Hurt my crank

It was one of the new cranks. I had just finished polishing it. I broke it right after its first run. I did not use a screw on this one. It was a stud with a machined aluminum "needle nose" spinner. The spinner has a hole through it and I put a piece of #4 push rod steel rod through it to tighten the prop. I think I just dumbed out and over compensated for the pliability of the soft steel pushrod. I think the silver lining is that I now have an exuse to make another order with Bernie, if anyone ever really needs an exuse for that.

Since the engine was running so nicely and well I will definitely get a new crank for it. I think I had a thread on RCG or RCU regarding this engine. I am going to check to see if the new crank made a difference.

Bob

I found the thread on RCU and the engine also had a different piston then. So, with a different piston and standard crank it was runnig at 18,550 RPM. With a standard piston and the KB crank it was running 19,500RPM. Nice difference, I just wonder how much was due to the crank.

fit90 wrote:I found the thread on RCU and the engine also had a different piston then.

Link??

http://www.rcuniverse.com/forum/m_10675185/tm.htm#

GOOD LINK

Above link is now good

Still trying

Bob -

I'm getting a page or topic not found on that link.

andrew

Sorry, I can't figure out how to post a link for this. It was in RCU on 8-18-11.

The computer is way smarter than I am tonight and my treachery is not strong enough to trick it.

Bob

Got it. Sixth post in this thread labeled GOOD LINK. Sorry for the confusion.

Bob

Thanks --- I remember that thread now. Big Al's pressure tap was pretty innovative.

Cox International wrote:...However, please keep in mind that the Killer Bee cranks are softer and not harder than the standard Cox crank. This is what keeps them from breaking during high-RPM or diesel applications. The standard Cox cranks are over-hardended and therefore brittle.

Bernie
www.coxinternational.ca

That's good to know. I want to build a KB. I have an engine with a new crankcase with a brass drive plate, a KB red backplate and a new SPI piston/cylinder. All I need is the crank if I'm not missing something. Oh I guess I need a high compression head. That all adds up to a Killer Bee, does it not?

Yep, TD head, KB crank and, if you don't have one, the KB needle valve.

Bernie
www.coxinternational.ca

Cox International wrote:Yep, TD head, KB crank and, if you don't have one, the KB needle valve.

Bernie
www.coxinternational.ca

Oh yeah, I almost forgot. I used the KB needle in my Medallion. I'll be making my Christmas wishlist soon!

Bernie,

That is a very generous offer and I appreciate it greatly. However, I firmly believe it was my gorilla brain leading my gorilla hand to do harm to my once ready to go engine. On the up side, I took the #4 cylinder and piston and rebored KB backplate and swapped them out with the corresponding parts on another engine that features a beautiful red Halfa works crank case with another polished KB crank. I hope to run it this week end.

I do not know if you celebrate Thanksgiving but I do wish you a happy Thanksgiving and a wonderful weekend. I truly appreciate all of your geneerous support and help with this great hobby.

Bob

This is the engine I will use in place of the pressure tapped one. It was built around a Halfa Works crank case, a #4 cylinder/piston, Galbreath haed/Nelson plug, polished KB crank and bored venturi KB back plate. I will run it today to see if it is any good

Even if it doesn't run well I still think it's pretty.

That is lovely!

fit90 wrote:Even if it doesn't run well I still think it's pretty.

It is indeed a cute little bugger. If you could find a piece of red tubing to replace the yellow NV tubing, you would be strictly "uptown".

Andrew,

That's a great idea. I have never been uptown before so I think I might try to find some red needle valve extension to see what it is like. Thank you.

I just ran it about one can of soda and turkey sandwich ago. All the time I was setting it up I couldn't stop thinking about the tach contest. I had to make a few changes. The #4 piston/cylinder was replaced with a #5 piston/cylinder with a lightened piston. I also tried to do the initial run with only one glow head gasket. I could only get it to either burble for about 30 seconds or start backwards. I upped the head gaskets to three and put on a no drag spring starter. It is a happy little starter now. With Sig Champion 25% and a Cox stiff grey 5X3 it would turn a steady 18.5K RPM after two ounces of fuel. It may not be a barn burner but I am quite satisfied with it. I think after a few more ounces of fuel it may give a little more oomph. Time will tell.

Bob