Any interest in Vernier Cam Gears

[rms]

Having yesterday sheared a camshaft gear drive pin when push starting the car, I am looking at manufacturing a vernier setup with provision for an additional larger drive pin.

The drive pin MAY???? be marginal when used with big cams/springs/rpm.
Dont know if it was caused by something else at this stage (cam brg, bucket, etc.)

The design has to be sorted out and I have no idea of cost.
The centre boss will be NC machined from 4340 chrome/moly and use a modified original gear or a new gear from steel or aluminium.

We will be using them on our engine and if there are others interested I will make a batch.

 

[striker]

Keep us posted on the cost, very interesting.

grtz Thomas

 

[rms]

The camshaft gear to camshaft locating pin looks like it is marginal for big cams/springs/rpm etc.
There are no signs of damage to cams, scissor gears, buckets, springs etc. No evidence of anything else causing the pin to shear.

We do have some bent inlet valves but that was caused after the cam timing went out of position. This is an interferance engine.

May not happen if engine is started on the starter motor or with more normal flywheel/clutch weights.
Now we have to ensure it doesn't happen again (2 x 6mm pins).

 

[steveo]

More cost information as you get further along would be useful for generating interest.
Do you have any work started on the CAD work?
What models do you have in mind for the cam drives?

Any additional info will bring more interest...

Thanks, Steve-O

 

[rms]

Verniers will be for 1UZ non VVt, however can not fit verniers and retain the original distributors on the front of the cams.
Guess thats why non are available.
COP or wasted spark will be OK.

 

[rms]

Design at the moment

 

[Anaema]

what is a verniers gear? it sounds familiar, but i can't pin it down.

 

[cribbj]

Erol, with this vernier, however much the intake cam is retimed, will result in the exhaust cam being retimed by an equal amount, because of the scissors drive, correct?

What are your models showing for optimum timing with something like this?

 

[rms]

John, you are absolutely right. The best you can hope for is to split the difference. We do have the last vernier exhaust scissor gears made by Kelford so we can then set the exhaust seperately.

It is difficult to obtain 'optimum' timing with the cam profiles I have been using. At around .200" lift at TDC overlap you start to run into valve/valve and valve/piston interferance so you cant really change things on the dyno.
Mainly use profiles developed by Cosworth and set to their specs.