Thank you!!!

Marco wrote:

My question is: is it possible to install 1.6 ratio rocker arms suitable for chevy (3/8" stud) onto a 289 Ford head?
Studs are same 3/8", ratio is the same, what is the difference? Pivot height with reference to a imagine line between rocker pushrod point contact and valve stem contact maybe?
Marco

Although they share the same 1.6 ratio the distance from the center of the pivot to the valve stem contact pad and the distance from the center of the pivot to the pushrod cup is different. You can't use the Chevy rockers.
 

Marco wrote:

yes, sure, I understood. 1.6 ratio is on each rocker applied to its engine.

Just to verify- the rocker ratio is calculated by dividing the distance from the pivot to the valve stem by the distance from the pivot to the pushrod.
Although those distances are different between a Ford rocker and a Chevy rocker they both equal 1.6 when divided.
 

I hate when that happens.  Probably it just wasn't listed right.  Drives me nuts when companies do this.  Its a minor oversight that creates a huge pain for the end user. 

I think do not exist the right part, fortunately I bought only one piece to try the installation. I think this is not for stud installation.
Now I will procede with camshaft replace, I think it's the best solution to go in one certain direction, have not future troubles and save time.
I would like to make a consideration, I bougth the piece not from summit but from another vendor which have not specify the description, in any case it is probably wrong the description in the summit web page.
Thanks all for supporting. Marco
 

Last edited by Marco (12/09/2019 1:52 AM)

I understand now that this type is not adjustable. The pivot is tightened to the threaded hole (5/16") on the boss on the head, the pushrod have it's properly lenght so all the geometry is correct once pivot is tightened.

This would not be a problem because 289 my66 heads are self align rockers (no rail), the point where the pushrod pass through the head is slot type not an hole and guideplates do not exist (this is stock configuration).
I thought to modify the pivot, cut the bottom, drill to proper diameter.
Making this the pivot will work like the semispherical piece. but I prefer not to try with experimentation, I have not a spare engine and I would like to save the original components.

Compcam XE256H-10
valve lift  .477 - .484

Marco wrote:

Compcam XE256H-10
valve lift  .477 - .484

You can use stock rocker arms for that cam.  It is not much higher than stock.  I used  to have an Isky 262 with stock rockers.  It had approximately those lift values.

Just in case, you should try one out on an exhaust valve.    Or call Comp Cams - Yes it is a long way from Italy - 9-10 hours right?
 

Last edited by lowercasesteve (12/10/2019 5:15 PM)

I want to belive the stock rockers work without issues with compcam XE-256H.
Future check will be lifter condition and preload, pushrod (not bend) and rocker/stud interference.

...and I have also this question: are the stock lifter suitable for this camshaft?

Last edited by Marco (12/13/2019 8:27 AM)

right, new lifters were replaced when the cam was installed. But due I dont know how the oil pressure reach inside the lifter, I mean timing sequence, it must be always in pressure by the oil, or during the cam is rotating the lifter itself close the oil pressure during the stroke when necessary? I made a research in the web but not found anything, only a sectional view of the lifter with parts description but not a description of how it work in the general, not only about it  functionality.

Thank you, so it is only the check valve that allows the oil to pass.
Ok, I found oil onto the rocker, so the system properly work.