Question for engine Builders

[PakMan]

My question is about Rods. BTW, I'm a Scale Guy.

I understand that "in theory" the caged bearing is the best. Thanks Jim Allen for your insight in past posts! My question relates to those of us that are trying to push the enevelope, and learn new things. To be more specific, I have been running K-67 motors. I like to think of myself as an "easy" engine guy. I have run more than 50 times (Hard/Fast) without a failure with the K "caged-bearing". However, when I decided to try some larger, or should I say pitched up/cupped props (Thany you Mark S.) last fall, I ate a caged bearing and about $200 in parts. OK, I am learning.

But, since I can not get New K-Rods from Al Hobbs, I am thinking of having Brad C make me some. My thought is that I should have him make me some that are bushed up top (660 Brass), and maybe bushed down below (old school) until I can get my optimum Pipe, Prop combo figured out?? I could use a full compliment of needles like many suggest, but I really don't like the idea of needles rolling against each other "in the other direction". Does that make sense to anyone??? I think I'd rather use Al-NI-BR on the lower bushing and remove the 15-17 rollers and deal with the downside. Does anyone have any insight??

After I get my set-up figured out more conclusively with regard to speed and Prop selection, I think I will likely go back to the "theory" and use "Caged-Needles".

Thanks for any input.

Sincerely,

David Jensen

R/C Unlimiteds

Seattle, WA

Public Email: [email protected]

 

[DAN MCCORMICK]

My question is about Rods. BTW, I'm a Scale Guy.

I understand that "in theory" the caged bearing is the best. Thanks Jim Allen for your insight in past posts! My question relates to those of us that are trying to push the enevelope, and learn new things. To be more specific, I have been running K-67 motors. I like to think of myself as an "easy" engine guy. I have run more than 50 times (Hard/Fast) without a failure with the K "caged-bearing". However, when I decided to try some larger, or should I say pitched up/cupped props (Thany you Mark S.) last fall, I ate a caged bearing and about $200 in parts. OK, I am learning.

But, since I can not get New K-Rods from Al Hobbs, I am thinking of having Brad C make me some. My thought is that I should have him make me some that are bushed up top (660 Brass), and maybe bushed down below (old school) until I can get my optimum Pipe, Prop combo figured out?? I could use a full compliment of needles like many suggest, but I really don't like the idea of needles rolling against each other "in the other direction". Does that make sense to anyone??? I think I'd rather use Al-NI-BR on the lower bushing and remove the 15-17 rollers and deal with the downside. Does anyone have any insight??

DAVE: Order the aluminum rods from Brad they are the best. You will need no needles,but if you ever decide to run steel rods get a set of CMDI needles for the mac 67. 16 needles is all you need if I remember. Leave a little clearance. Remember to run no less then 20 % oil in your K-67. The weak spot of the engine is the wrist pin. Change it out with a rossi 65 wrist pin

and grind off about 0.022 thousands on the open end. You can get the pins from MORRIS hobbies . They will slide right in . No boring needed. The caged bearings and stock wrist pin are ok if you run a moderate setup. But if you decide to increase the compression run a high load prop or high nitro the stock bearings and or wrist pin will let go. I would replace them asap. After that you will have a bullet proof engine. I think they are the best. Hope this helps. DAN MCCORMICK

 

[PakMan]

My question is about Rods. BTW, I'm a Scale Guy.
I understand that "in theory" the caged bearing is the best. Thanks Jim Allen for your insight in past posts! My question relates to those of us that are trying to push the enevelope, and learn new things. To be more specific, I have been running K-67 motors. I like to think of myself as an "easy" engine guy. I have run more than 50 times (Hard/Fast) without a failure with the K "caged-bearing". However, when I decided to try some larger, or should I say pitched up/cupped props (Thany you Mark S.) last fall, I ate a caged bearing and about $200 in parts. OK, I am learning.

But, since I can not get New K-Rods from Al Hobbs, I am thinking of having Brad C make me some. My thought is that I should have him make me some that are bushed up top (660 Brass), and maybe bushed down below (old school) until I can get my optimum Pipe, Prop combo figured out?? I could use a full compliment of needles like many suggest, but I really don't like the idea of needles rolling against each other "in the other direction". Does that make sense to anyone??? I think I'd rather use Al-NI-BR on the lower bushing and remove the 15-17 rollers and deal with the downside. Does anyone have any insight??

After I get my set-up figured out more conclusively with regard to speed and Prop selection, I think I will likely go back to the "theory" and use "Caged-Needles".

Thanks for any input.

Sincerely,

David Jensen

R/C Unlimiteds

Seattle, WA

Public Email: [email protected]

I got your Response Dan... Thank you. I/W would not let me respond to your response: Here is my Thank You....

Yeah, I've heard that about the wrist pins... actually seen it first hand from some friends that run more frequently. I've been using the - improved wrist-pins (Bored from each end) from Al, but have heard the Rossi 65 pins are good. Also the OPS?? Anyway, I'm aware of that weakness...., and I'm running a couple extra ounces of castor in my fuel to get to the 20 percent number.

Thanks so much for the Brad endorsement, and the other info.!

David

P.S. - Are the CMDI Needles different from the CMB Needles?? Diameter, Heat/Treat, ??? Thanks for the heads up.

 

[dr gary turner]

I have been running k-90 and k-80 motors since they first came into the country. They were initially hand carried in in pieces. We got rid of the caged needles YEARS ago. We run just pain needles without ANY problems. It takes 17 needles for the k-90. The 18th needle will just not quite go in which is excellent. This provides GREAT lubrication and the needles run freely. WE have ran the motors hard in single application and in a twin without any rod or needle baring failures. Gary Turner

 

[PakMan]

I have been running k-90 and k-80 motors since they first came into the country. They were initially hand carried in in pieces. We got rid of the caged needles YEARS ago. We run just pain needles without ANY problems. It takes 17 needles for the k-90. The 18th needle will just not quite go in which is excellent. This provides GREAT lubrication and the needles run freely. WE have ran the motors hard in single application and in a twin without any rod or needle baring failures. Gary Turner

Thanks for your input Gary.

Have you been running improved Wrist-Pins?? I know that I can replace the caged needles with "full-compliment", but was trying to hold on to the "ultimate" in performance as pointed out by Jim Allen. But then again, broken on the side-lines is not better than "less than ultimate" and still running. Your input is noted, and thanks again.

Sincerely,

David Jensen