I am working on a project that involves some fine tuning of the valve train. It would be really helpful if anyone knew how many inch pounds it takes to turn just the camshaft with stock valves. I could take my timing cover off and measure it with a torque wrench, but want to see if anyone has already done it or if they currently have the timing cover off, could test it real quick.

I don't know why you are interested, and I don't have the answer exactly, but I do know that it is very light. The main friction on turning over a crank is the cylinder wall friction. A good set of well lubricated lifters on a cam is a pretty balanced unit where the pressure to compress the springs is offset by the reverse pressure letting off the others.

Hope this helps.

Arn

Arns85GT is right. It should take much to move it all just be real carefull when tooling away on the timing area. bad things happen to good people if it gets screwed up.

are you thinking of manually advancing the timing??

[This message has been edited by gtxbullet (edited 01-18-2010).]

the torque required would vary quite a bit, depending on the cam profile & spring rates.
and, being the 360* turning circle is broken into 6 + 6 "peaking" events on the cam lobes - are you looking for a complete circle average?

Oh i hadn't considered that the closing valves would ease the effort on the opening valves, that makes the required torque alot lighter than I first thought.

hmmm, didn't want to give up my secret but I am working on a VVT pulley that uses centrifugal force to retard the cam timing in the higher RPMs. The cam will not be directly attached to the chain like it is now, input from the crank will go through a group of levers with weights and springs on them, which will adjust themselves according to how fast they spin. Now that's all your getting out of me. A pushrod motor with VVT, i want it.

intresting idea.
I'm picturing a kind of centifugal setup - but the way you desribe yours, I can only see the timing adjusting one way - I dont see how it can "return"

a way I've thought about involves a longer timing chain, and using tensioners to keep the slack to one side or the other, and this would give the timing adjustment. the longer the chain - the wider range you can adjust too. even the stock chain would allow about 2 degrees adjustment. add 3-4 links, and your out to 8 degree valve timing adjustment.

quote Originally posted by Pyrthian: intresting idea. I'm picturing a kind of centifugal setup - but the way you desribe yours, I can only see the timing adjusting one way - I dont see how it can "return" a way I've thought about involves a longer timing chain, and using tensioners to keep the slack to one side or the other, and this would give the timing adjustment. the longer the chain - the wider range you can adjust too. even the stock chain would allow about 2 degrees adjustment. add 3-4 links, and your out to 8 degree valve timing adjustment.

the levers have springs that would pull it back to the stock timing position, also when the crank slows down the cam shaft wont slow until it returns. The inner wheel (one that the cam is directly attached to) will have set screws that allow you to adjust the idle/low RPM timing position. then the outer wheel will cause a certain range of retard-ing adjustment as it runs through the RPM range, prolly 8, degrees away from wherever you set the inner wheel. This way, you can set the cam at 8 degrees advanced position for stronger low end performance, set it at stock position for high end performance, or 4 degrees advanced timing for a little bit of both! It will only be able to adjust one way, but because of the adjustability of the inner wheel, it only needs to go one way. I hope thats a good explanation.

Don't forget that the camshaft also is the drive for the oil pump. This load is not constant due to changes in temp/viscosity and RPM.