496 Roller Rocker Studs
 

Guys,

Y'all's gonna think I'm nutz....

During our 496 build, it has become apparent that ARP rocker studs for the 496 are made with the OEM stamped rocker arms in mind, and, with roller rockers (at least the Scorpions), they are more than a little shorter than the builder and I would like, leaving only about 1/4" of thread engagement for the polylock nut, if that. Industry standard for fasteners is typically ~1.5X the thread diameter, and we are looking at barely .5X. I called ARP, and they have some on the shelf, .150" longer than part number spec, but, due to them being from a previous "custom run", they want $55 each for them That's $880, for those slow with the math, which is almost double the cost of the rockers. If I were to do this, added to the cost I've already got in the rockers, I'm only a couple hundred shy of the cost of a set of T&D shaft rockers, which is obviously a non-starter, as much as I'd love to go that route.

So...

I'm looking at the prospect of making some rocker studs, specifically for 496 roller rocker applications. The machine work is easy; it's a stupid simple part. I would intend to use the same material ARP uses, and my heat treat shop ensures me they can achieve the tensile strength specs ARP advertises. I would also intend to have the threads rolled after heat treat, just as ARP does, as this is a large part of their tensile strength achievement. Hell, it's probably the same thread rolling vendor ARP uses. My guess is I am going to be presented with a QTY incentive on the thread rolling. So, I could end up making a batch of them. Surely, there have been others encounter this same conundrum...? Maybe I could solve others' problems while I solve my own...? Any market?

Thanks. Brad.

Do you have a different brand rocker arm that you can try ?

I'd buy a longer off the shelf from ARP or Manley or whoever and cut them down. There are other manufacturers of rocker studs.

The problem with that on the 496 heads is the small 10mm hole that the studs thread into.

Brad,
Another option would be to put 7/16 timeserts in the bosses and then you can use any "normal" 7/16 stud. A lot cheaper than making custom studs.

Gotcha, I drilled and tapped out my old 3/8" heads to 7/16" before.
Correction. My head guy did the work. Probably inserted it.

Rookie,

You'd think. But the M10X1.5 base thread seems to be unobtanioum from anybody but ARP. At least as far as I can see at Summit. They have two options: The ones they offer for the 496, which are "too short", and the ones they offer for the 4.3Vortec, which are even shorter yet.

I'm not afraid to make them. ARP was gracious enough to share their material spec and tensile strength achievement online. This isn't voodoo. These things aren't coming out of a boiling cauldron, stirred by witches. I can make them on any given day of the week, and I have a world class heat treat shop right in my proverbial back yard.

I'm just wondering if anybody else has ever encountered this issue and wished someone offered a solution...

Thanks. Brad.

Bill, Rookie,

If only I'd known about this while the heads were being done. :picard1:

Thansk. Brad.

Maybe reach out to Raylar and see if they have something that would work?

your intake on yet.pull the heads and have the machine shop put the 7/16" threads in and buy the proper studs.I've converted a few 496 heads.
what size cam are you running?

good point

Xlint,

Spoke with Larry. All he had for me was advice to abandon the 1.8 ratio rockers and an offer for his rockers.

Thanks. Brad.

Sutphen,

Don’t tempt me. Hell, I could open up the holes myself. I’ve got all the tooling and hardware that would be required. I could even open them to 1/2-13, which ARP has an option for that is plenty tall enough, or install HeliCoils for 7/16-14, and take advantage of an opportunity to move them away from the valves a bit, as the builder is not totally happy with where the roller tip is. As of right now, he is working out some shorter pushrods that will tilt the rockers away from the valves and move the roller tip where he wants it.

We are retaining the OEM cam. The .510” lift theoretically becomes .540” lift with the 1.8 ratio rockers.

Thanks. Brad.

No need to reinvent the wheel. Tap them out to 7/16-14 and screw in some off the shelf studs.

Snap,

It would seem to me that regular Joes having an off the shelf option for what I can't imagine is a totally unique situation would be less reinvention of the wheel than having to modify heads.

What I'm considering doing would provide do-it-yourselfers a credit card option for a roller rocker upgrade.

But, maybe, I am the first person.... ever.... to try and install roller rockers on OEM 8.1 Vortec heads and actually see the polylock thread engagement as a potential point of failure. Who knows....

For the record... I have no issue with tapping the heads for larger base thread rocker studs. I have that capacity, too, and it would, by far, be the easiest route. And, as I said previously, this would provide the opportunity to move the stud slightly away from the valve, improving contact centering of the roller on the valve tip.

Thanks. Brad.

You can buy longer polylocks to have better thread engagement. My buddy did that on his this past summer when he changed from the factory rockers to 1.7 roller rockers. Originally his didn't have much thread engagement either and he didn't like it. I don't remember who manufactured them but they weren't that expensive.

CDail,

The issue isn’t the length of the polylock. It’s that the studs don’t extend enough above the rocker trunnion at proper rocker geometry. If anything, the polylocks couple probably be shorter.

Thanks.

Guys,

From the looks of it, this was likely a non-starter out of the gate. I've gotten two no-quotes and a ridonkulous quote from a third vendor on the thread rolling. It would be far cheaper for me to use the "customs" ARP has on the shelf. I suspected this would be the case for the QTYs I asked for (two sets of 16), but it was worth the ask.

