Plating studs

[khamul02]

There are so many little studs on this engine that are kinda ratty. Some have worn threads and need to be replaced.. some are fine and just need plating. There was one I put a dye on and it seems fine now. it's a collection of chaos.

Is there any reason not to put certain studs to replace/replate? I have pulled all of the cam housing studs out without issue. I have a set of cheap threaded stud puller/installers and it is working fine so far. But I don't want to do anything I should leave to the pros, because I'm totally a noob. ;-)

[Flat6pac]

But you won’t pull the ones on the heads facing the cam carrier
The ones you pulled should be no more than the couple threads outside the nyloc, the rest of the stud I’d inside and generally look like new.
Bruce

[khamul02]

Bruce, that was the before picture. All of the cam studs are out now on one side but one. It was a little tough so I'm soaking it in some lube for 24 hrs.

Should they not have come out easily? I still have a few more to do on the other side.




Are there other studs in the case I should leave alone?

[Dpmulvan]

Don’t bother soaking them, hit them with propane or map gas for 30 seconds they’ll come right out.

[Neven911]

I've just done the same and yes some needed some heat to loosen. Are you going to pull out the spraybar? you can also pop out the cam end plug and plate that as well
Watch this https://www.youtube.com/watch?v=r8qzvnoSEog&list=PLkWFofpgz2OgdnVCiMm4834QmoZydBqps&index=1&t=1276s
Though he doesn't remove the studs

[khamul02]

I have watched everything that dude has put up! I was curious about those ends and getting them replated but spray bar looks like stainless or aluminum.. so I wasn't going to bother with it.. I was going to let the machinist deal with it.

Are there any studs on this thing that I shouldn't attempt to pull on my own for replating?

[Neven911]

I'd be careful pulling any studs out of magnesium unless you have an oven to heat the item up and break down threadlockers, very easy to destroy a thread (speaking from experience here)
I'm having all my studs, nuts etc nickel plated, I'm told it's better than zinc as it is not sacrificial and will last longer

[khamul02]

It's an 80's so hopefully the aluminum will hold up better when pulling all of these things out.
I have seen companies selling stainless studs. I wonder if there are any downsides to using stainless hardware?

[KTL]

Nothing wrong with re-plating the studs on the cam housings because they're not under any considerable load. They're just sealing the valve covers. Basically all of the hardware in the cam housing can be plated with no concerns- studs, banjo fittings, spray bar "setting" plug are all fair game.

The cam end plug Neven911 is referring to is the steel "freeze" plug in the end of the camshaft housing bore (where the camshaft itself resides). He's not referring to plating the actual spray bar bore plug, which is indeed aluminum and so is the spray bar aluminum.

The steel plugs do tend to rust and sometimes can be a bit stubborn to knock out because they're a moderate press fit and also sealed around the perimeter with a thin coat of the famous orange Loctite 574 goop. I'd be cautious about reusing them if you have to knock them out hard. The center can deform a little bit and you can also lose a little bit of the "bite" in the plug diameter from years of the steel relaxing its shape. Notice how easily he taps in the new steel plug in the video. That's not to say that new plugs should require a ton of force to drive in place. I'm just saying that a reused plug sometimes won't go back in as tight as it came out. The steel is mild stamped steel, not spring steel, so it's not difficult to deform. They're cheap to replace and therefore I feel it's wise to just buy a couple of new steel plugs.

I would suggest only removing the spray bar end plugs to get a look inside for any crud that should be removed. Leave the spray bar in place and clean it in-situ. The reason I say that is because the spray bar is sealed to the housing at the factory to ensure there's no leakage at the locations where it feeds oil to the camshaft journals/bores. So don't disturb the seal if you don't really need to. Because when you remove the spray bar, it takes a bit of patience and care to not damage the end and scrape the heck out of it as it's coming out. After doing a number of these myself, I tend to think the factory assembly process heated up the cam housing to expand it and then the "cold" spray bar was inserted to go in nice and easy. Because when you do a cold removal, the spray bar comes out with some significant resistance.

