1964 326 hollow oil rocker arm studs replacements or fixes
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post #1 of 8 (permalink) Old 03-03-2018, 01:17 PM Thread Starter
 
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1964 326 hollow oil rocker arm studs replacements or fixes


Hello from Des Moines, Iowa. First post on the forum! I have a 64 326 that a buddy and I pulled and is currently getting cleaned up at a local machine shop. There are 3 or 4 of the hollow oiling rocker studs that are plugged and the shop would like to have some back-ups in case they break when then try and pull them, so I am on the hunt for replacements.

I've already spent quite a bit of time doing research on the forum looking for solutions to this issue if I can't find replacement studs and I have seen multiple post where folks have replaced these with solid studs and have changed over to hollow push-rods etc, but I would like clarification on what exactly needs to be done for this to be 100% correct.

-Do the oil galley's that feed the heads need to be blocked off? What does that entail?

-I've also seen where someone mentioned having to reverse the cam bearings to close off the oil feed to the heads, is that something that should be done as well?

-What would be the best replacement studs to use AND how does that change affect how you adjust rockers/valve lash etc.

I'm sure that I am probably missing parts of the puzzle, but this should be enough to get the ball rolling. This would be a great thread to have for others that are in the exact same position that I am in. I'd really prefer to keep it stock and not alter the heads at all if possible, but if it's a lost cause, I would really appreciate some advice on the correct way to remedy this as this is the only thing that's holding up the process of getting this old girl back together.

Looking forward to sharing photos of the rebuild! Here's a couple from when we pulled it:
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post #2 of 8 (permalink) Old 03-03-2018, 04:43 PM
 
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Here is what I found on plugging the oil supply to the rocker arm studs," With the changes in rocker arm oiling came new head gaskets. Those for 1964 and earlier had a hole for the passage that supplied oil to the galley in the heads to feed the studs. Later gaskets didn’t have that hole. When installing 1965 and later heads on an earlier block one common practice was to use a later head gasket without the oil hole. However, many gasket companies have consolidated part numbers, the result being some applications have been expanded so to broaden the application later head gaskets may have the extra hole. In that case another option is to plug the supply hole in the block by drilling and tapping it for a 1/8-inch pipe plug."

On the rocker arm studs, "Another unique feature is the valvetrain. Prior to 1965, Pontiac’s stamped steel rocker arms were lubricated by oil delivered through the heads that lead to passages in the rocker studs—holes in the sides of the studs delivered lubricant to the rocker balls. We opted to install screw-in studs from COMP Cams. Another reason for changing the studs was adjustability. In stock form the rocker arm nuts bottom out on the shouldered stud and are torqued to remain tight—any change in deck height, head thickness, or valve stem height alters rocker arm geometry and there is no way to correct it. The cure is screw in studs with locknuts, and in some cases custom-length pushrods are also required."

My guess would also be that if you installed screw-in rocker studs, they are solid and will not allow oil through, thus shutting off the oil supply to the heads the same as installing the 1/8" pipe plug. You also want to change your rocker arms if they do not have the oiling holes in them for pushrod oiling.

ARP number-290-7201 rocker stud kit is specifically designed for converting an original pressed-stud cylinder head to threaded studs. The ARP studs feature a typical 7/16-inch upper with a 1/2-20 base. The base threads are purposely left slightly long and must sometimes be trimmed to fit. Overall stud height: 2.000 in. * Screw in thread depth: .1.025 in. * Adjuster thread depth: 1.05 in. * Shank diameter: 7/16 in. * Base diameter: 1/2 in. coarse * With roller rockers, and girdles * Not to be used with OEM style self locking nuts. NOTE- I believe you may have to spot face the stud pedestals flat.

However, these are offered on Ebay and state they can be used without any mods to the pedestal. Might be the way to go: https://www.ebay.com/itm/Pontiac-GTO...-/350433783872
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post #3 of 8 (permalink) Old 03-03-2018, 05:26 PM Thread Starter
 
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Thanks for the info and links PontiacJim! I'll spend some time this evening looking this stuff up. Seems like going this route makes the most sense.
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post #4 of 8 (permalink) Old 03-07-2018, 07:57 PM Thread Starter
 
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Updates on the 64 326 heads. The machine shop managed to get the rocker arm studs unplugged and cleaned out! With that in mind, comes another question. Should I use solid pushrods/rockers?