Carry on....

Thanks. Brad.

This is the better route...tapping for a 7/16" stud. Your method of fabricarion, though courageous and worthy etc...you still end up with a 3/8" sized rocker stud...far less than optimal.

Same issue with the 088 head non-adjustable racker systems. 3/8" studs into the head. Drill/tap is the best method.

BTW...ARPs price on those seem a little steep, despite the custom work.

ARP makes a conversion stud for those. I have used them several times with fairly high spring pressures and have not had a problem.

Tartilla,

My hope was to try and help those who didn’t have the readily available option to do the machine work. The M10 threaded stud they offer is plenty strong enough for most applications involving the stock 496 heads. I would think most who are getting into valve springs that might challenge the limits of the M10 threaded stud would have abandoned the stock heads prior.

Yes. I totally agree on the price being egregious. I mean, I would probably charge more for the QTY I inquired about, but I’m not a bespoke MFR, dedicated to a specific product like ARP is. The change I was asking for would involve a simply programming change, and the parts could have risen along through the rest of the operations (heat treat, thread rolling, black oxide, etc…). I expected a small premium for them, but good GOD…. My guess is they’ll sit on the shelf forever. I can’t imagine being so desperate for a solution that someone was actually willing to pay that for them initially.

Thanks. Brad.

I haven’t posted enough to post pics yet of how I did my 496 but I used arp studs with comp 1.7 rockers and ran into similar geometry issues with pushrod length and thread depth of the poly locks. I think I used a washer under the arp conversion stud and a shorter pushrod like drag racer art was stating. 1.8 can’t be too big of a jump to be compensated by pushrods but I’m a hobbyist builder at best. If I had the knowledge or tooling to make it 7/16 I’d go that route, I was in a rush and eager to get my engine done and in as it was already mid June when I got the block back

Buona,

What kind of spring pressure do you have? The builder and I discussed the possibility of spacing up the stud, but we both agreed it was only sacrificing one thread engagement for the other, and a net loss of overall strength.

I haven’t seen the stack up with the shorter pushrods yet, but the builder is confident the proper length pushrods will pretty much solve the issue. He says once the lifter is preloaded, the polylock will pulls down a fair bit further and he’ll be happy with the thread engagement.

As for the rocker ratio, the 1.8 vs 1.7 ratio shouldn’t make any difference. It’s the conversion from stamped rockers to roller that has made the difference in geometry. As a proverbial MFR of aftermarket parts, I would do everything I could to ensure the end user could do a simple part for part swap, upgraded rocket studs aside, but I’m assuming that’s not in the engineering cards.

Thanks. Brad.

They were a comp cams dual spring. Needed some machining and different locator on the bottom to get rid of the stock rotator plate. Pretty sure I pieced it together from raylars book and my engine builder that did the heads. Originally ran prw 1.73 rockers but had a failure on my part due to not checking pushrod length. Went with comp 1.7 this go round. Correct length pushrod did solve all the issues and eliminated the spacers I looked back at some pics

After going stud adjustable (from fixed bolt down stud style) I would expect proper geometry would need custom length pushrods.

Tartilla,

The mounting method hasn't changed. OEM is an adjustable stud, and that has not changed with the upgrade to roller rockers. What has changed is the geometry of the rocker itself. They just don't sit like stamped rockers do. In my naivete, I assumed that they would be a drop-in replacement, and didn't realize that they can't be, given the plethora of options that have to be accounted for, like cam base circle, deck/head machining, spring selection, etc.... So, when the builder indicated new pushrods were necessary, I assumed it was the same "496 white elephant" issue, where parts just don't work for the 496, and modifications would have to be made to Frankenstein it all together. I still think, at the end of the day, taller studs would be beneficial, but certainly not a necessity with the spring pressure we are using, compared against the amount of cost and/or work involved in making that happen. The pushrods have been ordered, but I don't know if they have been delivered or installed. I'm sure I'll get an update when they are.

Thanks. Brad.

OEM is not an adjustable stud, rocker nuts are torqued 20-22 lbs

My bad on the poor comms. I'm fighting the same issue on my 088 heads. I can see where GM went with the non-adjustable rocker system...TQ and forget. But any block decking/head machining or head gasket changes would put the rocker geometry off. I'll prob just get the Comp 3/8" to 7/16" studs...for the 088 heads. Mycams are pretty mild, amd I don't plan on having the Iron heads for long.

How is the budget making out 85% of the way in?

Tartilla,

I'm kinda regretting not pulling the heads and tapping them for 7/16-14 studs, just because. But, like you, the cam is really mild and the spring pressure, even though it's way better than OEM, is still not overly heavy.

Trying not to look at it the bill too much. I'm still pretty confident we're going to slide in under $10K, but there's probably a lot of nickel-dime stuff that is going to add up. I'd hate to think what the bill would have been had I just packed it into someone's shop and told them to call me when it was done. I know I've spent a fair bit through the company, disguised as "work", that the CFO isn't going to be made aware of. I'll get a tally at some point.

Thanks. Brad.

BoatNT,

My bad. I didn't realize that. In the absence of me seeing the heads in OEM assembly condition prior to disassembly, I saw a lack of pedestal in the stack-up and assumed. I'm really out of my element with most of this stuff, and most of the process has been a steady stream of filling in the blanks on my end.

Thanks. Brad.