When you watch him reinstall the spray bar in the video, notice how easy it goes in. He cleaned the spray bar exterior and also ran the brush through the cam housing to clear any debris. Doing that loosens the fit of the spray bar in the housing, and thus the oil feed (oil pressure, mind you) to the cam bearings. This is why I say leave the spray bar alone if it looks OK in place. You can look down the spray bar interior with a bright light and see if there's any crap in there while it's in the housing. Note that since the holes in the spray bar are drilled, it's always going to look like there's something in there on account of the rough edges created by the drilling. This is why his method of running the brass brush through the spray bar while it's in the housing is good practice. The brush can knock loose some of that "flash" material. However, after brush cleaning, use some brake cleaner and a piece of stiff wire to clear all of the pin holes and cam bearing holes to ensure any loose material caused by brushing is removed.

I wouldn't recommend stainless studs. Stainless and aluminum don't agree with each other. The dissimilar metals induce galvanic corrosion and you end up with studs frozen into the housing for the next person to deal with. The reason is because aluminum and stainless steel have anodic indices that are somewhat far apart on the scale of materials (see listing of metals in link below)

https://en.wikipedia.org/wiki/Galvanic_corrosion

Stainless steel isn't identified on the list but it's basically chromium steel. So the aluminum corrodes more easily when in contact with stainless steel. This is why the steel studs are plated with zinc or cadmium because the coating brings the anodic indices closer together at the bottom of the list. The plating on the studs is also to protect the studs themselves, regardless of what material they're installed in. Zinc or cadmium is basically a sacrificial coating. At least that's how I understand it.

[khamul02]

Kevin,
Huge thanks for all of the info. I actually was reading a few older posts about stainless and plan on avoiding it and just going with the replate. I will take your advice and buy new plugs as I knocked the crap out of them to get them out. I don't see damage but who knows.

I think the spray bar plug removal and cleaning I will leave to the machine shop.

[Walt Fricke]

Tom
If I may ask, why did you knock out the largish steel plug at the far end of the cam carrier? I can't think of any reason to do that unless a) you have two left side carriers, and want to convert one to a right side carrier (or vice versa) or b) you wanted to plate it. But with the engine in place no one can see it, and plating won't extend its life because its life is already basically infinite.

I also wonder what prompted you to pull the valve cover studs. I don't believe these studs are routinely pulled absent thread damage (which is unusual). Lots of work, some modest risk, and just what is the gain?

Are you planning to do this with the case perimeter studs, too? The 8mm studs which connect cam carrier to head?

Some machining operations call for pulling studs - in which case I suppose one could have them plated, though simply purchasing new might be fairly cost effective?

Lots of rebuilders will send out some of the hardware which has to be removed in the ordinary course out to be replated. If for no other reason than much of it is visible and it looks good on reassembly (though Nylocs are often replaced with new), and at least for a shop with a relationship with a replater isn't awfully expensive.

This can be a labor of love, but one might consider if one is making a lot of extra work for little or no ultimate mechanical benefit. Replacing worn moving parts is one thing - replacing functioning static parts is something else.

Or is this a Katrina engine, got soaked in salt water?

[khamul02]

Walt,
All good questions and there is a host of reasons, none are high priority.

First some of these studs were a little damaged. Putting a nut on wasn't effortless which I would think might mess with setting the torque on those studs.

Second, the cam housings had a couple nicks in them where the valve cover gaskets go so I thought I could do a light resurface to those areas as well as replate or replace studs that were damaged.

Once I did a few I thought why not attempt them all and replate or replace studs as needed. I'm looking at belmetric to see if I can find replacement. If I can't then I will just put the dye on them and replate them.

The plugs.. man they are hidden but they really have a coat of rust on them. So I was going to replate them as well but now I will just buy a couple new ones. Anything on this engine that I can get at a decent price new, I'm going to replace.

So, yes I'm going to attempt to pull every stud on this thing. I will leave the heads to the pros. I don't want to mess with those exhaust studs. Are there any others on the engine as prone to break or cause damage?

