496 Rocker Arm Stud
 

Guys,

During my cam swap, I discovered that the builder who rebuilt my engine last winter reused the TTY head bolts and, apparently didn’t use either enough or the right thread sealant, and I had a minor coolant leak, at least on a couple of the exterior head bolts. So I set myself to replacing them. I have a set of re-torqueable head bolts coming from Raylar. But I keep obsessing over the rocker arm geometry. ARP has rocker studs that would solve my rocker geometry issue, but they are 7/16-14 base threads. So now I’m considering pulling the heads, disassembling and tapping them accordingly. So….

Anybody ever drilled and tapped 496 iron heads for 7/16 stud base threads? Did you do it by hand? I can clearly see that they are on a compound angle. I have the tooling to tilt and orient them to “find” hole alignment. Then it would just be a matter of picking up each hole and making the chips. I’m just curious if there’s an easier way that is sufficient.

Thanks. Brad.

He re-used TTY bolts....wonder what process he used to 'tq' them.

You can drill/tap rocker studs but they should be on a machune of some sort to correctly align them.

Assuming your machine shop would be able to take care of that. A well setup dril press with angle capacity and proper rpm. Correct tooling. Maybe easier to just get them done after the capital costs for the tooling. One less issue you need to focus on.

But it is certainly possible. The multi angle BBC valves/studs make it a far more complex job than a SBC head.

Cyl Head machinery has the setup to align the angles required.

Tartilla,

No idea. It obviously worked. I don’t really know for sure, but looking back through our texts, makes it appear as though he did. Otherwise, the engine was running fine, coolant seep aside.

I AM the machine shop. It’s what I do for a living. I have the mill and a tilting table, and the knowledge base to do the work. I also agree that the precision is an important aspect. But I’ve also seen drilling/tapping guides/jigs that are used for this job to be done with a drill by hand. I just didn’t know if one existed for this head.

Thanks. Brad.

https://goodson.com/products/s-450-r...conversion-kit

Goodson is often overly expensive. You may find better rates from other cyl head tooling suppliers.

Your bolt holes are 10mm vs 3/8"?

Wouldn't it be easier and less risky to machine a set of custom M10 studs?

Tartilla,

I don’t need the tooling. We’ve got all that. I was hoping for a drill/tap guide that would save me a bunch of setup time on the mill. But, with the compound angle of the stud holes, that’s probably not a feasible prospect. Nothing worth doing is easy, I guess. :rolleyes:

Thanks. Brad.

Markus,

Been down this road. Aside from the fact that it’s always cheaper to buy than it is to make, the cold forming and rolled threads make ARP studs WAY stronger than what I would make, even if I got their metallurgy and heat treat perfect. The infuriating thing is that ARP has studs sitting on the shelf that would satisfy my needs, but they were from a “custom” run, and they want that same “custom” pricing for them they got from whoever ordered them to begin with, which is ~$800 for a set. Nope. Just farq that. As it is, they have studs in their normal inventory that will satisfy my needs, but they have 7/16 base threads. By far, the easiest route is to open up the holes in the heads for the larger threads and order studs. That’s what we call a “metal off” solution. Machining is what we do. This is just another Tuesday for us. Plus I get the bonus advantage of the considerably stronger base threads. Still chewing on the prospect, but I’m talking myself into it.

Thanks. Brad.

ARP makes a set of studs with the 10MM bottom threads.

https://arp-bolts.com/kits/arpkit-de...p?RecordID=393

Confused now
is or does the OP have the equipment to drill and tap the iron heads?
If so.. set up and do it.
If not
I agree the machine shop that does this relatively easy procedure once the gear is dailed in, is the way to go
heads are off, right
a bonus is at machine shop
They can bring head back to square if needed and check everything thing else
Yes its money spent
But as a mechanic...having right tools and expertise.
is a better route
However if those cost exceed the cost of a new head already done...its an easy go
drilling cast iron is not hard
Getting hole right and perfect...is what's important
following

BillK,

Maybe I should have just stuck with this thread…

I have that very set on my heads now. It’s the installed height that is the issue. When I establish “perfect” rocker geometry, I don’t like the thread engagement of the polylock nut. And that’s where this thread starts.

Thanks. Brad.

PowerBoatr,

Confusion is understandable at this point….

