Converting stock pedestal mount heads to stud-mount

cgrey8 · Post by **cgrey8** » Sat Jan 24, 2009 9:18 pm

What's required to convert stock heads to use stud mount rockers? I know you can buy rockers for pedestal or stud mount. But if I'm going to invest in roller rockers, I'd want the option to use them on an upgraded head in the future vs buying pedestal mount rockers that would likely only work on stock heads.

My initial thought is it's simply screwing in studs and that's it. But I wanted to ask just to be sure its this simple OR if there's some "gotchas" I should be aware of related to this.

Thoughts?

usmcrp1044 · Post by **usmcrp1044** » Sat Jan 24, 2009 9:45 pm

I was considering doing this when I had my heads done. Only problem was, I couldnt find one god damn person who knew the answer. I called Jegs, I called Comp Cams, I called Crane Cams, I could find nobody that knew.

So finally, I called a local fly by night machine shop to dig some answers out of them. According to them, usually just the bosses have to be drilled in the existing holes to whatever size stud that you are using. Sometimes the boss actually has to be milled down. I was told that it just has to be at the same height. With a stud though, you have a certain amount of room up and down to set the rocker, so I believe that you could just drill and tap the existing bosses that the pedestal rocker thing screws into, and that should work.

But then again, I'm not a machinist so dont listen to a word I say.

Dave · Post by **Dave** » Sun Jan 25, 2009 6:56 am

Why not just buy the upgraded heads made for the pedistal rockers? I don't know who all makes them other than AFR but them are some good heads. Think that maybe the GT-40's would be. See now that Edlebrock has the pedistal heads also.

Dave - The are also smog legal

165cc SBF Street Head Part Numbers
CNC Ported Pairs of Heads Complete With Parts or Ready to Install

CNC Street Ported Cylinder Heads
Description Part Number
165cc Street Heads, Stud, 58cc 1402*
165cc Street Heads, Pedestal, 60cc 1472*
CNC Competition Package Street Porting
Description Part Number
165cc Street Heads, Stud, 58cc 1404
Stage 1- Bare Heads No Porting or Parts
Description Part Number
140cc Street Heads, Stud, 55cc 140*
140cc Street Heads, Pedestal, 55cc 147*

Dave · Post by **Dave** » Sun Jan 25, 2009 8:23 am

The smallest stud has a 3/8" thread. You would have to drill out the pedistal guide another 1/16" to get the stud to work. Think you would be getting pretty thin in this area below, about .045". I think that the pedistal type might actually be a more stable way of guiding the rockers arms rather than using guide plates.
Dave

usmcrp1044 · Post by **usmcrp1044** » Sun Jan 25, 2009 1:53 pm

Oh yeah, almost forgot all about it. If you do switch to a stud mounted rocker arm, you need guide plates. The guide plates stop the pushrod from moving left and right. With the pedestal type, the bottom of the rocker is square, and goes into the other square part. This prevents the movement of the rocker and therefore the pushrod.

Without guide plates, the rocker arm will move and slip off the valve and have bad consequences. Some heads had a small hole for the pushrod to come through, and didnt require guide plates. I believe that most manufacturer's did away with that years ago, but I know an old set of 289 heads I had were like that. If you have pedestal mount rockers, I'm almost positive that your heads wouldnt be like that, because I was told it would cause everything to bind up.

And the only factor that would determine how far you have to drill would be the depth that the stud is supposed to sit at right?

Dave · Post by **Dave** » Sun Jan 25, 2009 3:01 pm

Yep the real early 289's had the small hole. I'm setting up my new heads so I have all these pictiures I can take right now. Another big problem would be finding a stud long enough. I don't have a pedistal roller right here but have the stock Explorer to compare. the stud mounted rockers have that big adjusting/locking nut. Not sure they even make a stud that would work. Don't think there is anyway to convert one to the other.
Dave

Foxracin · Post by **Foxracin** » Sun Jan 25, 2009 6:27 pm

http://store.summitracing.com/partdetai ... toview=sku

Will not be as strong as getting the heads machined to accept regular studs but the price is not to bad and it will probably cost a few pennys to get the heads machined and you would have to find somebody that knows what there doing to get the geometry right.

These kit require no machining. They have a 7/16 and 3/8 stud size.

Dave · Post by **Dave** » Sun Jan 25, 2009 6:39 pm

There is so much out there I'm sure learning and I hope it never quits.
Thanks for the update.
Dave