Vortec Head Modification/Upgrade

[FreeBeeTony]

rocker arm geometry and valve stem seals are unrelated.

Not sure you understand the nature of my project.

 

[aimlow]

Valve stem seals are inside the spring. Spring is retained by keepers and retainers. This is a fixed distance, adjusted by valve spring shims to get the correct assembled spring height. Caps are used to compensate for wear/machining on valve stem ends. The performance trend is to let intake valve heads to stand proud in the combustion chamber, and recess exhausts valves so they exhaust valve does not shroud the incoming charge.

In any case, the deeper the valve sits in the seat, the less need there is for caps. As the engine runs, the seats/valve faces wear slightly, and the valve sits even higher in the guide, further reducing the need for caps.

 

[scoflaw]

He's cutting the head to increase this "fixed distance", so he can get more cam lift, has nothing to do with valve seals. Adjusting rocker arm geometry comes after.

 

[aimlow]

He's cutting the head to increase this "fixed distance", so he can get more cam lift, has nothing to do with valve seals. Adjusting rocker arm geometry comes after.

Cutting a valve seat should have no affect on rocker geometry. Certainly cam profile/lift will, but to arbitrarily install lash caps is a bit premature.

Actual valve lift is a function of not only cam profile, but rocker arm and rocker arm geometry.

 

[scoflaw]

Actual valve lift is a function of not only cam profile, but rocker arm and rocker arm geometry.

Disagree with this...Rocker ratio yes, The geometry part is to get the valve guides to live, nothing to do with lift

 

[FreeBeeTony]

to arbitrarily install lash caps is a bit premature.

As illustrated in the pics in post #60; I am not going to install lash caps.
I will need to cut (reduce the height) of the valve guide boss. This is the curse (or part of the curse) of the Vortec heads.
By changing the springs, the distance between the retainers and the valve seals hasn't changed. I believe if you use the beehive springs it may not be necessary to cut the valve guide boss.......If I knew that earlier I may have gone that route.

I wanted a winter project and I got one!! I still enjoy turning a wrench and learning!

 

[aimlow]

Disagree with this...Rocker ratio yes, The geometry part is to get the valve guides to live, nothing to do with lift

Oh yes it does. In the class we raced in, we could pick up 10% lift by optimizing geometry. Street use, wear is important, especially with as much lift as this cam has.

 

[aimlow]

As illustrated in the pics in post #60; I am not going to install lash caps.
I will need to cut (reduce the height) of the valve guide boss. This is the curse (or part of the curse) of the Vortec heads.
By changing the springs, the distance between the retainers and the valve seals hasn't changed. I believe if you use the beehive springs it may not be necessary to cut the valve guide boss.......If I knew that earlier I may have gone that route.

I wanted a winter project and I got one!! I still enjoy turning a wrench and learning!

I believe you are correct. all I've done is use stock vortec heads and components...never got into parts swapping. Is the guide iron or bronze?

 

[FreeBeeTony]

Started disassembling the engine in the boat today, removed the intake and the head that has the broken rocker stud.
Plan on doing a bit of investigating before I tear it down; going to test for max lift using the method pictured above. Will post pics as I go.

 

[FreeBeeTony]

Tested for coil bind........didn't look too good; similar to what I saw in the boat.
Removed a spring on an intake and exhaust valve; to my surprise my machinist did cut down the valve guide boss (see pic); but I will still need to machine the seats for the new springs (other pic). Also included is a pic of the spring that was installed. Any way to determine what spring it is? I saw something online about springs from LS1 engines being used on vortecs. these have some red paint on them.

 

[FreeBeeTony]

Don't cut too deep and get into a water jacket.

How deep is too deep?
When looking at the heads that were modified by my machine shop, it looks like he already cut the pockets ~ 0.100.
Is that too deep? I'm now going to have to add shims to make an acceptable installed height on my new springs!

 

[Scott Danforth]

Tony, you cut the heads until you get to the correct installed height, and maybe .030 more to use shims.

 

[FreeBeeTony]

Hi Scott, my point/question is: when I checked the installed height on the "practice head" after I machined the valve guide boss w/o going any deeper than necessary, the installed height was good. Now when machining the heads from the engine in the boat that the machine shop "modified" it appears he already machined the pocket 0.100 which now requires me to add shims. I really just want to make sure that 0.100 was not too much. I plan on adding a 0.060 shim to bring me into tolerance for the springs I purchased.

Hope that made sense!

 

[achris]

Why did the machine shop machine deeper than you specified?

 

[FreeBeeTony]

Hi Chris............
I didn't specify the original modification made by the machine shop.
I told him the lift of the cam and he said he had a set of springs that would work, I didn't think he did any machining being that he installed beehive springs. I know ALOT more now than I did then about lift/clearance/coil bind!!

 

[Lou C]

So Tony is what you are saying is that the machine shop did cut the spring seats but used the wrong springs based on the camshaft lift leading to the coil bind? And if you use the correct springs no machining may be necessary at all in fact you need to use shims to get the height correct?

 

[Scott Danforth]

Lou, that is what it sounds like to me

 

[FreeBeeTony]

Yes Scott, Lou summed it up very well.
I do need to machine/cut the spring seat for the inner spring diameter, but not the depth.
Lou, you made it sound so simple.........I seemed to have trouble describing it!

 

[Lou C]

And it seems as if the trouble you had could have been avoided if only the machine shop instructed you to check for coil bind before running the engine. At that point then the issue could have been dealt with by changing the springs and using shims if needed. Well live & learn!

 

[FreeBeeTony]

I think he should have checked for coil bind being he knew the lift of the cam............
That's why I like to do things myself..........if I have the ability!