??? c9ve-a heads rocker arms

these heads have screw in studs from factory are they adjustable or not

Yes the factory studs are screw in, but no they are not adjustable.

i was told i could use chevy screw in studs is this correct

I'd use a stud with the 1.90" effective lenght, base thread would be 7/16-14, and top thread 7/16-20. The std. BBC stud usually has an effective lenght of 1.75". You will need some lock nuts or poly locks. Finally chase the threads in the head with a 7/16-14 bottoming tap.

Keep in mind what rocker you use, if you are using guide plates, if you cut the pads down to compensate for the thickness of the guide plates, and what pushrod lenght is needed all can affect what lenght stud will work.

Steve

thanks for all knowledge about this how big of a lift can i run with the factory rockers my cam is 543in 574ex thanks

74f100 wrote:thanks for all knowledge about this how big of a lift can i run with the factory rockers my cam is 543in 574ex thanks

Using straight shank Big Block Chevy studs and nuts will allow your stock OEM rocker arms to become adjustable. I would suggest using poly lock type lock -nuts instead of the prevailing torque nuts though.

The threads in the head will need to be "bottom tapped".

74f100 wrote:thanks for all knowledge about this how big of a lift can i run with the factory rockers my cam is 543in 574ex thanks

I would not use the factory rail rockers with that much lift. You run the risk of the rails contacting the keepers and resulting in a dropped valve.

You also should get the valve guide ends cut down and also machined for a PC type seal as you are not going to have enough clearance otherwise.

Steve

thanks guys

hey steve what can i do with these heads to have adjustable rockers with out having to machine
the heads for guide plates do you have to cut the head down to run guide plates

A lot of guys just add the guide plates, hardened pushrods, screw in studs, roller rockers, and poly locks. The main issues are the guide plates are a bit higher than they should be which may result in the rocker tip being not centered side to side on the valve stem. Just have to mock it up and see if it is acceptable. Also have to check that the rocker clears the stud at the base.

If you want to do it the right way you would cut the mounting pads down about .220" (that is assuming they have never been cut before).

thanks i may just have to do that got to much money in it to take a chance

Just need to correct amount to mill is about .110" and chamfer the hole to make sure the stud seats properly.