties are there and I also think there'd be benefits. There's a reason we have aluminum rockers on the market, and reasons they don't work when they don't. Just wondering if anybody has ever actually tried them or seen or know of them tried being tried.

Thanks. Brad.
(937)545-8991

I got a bike with titanium rods in it. The rods where made in Russia in 98 I think. The engine was originally built for drag race but now it just have a great pension in one of my bike builds.

Vert cool scoot brother!

Peter,

Yup. I had a customer (RIP) in Kalifornia who had literally hundreds of millions of cycles on some of the titanium connecting rods I'd made for him for his 3.5cc single cylinder two stroke engines he ran in his record holding model boats. These engines were running in the 36-37K RPM range, under load. I believe he still holds the record for the fastest six lap ET across all classes in NAMBA with a Sport20, amongst boats running anything from 1.5cc single to 30cc twins.

This is actually a 7.5cc boat. The 3.5cc boats rev considerably higher.

I know what titanium will put up with. But connecting rods are altogether different from rocker arms, in regard to the forces they experience. I'm just wondering if anybody's actually been there and done that.

Thanks. Brad.
(937)545-8991

I bought a couple sets of the Crower Stainless Steel shaft mount rocker arms. I was running the Jesel aluminum full body Shaft Mount rocker arms back in 2004/2005 when D. Wesseldyk was building my NA 565's----no problems with those Jesels, but of course my 565's were very mild with my baby hydraulic roller cams with only .601"/.619" Lift and 232*/239* duration spinning them at 5600rpm on top.

When I dis-assembled my engines after about 220-hours, the Jesel's looked and the bearings felt fine, but the idea of how "aluminum" becoming fatigued/tired over X amount of cycles and possibly failing/breaking made me think twice and I decided to buy the Crower Stainless shaft mount rockers after learning about how steel has no-where near the fatigue if any, compared to aluminum.

I like the idea of lightweight aluminum, but not at the expense of durability/longevity for hard endurance stuff like marine hi-perf engines for offshore boats.

There's a machine shop in Illinois outside of Chicago that sounds like they have a very stellar reputation for building hi-perf and racing engines ----including marine hi-perf engines--- for many years and their shop even have won some highly touted awards in the past few years.

I called their shop a few weeks ago and spoke to one of their owners about one of their Cnc machining processes. He was very kind and professional and after spending a few moments explaining some of the things about their Cnc stuff, we got into a conversation about the valve train of a BBC...and more specifically about various rocker arms, etc.

I was telling him a little about my 565cid engine application for marine offshore use and that I was swapping out my Jesel aluminum shaft mount rockers for a stronger, more rigid/durable steel shaft mount rockers and in so many words he told me---that for my application I it wasn't necessary to use a steel shaft mount rocker arm system with the steel being heavier over the valve, possible valve float, etc. verses an aluminum one, especially for the cost and that I was going way over what I only needed--- And I explained to him;---- It's okay and that I do not mind a little "over-kill" with a steel shaft mount system including the extra costs involved especially on a BBC where I have always heard that the BBC has a reputation for its valve train being the weakest link of the engine and also explained to him that I wanted to ensure the stability of the valve train of my engines especially for marine offshore hi-perf boating use---and that I didn't mind sacrificing a little power for good durability/longevity..... and he said; Yeah I understand about sacrificing some power for endurance, etc, but you're over-killing it to the extreme where it could actually come back and bite you and hurt it more than you're helping it.------ (What???)

So, when he told me that I thought to myself---whether he's right or wrong that's something I have a very difficult time believing and I didn't want to press or argue the issue any further with him. I have never heard it explained to me that way before---maybe the more expensive costs involved with steel and that it's heavier, YES!!!---but not because it will cause more harm than good.... or where am I?

Anyone care to explain that one to me??? ----How can a steel shaft mount rocker arm system with more ridgid strength and durability have an adverse effect on a BBC valve train system compared to an aluminum shaft mount rocker arm system? What am I missing? I just don't get his philosophy/reasoning.

Kaama, those Crower BBC shaft rockers are not cheap at all. 3 times the cost of their stud roller rockers.

The shaft mount style steel, can be made with less material. So the weight is not a 1:1 exchange of mass weight. Common knowledge, but worth mentioning. Comp seemed to always speak to their pro-mag rollers as having less inertial energy required vs aluminum.
​​​​
As for the engine builder's concern of overbuiding:

Your rpms are pretty mild at 5600.
​What does a spintron say for the steel options vs alum?
Total inertial load of the rocker on the shaft fulcrum is what matters to the spring trying to control the valve.

I can't see your extra weight and inertia with steel being an issue.

These rockers are used by guys going 7500+.

https://www.speed-talk.com/forum/viewtopic.php?t=49740

From Brian W @ Speedtalk link pg 2.

"Several years ago while testing 360 ASCS sprint car engine on spintron at comp cams we found the steel crower rockers to be best for our application. Also tested were Jesel and T&D aluminum rocker setups."

Hard to argue with spintron results.

​​​​​​The valve spring weight is also a large factor.