I am thinking about potentially putting hollow push rods in for additional lubrication (maybe even rockers with oil holes) OR just split the different and only use hollow push rods along with the original stud oiling.

I realize that the heads weren't originally designed for hollow push rods or rockers with oil holes. What's everyone thoughts? Could adding these options potentially cause issues?
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post #5 of 8 (permalink) Old 03-07-2018, 09:02 PM
 
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Originally Posted by Pontiac-K View Post
Updates on the 64 326 heads. The machine shop managed to get the rocker arm studs unplugged and cleaned out! With that in mind, comes another question. Should I use solid pushrods/rockers?

I am thinking about potentially putting hollow push rods in for additional lubrication (maybe even rockers with oil holes) OR just split the different and only use hollow push rods along with the original stud oiling.

I realize that the heads weren't originally designed for hollow push rods or rockers with oil holes. What's everyone thoughts? Could adding these options potentially cause issues?
I have never rebuilt an older Pontiac engine, so I assume the pushrods are indeed solid versus hollow due to the fact that they oil through the rocker arm studs. Am I correct?

However, I would also assume that you don't want oil pressure bleeding out all over the place and lose oil pressure to your mains if you used both. Use either one set-up or the other, hollow pushrods for oiling through the rocker arms or go factory with the solid pushrods(?) for oiling through the studs.

I don't think it should matter if the rocker arms have oiling holes if you use solid pushrods like factory. You will need the oiling holes of course if you go oiling through the pushrods and block off the oil passage to the rocker arm studs.
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post #6 of 8 (permalink) Old 03-07-2018, 09:20 PM Thread Starter
 
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I have never rebuilt an older Pontiac engine, so I assume the pushrods are indeed solid versus hollow due to the fact that they oil through the rocker arm studs. Am I correct?

However, I would also assume that you don't want oil pressure bleeding out all over the place and lose oil pressure to your mains if you used both. Use either one set-up or the other, hollow pushrods for oiling through the rocker arms or go factory with the solid pushrods(?) for oiling through the studs.

I don't think it should matter if the rocker arms have oiling holes if you use solid pushrods like factory. You will need the oiling holes of course if you go oiling through the pushrods and block off the oil passage to the rocker arm studs.
We're on the same page. That's where I was going with this. The heads were originally designed to give the correct oil pressure with just the rocker arm stud oiling. Adding something like hollow pushrods would allow more oil to circulate/lubricate the heads, but I had a feeling that doing so would compromise the oil pressure and starve other parts of the motor. Thanks again PontiacJim for sharing your thoughts on this.
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post #7 of 8 (permalink) Old 03-08-2018, 09:43 PM
 
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You can make the little 326 a nice peppy engine. They offered a 326HO which was to rival the HP small blocks of that class. A few "modern" upgrades for a little more HP and I think you will like the engine.
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post #8 of 8 (permalink) Old 03-09-2018, 12:06 AM Thread Starter
 
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You can make the little 326 a nice peppy engine. They offered a 326HO which was to rival the HP small blocks of that class. A few "modern" upgrades for a little more HP and I think you will like the engine.
I've looked up information on the 326HO. From what I've read, they added a different intake to accommodate a 4 barrel carb, dual exhaust, as well as increased the compression ratio some.

My car has dual exhaust installed and I have already ear-marked an edelbrock intake,4-barrel carb, and a slightly more aggressive cam....so she'll be closer to an HO spec.

Do you know specifically what Pontiac did to increase the compression ratio? I know you can throw on a thinner head gasket on and/or deck the block. I would think from a Pontiac assembly line perspective, it would've been something easy to install/swap in the block like different pistons. If they did use different pistons, are you aware of what a modern equivalent would be? I'm just spit-balling at this point..curious to hear your thoughts

Last edited by Pontiac-K; 03-09-2018 at 09:44 AM.
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