I have the machinery and the knowledge base to do the work. It’s just that compound angles are complicated and, without knowing what the angles actually are, it’s a matter of tweaking the setup until the existing hole is as close to perfectly aligned as possible for each bank of rockers, for both heads. It’s a lot of tedium. If there were an easier way to do this safely, I’d be all ears.

The heads are good. they were decked with the rebuild last winter. All I need are larger rocker stud holes. I should have done this during the rebuild.

Thanks. Brad.

understand
if you have the equipment and skill.
Bingo
I would practice on a nonservicable head.
i would think the info and math should be available

Sorry, I guess I didnt make the connection :) And yes, best to keep a subject all in one thread.
With that being said, when I do that job on other heads I do it in my seat and guide machine which makes it very easy to level the head for each angle.

That being said I would really have to wonder if you will have enough thread engagement for the 7/16 Studs ?? A 10mm bolt is .393" od. 7/16 bolt is .437" ? That sure does not leave much thread depth for the 7/16. That would worry me more than the number of threads you have on the polylock.

PowerBoatr,

I can do the math. It’s knowing the angles to do the math with that’s the issue. I have not been able to find that information out there anywhere. Just like the ignition timing, that is unobtanium information, near as I can tell.

I’m used to working on one-off stuff. I’ve been handed a $20K 3DP copper part and contracted to do finish machining on it. Scary as farq, but I do it. And this working WAY simpler than that was.

Thanks. Brad.

Maybe a friendly shop
could shed some light on angles
I would definitely get a sacrificial head to try it on
Good luck

BillK,

The concept of tearing the heads down was the furthest thing from my line, and I didn’t want to suddenly change the direction of conversation in the other thread, even being related as they are.

I’m not sure I’m following. The base threads will have the same 3/4” thread length. We’re just opening up the M10X1.5 holes to 7/16-14. The tap drill for the 7/16” thread is .368”, which will wipe out all but a minimal amount of the original M10 threads. The vast majority of the 7/16 threads will be in new, solid material. Larry at Raylar already asked me if I’d tapped them out for the 7/16 stud bases, so I’m guessing it’s not an uncommon thing. I have asked through email and will confirm before moving forward, however.

Thanks. Brad.

Sounds like others have done it but it sure does not sound like enough thread depth for me. I am seeing the tap drill size for 7/16 x 14 as 23/64 which is only .360" I know that does not sound like much difference but it would worry me. But if Raylar is doing it i guess its good to go.

I definitely would set it up in a machine over drilling it by hand if you have the equipment.

BillK,

I’m stuck with the thread depth, I think. I guess I could see if there is material below the stud to go deeper, but that would only be beneficial if there are studs available with longer base threads, and I’m not sure there are (haven't looked).

The good book says a “U” drill, which is .368”, for 7/16-14 tap drill. The general math rule is the basic thread diameter (.4375”) minus the thread pitch in distance (.0714”), which calculates to .366”, but I have no problem starting with a 25/64” (.359). The more material there is, even if it’s interrupted by what’s left of the M10 threads, the better.

I have emailed Larry about this, in specific, and will get confirmation before moving forward with anything.

Yup. I have the mill and a tilting table. It will just be a matter of finding the correct angle of tilt and rotation of the head on the tilting table to get the existing threads aligned with the spindle of the mill. I would (hopefully) be able to do, say, all the intake studs on one head, set up a set of stops to locate the clocking of the head on the table, then do the intake studs on the ohter head, then repeat the process for the exhaust studs. This should minimize the amount of time spend tapping the head around and tapping the tilting table, getting the existing tapped holes aligned with vertical.

As a side note, I just got a PM from Admin, informing me that I’ve received the “Community Builder’s” badge. I guess I’ve talked enough about doing stupid sh!t like this enough, they thought they’d give me an attaboy star to pin on my cape. :cool::rolleyes::Whatever:

Thanks. Brad.

Thats what is nice about having automotive tooling. I would put one of the existing studs in and use my valve guide level to get it level in the seat and guide machine. That plus having an air float table makes it a very quick process. I could probably drill and tap all of the intakes in less than 15 minutes. I cannot imagine trying to do it in a Bridgeport and having to indicate every single hole :(

Sounds like you have it under control !

BillK,

I’m running on the assumption that all the intake studs will be on the same angle, and all the exhaust studs will be on the same angle. Once I get one of them trammed in, and picked up the remaining three holes, it will only take a minute or two. Rinse and repeat for the remainder, four at a time.

