Cam Box Torque

[rebar1111]

when installing Isky high rev valve springs in a 2L TC with stock head specs, what is the recommended torque for the cam box to head bolts? The manual says 18ftlbs, but shouldn't it be more due to increased spring resistance?

[rebar1111]

A further clarification is that the cams are also a higher lift (10.25mm).

[vandor]

No, the bolt torque has nothing to do with spring rate of the valve springs.

[rebar1111]

Vandor: Of course it does. The bolts cause the springs to compress (more pressure if higher k value) and further (if higher lift cam).

[engineerted]

Vandor, is correct! Bolt torque has nothing to do with cam lift or spring pressure. Each of those bolts torqued to 18 ft-lbs has and equivent clamp load of 4-5k lbs. There is sufficient clamp load for any cam or spring you want to run. The cam carrier is not going to move. Now one thing to look for is threads that might have started to pull out. What typically happens is that some PO may have tried to run the cam boxes down with one bolt. Not A good idea. You need to try to run them all down evenly. Turn each bolt a few turns, starting in the middle of the cam box until the cam box is seated, then torque them all down.

Ted,

Engine Assembly and test engineer, Ford motor company.

[rebar1111]

I would agree with you that the torque has no affect on the spring pressure or valve lift, but the opposite is true. I guess I will concede to torqueing to 18ftlbs and watch for thread stripping. The effect of lift and additional spring pressure should not be significant in the torque value.

[Ramzi]

One would think if torque played any effect.. then composition / thickness of the gasket would make even more of a difference.

Never heard of such. Just wondering where you got that information... I open to learning something new

Ramzi

[engineerted]

Yes, we understand that it takes a certain amount of torque on the bolt to collapse the spring when seating the cam box and the addition lift of the cam will impart higher loading of the cam box bolts. But it is truely insignificate. Gasket relaxation, has more effect on prevailing bolt torque then the actual dynamic loading induced by the camshaft.

Tip, torque the cam bolts to spec then retorque again the next day.


Ted

[rebar1111]

Ramzi: I went to a real engineering school and generally drive a Chevy, not a Ford.

[engineerted]

.???

[fiat218]

Ramzi: I went to a real engineering school and generally drive a Chevy, not a Ford.

[131]

Ramzi: I went to a real engineering school and generally drive a Chevy, not a Ford.

If you have all the answers, why ask the question?

[Ramzi]

Ramzi: I went to a real engineering school and generally drive a Chevy, not a Ford.

And Csaba Vandor (or Vandor as he is know here) is a mechanical engineer and had a similar as Ted and mine.... So perhaps being one doesn't necessarily mean they all agree. Please let us know the backstory to your question. Oh, and I'm not sure i understand the Chevy / Ford comment either.

Ramzi