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9/16 Head Studs

3K views 7 replies 2 participants last post by  eschaider 
#1 · (Edited)
#2 ·
The 9/16 and ⅝ inch head studs are primarily a fixture from the blown alcohol and nitro classes, Robert. Our OEM head stud diameter of 11mm is essentially 7/16 in SAE speak. While there is likely adequate material in the casting to go to a ½ inch head stud, going larger gets progressively more risky on two different fronts.

The first front is the amount of material around the stud anchor point. Each time we go up in stud diameter we reduce the total amount of material anchoring the stud. One step up from 7/16 to ½ probably doesn't matter. Above that the ice starts getting thin and so does the block material. The second front is the inherent strength of the casting. ARP2000 1mm studs begin to crack the block at 115 ft/lbs of torque. The stud seems to be OK but the block is not. Bigger studs load the casting more heavily which brings us back to the first front issue.

In the FWIW column, Accufab offers a step stud that has a 9/16 coarse thread on the block side and a ½ fine thread on the nut end of the stud. Predicatably you will have to do a little machining to se the studs but there is a ready made package if you wish to experiment.

The other path that might be worth exploring is to ask ARP to make some 11mm studs out of their 625 steel which is an even larger improvement over 2000 steel than 2000 steel is over 8740 steel.


Ed
 
#3 · (Edited)
Ed, thank you for the insight! I'm sure I would never get near the need for studs of this magnitude, but it is always fun to hope, and learn something in the process! Thanks!

Actually Ed, as I already have your attention, what are your thoughts on oil squirters in a modular engine like ours? I have been doing research, and all I have found is people going back and forth about how you either must have them, or having them will destroy your hard-worked-for investment in a variety of engine platforms. As all 4.6s never came with squirters from the factory, it would obviously be a retrofit. But, besides that hurdle, what are your thoughts? My current mentality is along the lines of "what could a little extra piston and pin cooling and lubrication hurt?"; but maybe I am missing something a more seasoned individual like yourself is aware of.

Robert
 
#4 ·
Oil squirters are used to cool the underside of the piston crown. Because the application is a splash style of cooling they will also contribute to wrist pin lubrication.

The only reason not to use oil squirters is if your block is not machined for them or your oil pump is not properly sized to support them. If the block is not machined for them then you have a problem installing them. If your oil pump is too small to support the squirters and properly lubricate your engine you will kill one or more bearings somewhere in the engine.


Ed
 
#5 ·
Thanks! Was seeing a lot of what seemed like people spouting garbage about "too much oil on the underside of the piston will cause sudden thermal shock and break pistons". Planning on dry sump, so lubrication would not be an issue. Might see if I can undertake a retrofit of sorts on oil squirters. I'll have a spare iron block 2v lying around somewhere I might mess around with. I could use a new territory project.
 
#6 ·
If you are installing them on an iron block you may not have enough material around the oil galley to fit the squirters properly. If you use an aluminum block you have a better chance of having enough material to work with. Look at the Coyote squirter placement for your model. It will allow you to use the ready made Coyote squirters and also show you where to put them to avoid the rotating assembly.

With respect to the internet banter about thermally shocking the pistons into a death spiral, I do not know of any such occurrences. I would not give a second thought to breaking the pistons from using oil squirters. On the other hand, there is the possibility of opening up a quantum mechanical black hole (first suggested by Dr. Stephen Hawking in 1971) on the underside of the piston crown.

Normally a quantum mechanical black hole would simply just evaporate, either totally or possibly leaving only a very weakly interactive residue. Of course there are the worry warts that forecast horrific end of the world scenarios if a micro black hole does not evaporate and begins to grow. Naturally, as the driver of the vehicle you would be the first causality as the now growing black hole began to feast on the matter in the nearby fabric of space-time.

On balance this could be even worse than the thermal shock scenario that the underside of the piston sees. The good news however is that there has never been any known quantum mechanical black holes discovered that have not evaporated. Sooo, at the end of the day you should be fairly safe and so should your pistons.


Ed
 
#7 ·
If you are installing them on an iron block you may not have enough material around the oil galley to fit the squirters properly. If you use an aluminum block you have a better chance of having enough material to work with. Look at the Coyote squirter placement for your model. It will allow you to use the ready made Coyote squirters and also show you where to put them to avoid the rotating assembly.

With respect to the internet banter about thermally shocking the pistons into a death spiral, I do not know of any such occurrences. I would not give a second thought to breaking the pistons from using oil squirters. On the other hand, there is the possibility of opening up a quantum mechanical black hole (first suggested by Dr. Stephen Hawking in 1971) on the underside of the piston crown.

Normally a quantum mechanical black hole would simply just evaporate, either totally or possibly leaving only a very weakly interactive residue. Of course there are the worry warts that forecast horrific end of the world scenarios if a micro black hole does not evaporate and begins to grow. Naturally, as the driver of the vehicle you would be the first causality as the now growing black hole began to feast on the matter in the nearby fabric of space-time.

On balance this could be even worse than the thermal shock scenario that the underside of the piston sees. The good news however is that there has never been any known quantum mechanical black holes discovered that have not evaporated. Sooo, at the end of the day you should be fairly safe and so should your pistons.

Ed
Ed, I got a hearty chuckle out of this! But darn you if it didn't hurt! I have a cracked rib so your great scientific insight might have given me a new bruise! But no matter. Thank you for your thoughts, once I move into my new apartment with my new garage (so excited to finally have a workshop!) I will start looking at what I can do. I have an 05 aluminum block I am using for my build so hopefully I can make something work. I will consult here before any final machining. It would be great if this is not a huge undertaking or impossible, because it could become another step for better longevity in these already robust motors.

Thanks!
 
#8 · (Edited)
All kidding aside Robert, be sure to do a careful inspection of the block by the main ol galley. The Coyote blocks have a boss cast into the oil galley just for machining the pad and anchor bolt boss for the squirters. This is what the Coyote squirter pad location looks like;

Automotive tire Motor vehicle Automotive design Alloy wheel Rim


The lack of that pad may cause permanent damage to a Modmotor block if you attempt to fit squirters too. I would get a scrap block from a salvage yard and do some forensic work sawing it up and checking for how much aluminum is actually there before attempting to machine a mounting pad onto an otherwise perfectly good block.

As you already know, there are any number of sources for squirter block offs for Coyotes - and the engines perform very well w/o the squirters. If you were involved in some sort of endurance competition then I could see possible advantage for the use of the squirters. Absent that sort of usage you might cvery well be chasing a distinction without a difference.

Ed
 
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