But….

Since you mention that it is that easy, I will call my tuner, and see what their machine shop can do for me. I like doing these things for myself, but, as I said earlier, it’s always cheaper to buy than to make.

Thanks. Brad.

Is it done yet ? :kiss::p
Just poking fun. :wink

SB,

Stuck somewhere between scope creep and snowball. :picard1::faint2:

It’s gonna be a long winter.

Thanks. Brad.

Those pilots are not very long for a hand held solution in my opinion.

The hand held cutters for spring side guides remediation are suitable.

try being sidelined now 6 weeks, with broken foot
Boxes of stuff sitting on tool box ...that are for the liberator
still have 3 weeks until next x ray
at this rate. March i might get done , at least I broke the foot while in the boat

You are embarking on a path of time, think, set up
action, check and finish, and go.
I am eager to see how good it turns out.

The geometry isn`t perfect so you`re going to reinvent the wheel?
You over think wayyy too much buddy.

When I took off the valve covers for the first time after a season of running the Cig this is what I found.
Ran fine, anything better than this will be just fine, go find something else to do.:D



https://cimg8.ibsrv.net/gimg/www.off...67d6799cca.jpg

faaaaackkkk. Daaammm
All or just the one.
is it just camera angle or is rocker arm bent or twisted ...the high side on valve
the other side looks lower.
That would certainly give me the oh **** look

Just chuck one of the center studs in your mill and then tilt the table to the bottom of the head. Compound angle found. Just that easy

Snap,

https://cimg0.ibsrv.net/gimg/www.off...57f9d60b1.jpeg
https://cimg1.ibsrv.net/gimg/www.off...46f6646d3.jpeg

Pretty much what I did. First you rotate the head on the tilting table until it’s straight in the “X” axis, then tilt the tilting table until it’s straight in the “Y”. There was a bit more to it than that, but that’s the gist. We set up a “guide” against the intake side of the first head, then did either the intake or exhaust studs for both heads (can’t remember which we did first), holding the second head against the guide, eliminating the need to “find” the first angle, then rinse/repeat for the other set of studs. As is very typical with these sorts of projects, there was a lot of setup for not a lot of chip.

https://cimg1.ibsrv.net/gimg/www.off...eb682d0c6.jpeg
Turbulence ramp in the intake runner.

https://cimg2.ibsrv.net/gimg/www.off...6925c484c.jpeg
Gone.

https://cimg3.ibsrv.net/gimg/www.off...824992ddc.jpeg
Quarter sized flat surface facing incoming exhaust flow in exhaust runner.

https://cimg5.ibsrv.net/gimg/www.off...b5accadcf.jpeg
Streamlined. Probably could have done more here. Didn’t have the sack.

Per advice from Larry, Mr. Raylar himself, I decided to do some minor port work, while the heads were all dirty. Larry told me what to avoid. Also cleaned up any parting line flashing and general smoothing of the ports. No real material removal other than the obvious. Took them to the machine shop to be tank washed.

Got my Summit box today, with the new rocker studs and pushrods. I won’t get to play this weekend for reasons, so reassembly will start on Monday. Hopefully.

Thanks. Brad.

Dan,

My issue with rocker geometry was in the other direction; the rockers were tilted WAY back, to recover rocker nut thread engagement. The builder had even added a spacer under the studs to recover a couple threads.

Drilling and tapping the rocker stud holes in these heads is not a novel idea. It’s actually a fairly common modification among those who can’t afford the Raylar aluminum heads.

As it is now, I will have 7/16” bottom threads, with deeper engagement than the M10 bottom threads, almost double the rocker nut thread engagement, AND “perfect” rocker geometry, other than the roller being slightly off center on the valve step tip, front to back. I’m good side to side.

Thanks. Brad.

Hard to say how you'll fare without the ski jumps. The help bias the port flow and induce swirl...helping keep the fuel atomized and assist in healthy turbulence. It should increase the cfm a bit.

You can have too much swirl. Biased ports are often sufficient.

Have you back cut your intake valves 30°?

Helps with low lift flow..and getting the air moving earlier...allowing it to flow more on the larger valve opening phase.

