10mm head studs versus 8mm

[bugnut68]

For a street/bracket racing engine with 8.6:1 compression (not sure what other details may be vital), what disadvantages would there be to running 10mm head studs versus 8mm head studs?  I'd always heard that 8mm head studs held torque better.  I'm basically up against having to get another case machined for my 2017 build, and all I have is a Type 3 'U' code dual relief case featuring 10mm head studs... just wondering if there are any disadvantages to using these studs versus having 8mm case savers installed.

[nicolas]

i don't really see a problem with 10mm studs (apart from a different torque figure, but to do the same thing) since you use 90.5's
check also that you maybe drill the oilpressure hole beforehand as type3 cases don't have that drilled.

[bugnut68]

i don't really see a problem with 10mm studs (apart from a different torque figure, but to do the same thing) since you use 90.5's
check also that you maybe drill the oilpressure hole beforehand as type3 cases don't have that drilled.

I forgot about that part...you're right, this case isn't drilled for the pressure sending unit.. I read elsewhere that 10mm studs tend to pull out of the case, but I think that's only for cases that haven't been set up with case savers.

[Airspeed]

So, your T3 case has inserts for 10mm head studs?

[bugnut68]

So, your T3 case has inserts for 10mm head studs?

I'll have to go back and look... seems like as memory serves that was the case.

[Sander/DVK]

As I remember good they have 10mm inserts, but the stud it self is 8mm.

[bugnut68]

If that's the case, this case doesn't have case savers... definitely the bigger studs I have, that much I do know.  I'm right now trying to decide whether I want to move ahead and find another case ($$$) or scrap the project for now.  I definitely know I don't want to put any more work/money into the existing case given it wasn't ideal to start with.

[Diederick/DVK]

I definitely know I don't want to put any more work/money into the existing case given it wasn't ideal to start with.

very much understable, but when you've got this far why not swap cases? if that spare case you have suffices, why look further?

[bugnut68]

I definitely know I don't want to put any more work/money into the existing case given it wasn't ideal to start with.

very much understable, but when you've got this far why not swap cases? if that spare case you have suffices, why look further?

Well, I'm not so sure it's an ideal base, since it would need to have case savers for 8mm studs installed, plus drilling and tapping for a Type 1 style pressure sending unit, and any other hidden issues that may or may not exist.  Ideally, I would hunt down a case already bored for 90.5 and machined for full flow at minimum with 8mm head stud case savers... just want to try and minimize the amount of machine work needed, if possible, rather than start at ground zero.  If money was no object I would buy a brand new case with all the work done, but at $800, I'm floored how much prices have soared in recent years!

[nicolas]

if the type3 case is allready machined for 90.5's use it. or if the case is very good at the bearingsadles and cam sadles use it. the hole is easily drilled and tapped by hand. just make sure that indeed you have a good core to start with. maching isn't cheap, so you better use what will last you a few engines or regrinds imo.
i don't see too many issues with 10mm studs you can use the original ones and with the 8.6 CR it will work. better as using cheap/crap 8mm studs even if they have inserts. but make sure the treads of the 10mm studs in the case are in good condition

[Diederick/DVK]

what's the fuss about 10mm studs anyway? did I miss something?

[Fastbrit]

10mm studs are great! I always used to use cases machined by Rimco WITH case-savers (for 10mm studs), machined for 94mm cylinders and used on my turbo motor with up to 28psi (2bar) boost. Never pulled a stud. Used 10mm studs that were slimmed down over part of their length for use with the 94s, but the great benefit was the increased thread area compared to the regular 8mm studs. Yes, boring the case for 94s did just touch the 10mm case savers, but that was never a problem. This was the standard set-up for Dave Kawell for years, for any Type 1 turbo application, street or strip.

The early stock cases that had 10mm studs screwed directly into the case could be weak but I still bet there were many cars running these cases back in the day without problem. Personally, if the case you have is good in all other areas, I'd maybe plan on having cases savers installed if you want, but on the whole I agree with Nicholas...

[Rick Sadler]

As a side note. There are case savers (stud inserts) that have a 12mm x 1.5mm thread which is the same thread as the factory 8mm case savers. Most of the pre 1990's 10mm case savers that were used by machine shops were either 1/2"-20 or 14mm-1.50mm od.

[TexasTom]

Here you go:

http://cgi.ebay.com/ebaymotors/TIME-SERT-NEW-Porsche-VW-1085-M10X1-5-Case-Studs-Kit-/280429911160?pt=Motors_Automotive_Tools&hash=item414aecdc78

extra inserts:

http://cgi.ebay.com/ebaymotors/Insert-VW-M10x1-5-10-Inserts-Part-10155-/280429911597?pt=Motors_Automotive_Tools&hash=item414aecde2d

[bugnut68]

Sadly, this case I have is still a 1600... hasn't been bored out yet, otherwise I'd likely be all set to go ahead with it (pending a check on the main bearing saddles and thrust area, of course, as I have no idea what size bearings are in there as of the moment).  I'm currently in the "take a break for an indeterminate amount of time" phase, so I'm in no rash hurry to come up with a solution right away. 

