8 replies to this topic

[Retroman]

Anyone one have a diagram showing cam timing gears and advance direction ?

 

Pictures speak a thousand and all that...

 

Not good at making diagrams myself

[r.tec]

Hello,

do you mean something similar to the picture attached? I made this with the aid of an old version of Desktop Dyno.

[Retroman]

Thanks but no,  need one of the cam gear(s) showing the direction to advance the cam either a photo with lines or a line diagram, trying to explain fitting an offset cam key for someone

 

Where do you get the " CamManager" ? looks very useful

[r.tec]

CamManager is part of the DesktopDyno2000 software I bought many years ago.

 

For your help: nearly all engines run anti-clockwise when you consider the the timing gear side as the front...

[gazza82]

I think this is right. My brain says that you want to move the cam to open the valves earlier so it has to be moved clockwise. That would mean the offset woodruff key needs to be placed so the cam is further round clockwise to the cam drive gear ... but I am no engineer so I may have got this wildly wrong (plus I'm doing this when I should really be working!)

 

So on the left is the standard key, and the right is an offset pushing the cam lobe slightly earlier in the cycle.

 

 

 CamAdvance.jpg   14.36K   0 downloads

Edited by gazza82, 12 December 2018 - 12:18 PM.

[Wiggy]

That looks right to me. I had to wrestle with my mind quite a bit to work this out recently too. My arms flailing about pretending to be sprockets, chains and a cam.

Diagram on the left would have maximum lift at (numbers plucked out of thin air) 110° ATDC.

Diagram on the right has ADVANCED the cam timing by (let's say) 2°. So it reaches maximum lift EARLIER, at 108° ATDC.

[gazza82]

I may not have the lobes far enough apart to show it properly .. my PC based drawing tools (and skills with a mouse) are limited!

[Spider]

I have been meaning to do a diagram to include in my workshop folder, but haven't gotten there yet.

 

In the mean time, I just draw a diagram in felt tip marker on the front on the engine or on the sprocket.

[gazza82]

I've got to do this one day but with a vernier drive .. so by my reckoning if I need advance the inner part of the cam gear turns clockwise and the outer anti-clock, and if I have to decrease it, gear sections move the other way. Bet I can't find this post when I need it!