k-67 engine advice

[Richard Haineult]

Hi,everyone.

Since i'm a new owner of two k-67 engines,i've heard somewhere that i would probably have to change some part like the conrod,bottom conrod bearings and the wrist pin to make the engines reliable for use in heat racing using 50 to 60% nitro.

Any comments,parts numbers or advice would be really helpfull.

Thank's in advance,

Richard

 

[Bob Finn]

We had to change iout the roller bearings in the lwer end of the rod. We installed CMB 67 rollers. Also, we broke several wrist pins in half.. I installed CMB pins in all of mine, but I understand that a Rossi pin also works. I honed the piston and rod slightly and shortened the CMB 80 pin to fit. No more trouble.

 

[Mike Hughes]

The lower caged rod bearings will hold up to fuel with 20% oil. If you start to try and run the motor lean for any length of time you may lose the plastic cage. At which point the needles come out by the crank and go through the motor. Ugly. The MAC or CMB needle bearing elimanate this problem. Another option is to buy a titan rod from Brad Christy for it. It is bushed on both ends.

Mike

PS This is the same for the 81 and 90 also.

 

[Tim_Duggan]

I strongly reccomend swapping out the wristpins ASAP - Rossi or OPS pins fit without mod's. Also CMB67/80 or MAC 67/84 rod needles in the bottom end.

Muck 67 pipe works extremely well on these engines!

Also 15% synth and 5% castor in the fuel - shallow taper angle in the sleeve.