All that being said.. I have no clue what I'm doing.. I'm enjoying the process and hopefully won't screw anything up beyond repair.

[Walt Fricke]

Well, those cam tower plugs aren't going to rust through, at least from what I have seen, in ordinary use, even after 50 years. A guy could leave them in place, and deal with rust there if so inclined. Save a lot of hassle.

[khamul02]

I wish I would have known that.. I could have put them in the tumbler and coated them with something.

What about all of these studs on the case? Typically, the case gets hot tanked and tumbled which removes the plating on everything. Is it normal then, after a rebuild, that all the studs on a case are not raw with no protection from rust?

[KTL]

I too am guilty of removing the studs on the cam housings. In my experience some of the gasketing surfaces can be boogered up by somebody over the years. Also the gaskets leave some material stuck to the housing. Admittedy that gasket residue is not hard to clean off with a fresh sharp utility knife razor blade dragged across it perpendicularly (is that a word?).

Yes it's a bit of a hassle to take out all the studs. But it's the only way to get the valve cover surfaces nice and clean and flat. I figure if one goes through the trouble to surface the actual valve covers themselves, might as well complement that with the surfacing of the cam housing gasket surfaces? But I certainly admit it's not an absolute must to do this. I'm just OCD about certain things and I hate even weepy valve covers, on top of being somewhat of a clean freak when it comes to engine repair. I'm currently knee deep in the intake manifold R&R on my Corvette and the typical small block Chevy intake valley and the TPI runner connections on the manifold presents so many gasket surfaces (some of which have 30 year old metal reinforced gasket remnants that are unwilling to let go) it's kinda ridiculous.......

I also like to surface the sealing area for the heads and the camshaft thrust plate (the end of the housing) to clean up any crud and make it flat. You'd be surprised how NOT flat the surfaces are. Granted, I suspect the housing has a little bit of "twist" in it upon being removed from the heads and that's why the sealing surface isn't totally true. I color it with a marker and then run it on a piece of quartz countertop that has couple sheets of 400 grit wet sand paper taped to it, to see how flat the sealing surface appears. Honestly I think the most important thing making sure the surface is clean for new 574 orange goop application and that the cam spins freely in the housing when you torque it to the heads. Because it's got so many fastening points, I think it's hard for that surface to NOT mate up well with the heads.

Regarding the steel plugs. The only reason to remove them is if you suspect some crud is trapped around it. Even then, it's not hard to flush around them with some solvent and compressed air. But removing them is not hard at all. A few strikes with a hammer handle or something similar pops them out. Installation is just as easy. Put a swipe of 574 orange goo around the perimeter and uniformly tap it in place around the edges.

Here's some pics of the surfacing on the cam housing. Ignore the 1/8" NPT plug on the end of the housing. After doing that on a few housings, i'm not a big fan of it and would rather just reinstall new aluminum plugs.

[911pcars]

If anything, the exhaust side studs are most susceptible to environmental corrosion. The other fasteners aren't as much; the head to cam housing studs, not at all.

If the exhaust studs are in good shape, leave them, then use anti-seize on them when assembling the engine. Many aren't in good shape. It's easier to R&R them once off the engine. Use steel, zinc or CAD plated if possible.

Sherwood

[Walt Fricke]

Kevin - what are the threaded holes I don't recognize in your cam carrier?

[Walt Fricke]

Kevin - I bet you have a lathe to make new aluminum spray bar plugs? Me, I don't, so the threaded plugs are attractive. Same as for oil passages in the case.

[KTL]

Hey Walt,

Those holes in one of cam carrier pictures are there because it is a 964 turbo part.

No I don't have a lathe for the aluminum spray bar plugs. They're tapered as they come in the bag I believe? I'll check the small number of plugs I have on hand in the nut & bolt organizer drawers and report back in a little while.

[KTL]

Walt,

I checked my aluminum plugs for the cam housing spray bar and they are all a good fit. I checked them by starting them in a couple of housings I have on the shelf. Each one has an end that is slightly beveled to allow smooth fit as it's tapped into the hole.