Hi Y'all

I have been offered a 1916 motor with a 'roller crank'., Can you tech wizards tell me what this means to the performance and longevity of a motor. Are the roller cranks desirable? Pro's and cons please

means $ to replace and some one that can fix it in perth RIGHT !
There a roller bearing crank needle type
motor can rev fast and free
from what i have seen and fixed short drag racing ,thats about it .

When going hard the crank can some time * move * on the centers ,this makes the motor go out of balance ,and stuffs it up big time .

my two bob

were you going to put this in the 15 window ??
Or the look out for airplane split as these all have reduction boxes dont they ??
or were you going to put this in the bay for going across australia in ??
or are you going racing ??

Or none of the above. Just learning mate. I am just learning and dont want to be stung by something that sounds good but ends up as money down the drain.

So many pitfalls and so little money!!!

All I know is that I have a good friend that built a big bore vdub motor and had a roller crank in it...it went like stink but that may not have been due to crank. I heard that the roller crank revs higher but don't know re reliability or worth the bother

Roller cranks do exist and are very expensive.

http://www.carquip.com/parts/356/engine/crank/index.asp 

Roller cranks are a 3 piece crank - made from 3 separate pieces, pressed together so that you can have roller / needle bearings for the main bearings, instead of the standard plain bearings. The idea is to reduce friction on these bearings, thus allowing more power, faster and higher revving.

In practice, from what I have heard, they can be expensive and you need some real know how to make sure they go together straight and correctly.

I believe that Dave Becker on this forum is running a PPG roller in one of his big motors - he will certainly be able to give expert advice whereas I can just tell you what I have heard.

Cheers !

No I don't run an SPG roller crank, mine is an old Okrassa, made around the same time but plain bearing.

The SPG crank is like said above made in parts and pressed together with roller bearings on the big ends, they were counter weighted too. If you have a stuffed bearing it is very hard to replace as it has to be taken apart, and put togeather in the right place, something not many can do.

People say they rev more, But if you think about it, what happends first when you over rev, Valve float, Roller bearing or plane bearing its still going to valve bounce.

A plane bearing crank can turn to over 10,000 rpm of you have the right valves and springs.

Just stick with a VW crank.

Thanks Dave
This forum shows it's value when you guys share that wealth of accululated knowledge.
I went on the website that helbus gives above and the crank looks awesome but scary..looks like the roller crank came from a Porsche 356 originally

the other issue with roler cranks is generally they use needle roller bearings which are not suitable for high loads, and therefore longevity is not good. there isn't the room to use ball bearing races which are suitable for the loads motors produce, not to mention too difficult!