Need some help with my vortec heads. I want to change the current springs to PAC 1218 springs (beehive) When I pulled the rockers the valve tip had wear marks where the rocker was rolling. This leads me to beleive the tips are not hardened. The valves were not rotating. The heads are cut for 986 springs. The current springs are unknown and the retainers are a deep dish that gives 1.900 installed height with no shims and .600 retainer to guide clearance with the seals installed.
To fix the valve tip issue I think I need to put lash caps on. This will require going to a 10 degree lock. So the 787 retainers are out. What is the installed height on 795 retainers with respect to stock vortec (+.050, or stock)? The current valve are +.100 I believe. I would like to get an idea of the installed height prior to ordering. If I can get the height of 795 retainers with respect to stock then I can add to a measured value using stock retainers and locks.

Thanks in advance

John

 

I couldn't help you out here, you're running a 32V DOHC, not simple old pushrods!

 

Shadow didn't read very closely.
To be having 1.9", you may have a set of +.100"-long valves in there. This is worse than it seems, for 2 reasons. First, it really screws up the valvetrain geometry, and second, you should NOT run more than 0.480" intake valve lift with these heads, even if you do have clearance, so longer valves aren't even helpful.
Start by pulling the valves, and measuring the OAL.

 

Will do on measuring the valves.

Can you explain more about the .480? I am currently running XR270 with .495. What is the issue with this?

Would the geometry be corrected by installing a correct length pushrod. My plan was to measure for correct pushrod length when I got the springs and new rockers on. The wear marks on the valve tip have the right pattern and are centered. I am just concerned about the fact that there are wear marks on a low time engine.

Thanks

John

 

I'm getting very tired of re-typing this. The intake ports stall above 0.475" lift. At 0.475", getting 238 cfm is expected. Go to 0.485", it'll drop by at least 10 cfm, because of turbulence. But as you close the valve back towards 0.470", flow does not go back up. You have to close the valve nearly half way fefore flow recovers.
If you're using hydraulic lifters, whether flat or roller, then a rated 0.480" will deliver no more than a real 0.476". That's good.

 

Thanks for replying. I have searched a lot lately but mostly around valve springs. I appologize for making you repeat yourself.
Right now I am trying to get rid of things like the small valve springs of unknown origin. The previous owner could not tell me what they are so I would like to change them for ones I know what are. While I am in there I will be replacing rockers with rollers and verifying the pushrod length for proper geometry. I want to make sure I understand everything that is required before I begin buying parts I would like to use the ultra promagnums with 7/16 stud but I need to make sure that I order the right length stud, and that the geometry will work out with the correct pushrod. I had forgotten how much stuff needs to be custom fitted.

Thanks

John

 

It's called sarcasm, look at his user name........

 

If you have the 7/16 studs, great. But otherwise, they really aren't helpful. Unless you're doing something really uncommon, these heads just won't support the RPM necessary to need those. And if you are going for big RPM, then get AFR heads, not these.
Alternately, the other reason for stiff springs, which is what big studs are for, is big boost. Again, wrong heads for the application. Decks are too thin, chambers are too small, exhaust flow sucks even maximum ported with big valves.
There's nothing a Vortec head is right for, which requires over 300 pounds open, and that doesn't require changing from the pressed studs.