Why Can't I Read English?

[truckinwagen]

you mean thick enough shim, the hydro cams have a smaller base circle.

[rs899]

Shim?  What shim?  See, I am really confused...are there shims on a hydraulic head?  If so, those weren't included in the kit of parts I fell into....

I know my way around mechanical heads just fine...why did they have to mess up a good thing...progress (mutter mutter) .

Rick

[truckinwagen]

no, hydro heads have no shims.

we were just saying that the hydro cam has a smaller base circle, so if you installed one in a mech head, you would need VERY thick shims.

a mech cam in a hydro head will compress the lifters more than they are designed to be, might work, but not the way they designed it.

[rs899]

Is the normal condition for the hydraulic cam to contact the lifters at all times (360 degrees)?  Or is there some clearance as on a solid lifter system?

The last thing I want to do is have #1 (or any) piston and valves meet again.  I am not too concerned that running a mechanical cam is less than optimal , as long as will it work without damage....

Rick

[truckinwagen]

on both solid and hydro you should not be able to see any gap between the lifter and the cam.

when the hydro engine is running the oil pressure will keep the lifter in contact with the cam at all times, and when off they should be touching, or so close you cant tell the difference.

[rs899]

Well of course, on the mechanical , there is the normal clearance, whatever the spec is .006" intake /.014" exhaust or whatever it is (not reading from the Bently).

So on the hydraulic, with the oil pressure up , the lifters are in constant contact with the cam...hmmm.  Shows how much I know....

[truckinwagen]

well, this is not entirely true, when the cam pushes the lifter down it will force a small amount of oil out of it, and the oil pressure will take a small amount of time to fill it back up to contact the cam again.

this is a very small amount of time, and usually the lifter is in contact with the cam long before the next time it is pushed down again, but if the motor is spun fast enough the oil pressure cannot keep up with the oil being pushed out of the lifter by the cam, making the gap get bigger and bigger, sometimes called valve float.(this can also happen when the valve springs are not strong enough to push the valve back up fast enough in a mech engine)

but for all purposes other than high RPM(which our diesels rarely see) the Hydro lifter is in contact with the cam at all times

[rabbitman]

Unfortunately (or fortunately) I am going to have to use a mechanical cam on this hydraulic head (unless someone has  definitive evidence that it won't work).  The original hydraulic cam was left in the leaky trunk for about a year, and several of the lobes are pitted beyond salvage.

http://www.oregoncamshaft.com/

We've used this place twice with good results, if they have cams in stock you can buy one and use your's as a core or just send it in and get it ground. The cam in my rabbit came from there.....