C clamp vice-how much force ?

[adomakin]

Im wondering how much force i need to apply to the left chain idle arm when clamping it up to check my measurements. im thinking that the oil fed hydros can't exert THAT much pressure....or am i wrong? should i be using one easy hands worth (in terms of amount of force required to close the clamp) to close the clamp or more force than that?

[1972_911T]

Hi Andy hope my clamp stands been put to good use The thing to remember is that the main load on the chain is not coming from the tensioner, the tensioners main job is to take up the slack preventing the chain rattling around, All the load on the drive side of the chain is coming from the the engine having to spin the camshafts at between 500 - 3000 rpm. (half crank speed) so with all your valves and spings in place this is going to create a much grater load on the chain than the tensioner ever could. What you need to do and this is the bit thats subjective is to try by using the clamp on the tensioners to put an similar amount of load in the chain as when the engine is running.

I know im falling short here of actually telling you what you really want to know (how much load) but as I have not run my engine since I did mine Ill leave it to the people who have put there practices to the test to tell you there methods.

Steve

[adomakin]

makes sense steve and yes, your clamp stand is being put to very good use! (such a simple tool-such an important job!) Ill get it back to you asap. (don't have your address though!)

[Eagledriver]

I think some of us are overestimating the tension the chains are under. There is no more force required to keep the cam spinning at 3000 RPM than there is when we turn the crank by hand during the timing process. In fact the tension may be less due to the oil pressure in the cam journals and the oil spraying on the cam lobes. The chains increase in tension when the engine is speeding up and a decrease when the engine is slowing down but the steady state load is not that high.

IMO the amount of tension you should set the cams with is just enough to take out the slack and put a small amount of additional tension. I think that tightening the clamp with just your thumb and one finger should be about right. Think of the tightness of a fan belt instead of the tightness of a piano string.

-Andy

[adomakin]

cheers Andy. sounds like i need to back off a little on my clamp.

[ChrisBennet]

Andy,
I posted some info that may be of help in this thread: Cam timing and chain tension
-Chris

[adomakin]

thanks for your help (again!) Chris. sort of feel a bit silly for not finding that thread in the first place! anyway, at least this thread has thrown a bit more light on the subject.

[ChrisBennet]

Originally posted by adomakin
thanks for your help (again!) Chris. sort of feel a bit silly for not finding that thread in the first place! anyway, at least this thread has thrown a bit more light on the subject.

I had trouble finding it myself (!) so don't feel bad.
-Chris