Tartilla,

Larry tells me they are primarily for automotive applications, to improve efficiency at lower RPMs. This engine was OEM designed to spend its life at 1700 RPM. We NEVER run 1700 RPM, other than sweeping through it, getting on or coming off plane.

I didn’t do the valve job. Given the builder primarily does high HP marine engines, I have to assume he did the valves properly for the application. And, to be honest, I haven’t really looked at the valves, as I wouldn’t know what I’m looking for.

Thanks. Brad.

Guys,

https://cimg2.ibsrv.net/gimg/www.off...2af31886b.jpeg

Fun fact…. Guide plates are hardened. I wasn’t expecting that. I had to buy a 7/16” carbide reamer to open them up for the new rocker studs. Slow and easy, and lots of MolyDee cutting oil, and they cut like butter. Seemed to hold location pretty well, too.

Coming together.

Thanks. Brad.

[QUOTE=Brad Christy;4939648]Tartilla,


I didn’t do the valve job. Given the builder primarily does high HP marine engines, I have to assume he did the valves properly for the application. And, to be honest, I haven’t really looked at the valves, as I wouldn’t know what I’m looking for.

Beware....We would assume that HP engine guys with 30 years experiance would do things right, WRONG. I had 2 sets of AFR heads done with welding up corrosion and new seats. Dyno'ed and one engine was off 200hp from the other. Told that the one engine had serious leak-down in several cylinders. Ordered new AFR 385's and had them on order for 4 months so no engines this past summer. The valve job was so bad with bad margines and not seating due to warped seats, valves ground off center, the heads are SCRAP. I will never use that guy again! Not funny but he runs a very conpetitive Pro-Mod 950 cu/in plus car. Guess there is no care in good customers engines by some and it showed.

[QUOTE=LakeBoat4;4939805]LakeBoat,

I’ve actually since come to find out my builder didn’t actually do the heads. He sent them to the same shop my tuner’s family owns. The tuner does the automotive repair work and tuning, while the dad does the machine work and builds the engines. They are fairly widely known for building strong engines. Compression seemed strong all summer.

https://cimg0.ibsrv.net/gimg/www.off...aa7fd556c.jpeg


Thanks Brad.

Guys,

Got one head torqued down and did some preliminary rocker sweep checks.

Exhaust
https://cimg0.ibsrv.net/gimg/www.off...ef8f0dfb2.jpeg
On the base circle

https://cimg1.ibsrv.net/gimg/www.off...a9ca68545.jpeg
Mid sweep

https://cimg2.ibsrv.net/gimg/www.off...366a94a71.jpeg
Full open

https://cimg3.ibsrv.net/gimg/www.off...5d4af8ce1.jpeg
Well centered

Intake
https://cimg6.ibsrv.net/gimg/www.off...70f1e1c6c.jpeg
On the base circle

https://cimg7.ibsrv.net/gimg/www.off...1b7e65b86.jpeg
Mid sweep

https://cimg8.ibsrv.net/gimg/www.off...2cd1827e3.jpeg
Full open

https://cimg9.ibsrv.net/gimg/www.off...13aaad7bf.jpeg
Well centered

I’m pretty happy with the decision to drill and tap for the larger rocker studs. I’ve got probably double the base thread engagement, probably ten threads of engagement with the rocker nut after preload, and just about perfect rocker geometry, not being perfectly centered on the valve stem tip aside.

Thanks. Brad.

So, in hindsight, was it worth the effort compared to paying $800 (?) for the custom M10 studs?

Markus,

I didn't pay $800 for custom studs. I'm sure those were for someone in my position that was unwilling, or unable, to modify their heads. That was the whole point behind drilling and tapping the heads for 7/16" base thread studs; to get away from the need for their "specials". These studs are an on-the-shelf existing part number that worked for my setup. As it happens, the studs I opted for only come in sets of 8, so I had to buy two sets, but they were less than $100 a set. Studs, pushrods and new valve seals were a combined total of less than $400, including shipping. Plus, it was fun, trying to Frankenstein it all together. Absolutely worth it in my eyes.

Thanks. Brad.

Owning a machine shop help just a tiny bit,,,,LOL.

Wildman,

At least a bit, yes.

Thanks. Brad.

machine shop??
by the sneaky backgrounds in the pictures
its a full blown. " let's get it done" shop
you have the set up
those rockers being centered.. sooo much better than before
👍