Rockers damaging pressed in studs

streetstang67 · Jun 7, 2005

After much research I decided on the comp XE256H cam (.477, .484 and 256,268). I was mainly tryin to decide whether to replace the springs and timing chain. I ended up changing neither . The other night one of my studs broke, its a good thing I was already planning on taking my heads to the machine shop for port/polish work. Of course I was kinda bummed about the stud breaking and just didn't pay attention to the others. The machine shop guy called me today to tell me that the current valve springs I have will bind with that cam, possibly explaining the damaged studs he noticed. He said the rockers were hitting them. Sounded like a good excuse to order some (proform aluminum) roller rockers . Anyway, do you think the studs will be alright, being not only pressed in, but also damaged? These misc. repairs are costing me and I don't really have the money to waste on extra machining and replacing if its not completely neccessary.

BigDaddyCee · Jun 7, 2005

Stock heads I would be careful with because of the pressed in studs. If you are using a non stock cams. Most performance applications call for a beefier head with screw in studs and guide plates etc. Usually it is a package deal if you beef up the cam then do the heads too.

D.Hearne · Jun 7, 2005

Especially with the Extreme Energy cams, you need screw in studs and guide plates, the fast ramps are hard on pressed in studs, even without the springs binding. Better give it up and get the studs done, otherwise you're going to be looking at more damage when the studs start popping out of the heads.

Boo Boo Foo · Jun 8, 2005

D.Hearne said:
Especially with the Extreme Energy cams, you need screw in studs and guide plates, the fast ramps are hard on pressed in studs, even without the springs binding. Better give it up and get the studs done, otherwise you're going to be looking at more damage when the studs start popping out of the heads.

Just as a follow up question to this rather important post, but is it possible to convert a '65 289 head with press-in studs to screw in studs via machining? And would it be possible to do without removing a head from the block?

Regards, Ive.

D.Hearne · Jun 8, 2005

Boo Boo Foo said:
Just as a follow up question to this rather important post, but is it possible to convert a '65 289 head with press-in studs to screw in studs via machining? And would it be possible to do without removing a head from the block?

Regards, Ive.

Yea, it's possible, but not a good idea to do it. You're likely to end up with studs that aren't straight plus the possibility of metal shavings in your engine. The head really needs to be removed and the machinework done on a mill to insure that all the studs are straight.

Pbum5 · Jun 8, 2005

Yup,
Since you have the heads off-
Screw in Studs and Guide plates are the way to go.

Loup-garou · Jun 8, 2005

D.Hearne said:
Yea, it's possible, but not a good idea to do it. You're likely to end up with studs that aren't straight plus the possibility of metal shavings in your engine. The head really needs to be removed and the machinework done on a mill to insure that all the studs are straight.

I've got a set of 289 heads that I got in trade, which were nicely cleaned up, but are missing the original pressed-in rocker studs. The previous owner was going to have the heads machined for screw-in studs, but ended up going with a set of '69 351W heads.

Can you recommend a machine shop in your area? So many of the guys I've dealt with in the New Orleans area know Chevy stuff, but are largely clueless when it comes to Blue Oval hardware. A few years ago, I caught my machinist bolting my 289 block to the boring bar with no torque plate installed - because he didn't have one to fit a Windsor block. At least he was willing to listen to reason (and my threats to not pay him another dime), and put my project aside until the torque plate arrived. He's deceased now, and his son (a MAJOR a-hole) was last seen running his dad's business straight into the ground.

Also, what's the correct amount of material that should be removed from the rocker pedestals? The measurements that I've seen often seem to refer to later heads with pedestal-mount rockers, which have different rocker pedestal dimensions than the early heads. Regardless of which machinist I go to, I'm going to have to bring a drawing and some numbers, so there's no screw-ups.

Any suggestions would be appreciated.

D.Hearne · Jun 8, 2005

Loup-garou said:
I've got a set of 289 heads that I got in trade, which were nicely cleaned up, but are missing the original pressed-in rocker studs. The previous owner was going to have the heads machined for screw-in studs, but ended up going with a set of '69 351W heads.

Can you recommend a machine shop in your area? So many of the guys I've dealt with in the New Orleans area know Chevy stuff, but are largely clueless when it comes to Blue Oval hardware. A few years ago, I caught my machinist bolting my 289 block to the boring bar with no torque plate installed - because he didn't have one to fit a Windsor block. At least he was willing to listen to reason (and my threats to not pay him another dime), and put my project aside until the torque plate arrived. He's deceased now, and his son (a MAJOR a-hole) was last seen running his dad's business straight into the ground.

Also, what's the correct amount of material that should be removed from the rocker pedestals? The measurements that I've seen often seem to refer to later heads with pedestal-mount rockers, which have different rocker pedestal dimensions than the early heads. Regardless of which machinist I go to, I'm going to have to bring a drawing and some numbers, so there's no screw-ups.

Any suggestions would be appreciated.

The guy I use for machine work like that is usually booked up several months in advance. The amount to remove from the pedestal for screw in studs and guide plates is .300" Any machinist that does Chevy heads for this can also do Ford small block heads, there's really no difference between the two as far as that goes, as long as the head is chucked in the machine with the studs perpendicular, the operation isn't any different, heads are heads.

Rockers damaging pressed in studs

streetstang67

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Boo Boo Foo

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Pbum5

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Loup-garou

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