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Headstud lenght 7R case 90mm

Hi Pelicans

I have just got my case back from the machine shop for insertion of case savers
even though I instructed him to install them flush to the case , he raised them to the cylinder mounting surface + 5mm? to support the thin part outwards the hole he said .
anyway I really don't want him to redo these as they are installed with red loctite
the headstud length is now 5mm longer (140mm) when using OEM steel .

question is ; can I use OEM or will I not be able to tighten the barrel nut due to the longer studs?

Thought about using Supertec as they come with the different 12 point type nuts



Old 08-03-2016, 01:05 PM
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You could dry fit a cylinder and head and see where you end up. I think there are some measurements you can do, but I don't have the book with me at the office. 5mm seems like a lot - the inserts look more like 2mm proud of the case than 5mm, just based on the 10mm opening for the stud. Depending on the studs you have, that might not be an issue, as they may thread in far enough anyway (i.e. past the top of the insert). The steel studs I have, anyway, certainly would.

I am in the middle of a build, and just put Supertec studs in mine. As you point out, the 12-point nuts completely finesse this problem, and I love it. There are enough things to worry about when building one of these motors (especially for a first timer like me) that eliminating stud height concerns is simply awesome. I rationalize the additional cost the same way I do any of the nice tools I buy - this makes it so much more fun.
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Old 08-03-2016, 02:07 PM
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The studs should go through the timeserts if there installed correctly.
Think your bigger problem may be if the cylinder bases don't clear them.
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Old 08-04-2016, 04:43 AM
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I can't answer specifically. Is the top of the case saver level with the spigot? I wonder if the case saver may lift a small bit as you torque the stud. That may, in turn, interfere with the spigot seal. I think you would want the case saver below the spigot. I may be full of 5hit here...a nice soft copper gasket would probably seal it either way.

Minimum Meat at Spigots with 14x2 case savers
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Old 08-04-2016, 11:23 AM
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Thanks all for your reply .
I think I have to back to the shop and have them installed below the spigot , they are flush now
The Case savers are from Pelican and narrow in the bottom so the stud cannot go through it
Old 08-04-2016, 01:15 PM
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Those kinda look like timeserts. timeserts also have unfinished threads at the inside bottom, and a roller tool is run through to finish the threads/expand and lock in the insert. I would suggest dilivar studs in a mag 7R case instead of steel studs. They last longer than you'll probably own it and way less stress on the inserts. Doesn't look like the cylinder bases have been trued. How about the line bore (hone)? Mag cases usually bind the crank with new bearings if that isn't done.
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Old 08-04-2016, 04:59 PM
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They do look like Timeserts and the threads at the end of the insert are only partly formed to provide the locking action as described above.

The installation tool has a feature which expands these threads and when correctly installed the stud should pass though the insert without problem.

It is unlikely that the insert is long enough to bottom into the blind hole in the engine case as these holes are typically 35mm deep.

If the holes for the Timeserts have been correctly machined using the counterbore tool supplied in the kit then the depth of the flange should be correct and be positioned below the spigot.

If the inserts have been purchased without the full 'kit' it is possible that the thread was prepared using a standard Helicoil STI Tap which is an identical size.

If the counterbore is not be present I would be a little concerned.

It is also possible that the insert needs to be fully installed and you will need access to the installation tool to check this out.

The installation tool has a 'cam' shape to expand the thread correctly and it is better to use this tool as it won't deform any of the fully formed threads in the insert.

If you don't want to use barrel nuts then ARP make an M10 x 1.5 12 point nut which will eliminate the stud height problem.

I would also agree with using Dilavar in a mag case.
Old 08-05-2016, 12:29 AM
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I thought the common wisdom now was to never use the dilivar studs when the engine is rebuilt because of dilivar studs breaking. Is this not true for a 1974 7R case?
Old 08-05-2016, 09:00 AM
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I believe that the current 'coated' Dilavar studs are much better than the original parts that used to be used on the SC engines.

The coating reduces the problem caused by the salt spread during hard winters and the susceptibility of Dilavar to intergranular corrosion caused by chlorides.

I would be careful about the source of Dilavar studs and would only tend to buy genuine Porsche parts as it also seems likely some aftermarket 'dilavar' studs were very poorly made.

Old mag cases have probably suffered from stress relaxation by now, particularly if they have been used with Thermal Reactors, and I think they need every chance they can get if used with a Nikasil barrel.

The won't be as bad is used with a Biral.

There are some issues with some aftermarket studs and this is concerned with the shank diameter.

If this diameter is increased compared to the standard stud then the pull out force due to expansion will increase and this could become an issue.

We make a Titanium stud which has a lower modulus of elasticity and helps to control the force increase due to expansion but they are still not as effective as Dilavar.

Last edited by chris_seven; 08-05-2016 at 09:29 AM..
Old 08-05-2016, 09:27 AM
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The inserts are Case savers bought from our host see pic.

John Walker ,
I just tried to make a trial assembly of the cases with crank only and new bearings .
and even though it all have been checked by machinist for straightness and I have checked with Plasti gauge the crank DOES bind when I tighten the last 10mm nut inside the chainramp really frustrating

Guess I have to ship it to Ollies for line bore as I should have done to start with.
nearly same price as shipping it to Germany .


Old 08-09-2016, 06:09 AM
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