[Airspeed]

..... but make sure the treads of the 10mm studs in the case are in good condition

Thats the kicker! A lot of the old original cases with 10mm studs have just exactly that problem.
You'd never know either till you see traces of oil between the cylinders and heads...(or worse, when you start hearing pounding)
I would never use an old case with the original 10mm head studs which are screwed directly into 40 years old magnesium-alu with over 100k miles and use 'as is' for a performance engine.
The studs aren't the problem, its the way they were attached into the cases back then, that is.
10mm studs in themselves are of course better then 8mm for holding big cylinder pressure, no argument there 

[Diederick/DVK]

never head of this problem. wouldn't applying loctite help overcome the issue?
basically what you say is that a case with 10mm studs needs case savers?

[Corally]

never head of this problem. wouldn't applying loctite help overcome the issue?
basically what you say is that a case with 10mm studs needs case savers?

Locktite only helps preventing it from "unscrewing" itself. But that's not the case. Casesavers or helicoils or what ever will allways be better because they can move and thus spreading the load more evenly within the case material.

[bugnut68]

I looked at the engine in question yesterday and it's definitely 10mm head studs with case savers... so I could either run it as is with the 10mm studs or else have case savers for 8mm head studs installed.  Next step is to tear it apart (possibly this week) to see how it looks inside and determine if it's been align bored at all (no stamped numbers externally).  By the number its' a late '60s Type 3 case (dual relief).

If this case doesn't prove suitable, I'm pretty much done (by my own decision) as I'm simply not willing to spend nearly $1,000 for a brand new machined case.  I can likely manage to have a case machined but I'm just not able to put out the money for a brand new  mag or aluminum case.

[Catbox]

The case that I will be using for my upcoming 2332 has the 10mm studs with the case savers installed.
The only issue that I had was that two of them were missing and they are the fine thread type. 
The local shop didn't have any but the resident machinest said he might.  He said that he had to really dig around to find just the two that I needed.

My case is machined for 94's and none of the case savers are showing through where it was opened up.
It was previously a 2332 turbo sand car engine, so I doubt it was babied at all.

You will be fine, build it and smile.

 

[bugnut68]

Meh, it's no big deal either way... I'll tear this 1600 down tonight or Friday and see how it looks inside.  I'm giving myself 90 days to decide what I want to do.  The positive is it's not the end of the world if I move on for a while and do something else to entertain myself, I can always come back to this stuff down the road.  It's just not a good idea, IMO, to force myself to continue if I'm not 100 percent committed.

[bugnut68]

And the hits just keep on coming...lol.  Tore the 1600 down last night after work only to find that not only was it hacked together by some moron (massive gobs of orange RTV sealing the oil pump in the case and all the pistons were installed with the arrows facing the pulley end of the engine, for starters), but the case was align bored out to .060".  Saw the main bearings still had sizes inked on the outer shells (EXT. 1.5mm, INT STD). 
I verified the saddles with my handy CSP case measurement tool, and confirmed .060".
What are the odds of ending up with another case with the exact specs as what I just built the 2017 on?  Simply astounding in my shop apparently.
I've got a few calls to make.  Hopefully I can land a good deal on a good, used case already machined and what not, because I simply cannot justify at this time $700 or better for a brand new case (preferably mag, as I know the aluminum cases have things you really have to watch for).

[Speed-Randy]

Ryan, I have a few cases laying around the garage, I would be happy to give you one of these and will even drop it off at Rimco for any machine work you want done to it. You will have to pay for any work and shipping, but I will donate the case if you're interested. Stock VW 1600 base case, let me know

[bugnut68]

Thanks for the offer, Randy.  That's very generous of you, and I'll keep you posted.  I'm waiting to hear from a couple contacts up here in Oregon and will let you know one way or the other once I hear back from them.

On a sidenote, I'll try to post some pics of this engine I just tore down.  I found it interesting that it had no stampings anywhere of having been line bored and it couldn't have put together terribly long ago.. .cylinder walls still had hone marks present and the bearings looked relatively fresh (except the cam bearings, one was pretty scored up--engine came out of a baja).  The crank featured standard journals but the dowel pin holes were wobbled from a loose flywheel.  Orange RTV used as oil pump sealant...lol.  I'm surprised there weren't more issues inside.

[bugnut68]

well, if there's any kind of saving grace, it's the fact that I can transfer the main bearings from my 2017 over to this 1600 case I just tore down.  The 1600 needs a crank and I have like four extras sitting around, with .010" main journals.  Everything else inside the 1600 looked good, as I think it wasn't too long ago it was built, from what I can see.  So I can likely put it back together minimal purchases (rod bearings, gaskets and maybe some minor hardware) and either slap it in the car as a backup or else sell it down the road as a turnkey unit.  A 1600 is a helluva lot easier to assemble and should be fairly easy get back in running order in a timely fashion.