Thread: Installing steel rocker arm studs in aluminum heads

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Hi,
On the installation of steel rocker arm studs and steel guide plates into an new aluminum head, what should I use on the threads? Anti-seize? Permantex water sealant? How about the guide plates, where they meet the aluminum heads? Moly lube? Anti-seize?
The aluminum/steel interface must need something and don't some of the studs go into the water jacket?.
Sent question to head manufacturer but no response, need some real world advice from real engine buidlers. Give me a hand.

I've become a fan of the ARP fastener lube.

Even where the fastener enters the coolant jacket, it seems to provide the correct torque and sealing.

IMO the concern is galvanic action causing the steel & aluminum to basically corrode and stick together. This is a problem for threaded objects that you will be removing later, but I cannot see that it's a problem for steel studs that you are installing once and never taking out again, other than to change out guide plates. Just know that in the event you DO have to remove them in the future you may be heli-coiling some (or all) of them to put in new.

The rocker studs hold the guide plates down------always use some kind of lube/sealer if water jacket involved but most studs go into a boss cast on the head-some intake rocker studs will penetrate into intake port and can cause vacume leak. there are some longer studs to allow more thread surface(well actually, I think it started by placing the exhaust rocker higher up for correct geometry and they broke the bosses off so somebody did some longer studs-always use 7/16 thread, never use the 3/8 into alum. save the helicoil for repair option later. seal the threads into the intake ports or you will get a leaky, smoky,vacume leak.

Proper alignment of the process is vital

Originally Posted by jerry clayton

Proper alignment of the process is vital.

And so is the proper pushrod length.....
https://www.youtube.com/watch?v=o5is9BsH5OU

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Originally Posted by DennyW

I'm sorry guys, but when I work with aluminum, and some things like areas that usually go bad normally, I always prepare it for the worse situation. Anything aluminum, it gets helicoils. It's a pay me now, or pay me later kind of thing. There are several different helicoils, for any type, or any part of an application. At different strengths. Hell, the Military uses them all the time. If you want a thread to stay where it is supposed to be, a helicoil will keep it there far longer. If the aluminum has a rolled thread, you have a better chance of keeping the thread, but, corrosion will catch up to you. And if changing the thread size from 3/8" to 7/16", why not just go ahead and get all the help you can right then ? And always use sealers, and anti-seize where they are needed. Any way, that is my thinking, and has never let me down.

While I understand your position completely, I would have a hard time drilling out the threads on a brand new head and installing helicoils. In the event that you have any problem with the head you've given the manufacturer an out by modifying it before it's even proven. Using your logic would entail drilling out and helicoiling the spark plug holes, too, as they are just a failure waiting to happen, but look at the number of heads out there that are doing just fine provided anti-seize is used on the plugs. In a racing application I could see going the helicoil route more than for the street, but for a street application I'm with Jerry - save the helicoils for repairs later, especially on a rocker stud that will very likely never be removed once it's installed. Just my $0.02.

Edelbrock aluminum heads have inserts at the rocker and exhaust bolts factory installed, and other may as well. If in doubt check with the manufacture and see what they have and/or recommend.

If the threaded area of the spark plug extends into the firing chamber the build up on the treads can strip the aluminum on the way out, wether anti-seize was used or not. This same condition can make it very difficult to remove plugs in an iron head too. It is important to use the correct plug that matches the head design, often we hot rodders forget this.
Sorry off topic...

Just a thought on the issue of corrosion between the guide plates and the aluminum head bosses; I don't know whether it would hold with this application, though; on electrical connections, especially where dissimilar metals are involved, I have always used some sort of anti-corrosion grease when making the connections up. In high voltage work, we cleaned and greased all connections, and then tested them for resistance before energizing them; bolted connections were especially critical, clamped ones not so much. Now, I can't say that anti-corrosion grease, brands I can think of right off the top of my head are "Anti-Cor", and "No-Corrode", would be useful or effective in an engine where aluminum and steel or cast iron are in contact under pressure of a bolted joint, but it is something to consider; perhaps a heretofore un-considered alternative to anti-seize.

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Most anti-seize compounds are conductive (some more than others) and are designed for use on threaded appliances that need to complete a circuit (leak energy), spark plugs exc.. Most anti-corrosive compounds are NON conductive and designed to prevent corrosion and not leak electrical energy. The use of anti-corrosion compound on house current (120/220 volt, also used in high voltages) is to coat and prevent the metals from any corrosions that could be present and would harm (insulate) the mechanical make up of the connection, without allowing the energy transmitted through them to leak out via the compound itself conducting it.

Most automotive applications use anti-seize compounds (bolts, spark plugs exc..), as it is important for all components to conduct a good ground without interferences from corrosions. With the exception of anti-corrosion compounds being used on top of battery connections to prevent corrosion from forming without any leakage to surrounding surfaces.

Because of the coolants (usually mixed with water) and the 12 volt DC electrical systems that flows through our motors, electrically induced corrosions are always present, which can cause and speed up electrolysis. Anti-seizing compounds are used on all of our motor's grounding type and dissimilar metal connections to lesson this condition by allowing a lubricating protection that seals the connection while promoting its conductivity, thus lowering the chances of electrolysis forming between the mating surfaces.

The exception being where an appliance or bolt enters into the water and/or oiling systems and requires a better seal from their internal pressures.