K&B 3.5 Cranks...

[oldlugs]

Hey gang, for those of you who've done lots of playing with K&B 3.5s... Did the 12mm crank really limit RPM potential of the engine, or was it changed to 13mm for reliability issues? Was the 12mm a poor breather?

Thanks again!

Duane

 

[153stars]

Hey gang, for those of you who've done lots of playing with K&B 3.5s... Did the 12mm crank really limit RPM potential of the engine, or was it changed to 13mm for reliability issues? Was the 12mm a poor breather?

Thanks again!

Duane

I ran the inboard verson ran great on 45% small mono would push a 640 or 642 at sub surface but broke about a crank per gallon . I read guys would heat them to take some temper out . went to 13mm and cut off PTO pin never broke one again. THey ran the same for me before the sleeve got too loose and bought more race ready boats. The stuff I read was in this forum somewhere,, heck run the SH%$ out of it if it cracks get a 13MM crank& housing a bearing and your back in action.

 

[VansRacing]

The 3.5cc stock K&B has some exhaust related issues that need to be resolved before that question can be answered.

-Carl,

 

[oldlugs]

The 3.5cc stock K&B has some exhaust related issues...

-Carl,

I assume you mean the restrictive, stock lower...? Assuming I'm using a good tuned pipe, then...?

Just wondering if the 13mm revs noticeably higher & makes more power at high revs than the 12mm...

I know my question seems nutty, given the availability of 13mm cranks, but I've now got several new 12mm McCoy full circle cranks to play with. I know that they'll break too (got a cracked one here), but I can only guess that they're tougher than stock K&B 12mm cranks. BTW two of the McCoy cranks I have are outboard cranks, with long pins!

Duane

 

[Boatshop]

Hey Guys

If anybody is interested, I stopped into PEPPER HOBBIES, in Odessa,TX today.

He has a large box of K&B 3.5 OB 12 mm pistons, sleeves, top ends, cranks, you name it.

The phone # is 432-550-0426

Dave

PS: New parts, not used

 

[Martin Schloegl]

Is it possible to run a 13mm crank in a 12mm engine with good results?

 

[oldlugs]

Is it possible to run a 13mm crank in a 12mm engine with good results?

Yes, but you'll need the 13mm bearing housing and the 13mm bearing (besides the crank).