Mike Simard

Here are some serious fasteners for your engine. These are custom made 4340studs. They are heat treated to proper specs and the threads have been rolled in the hard condition. They have been destructive-tested for yield to develop optimal tightenting procedure. This set is made with an effort usually only seen in big-budget racing. They have approximatley twice the clamping force of stock studs but more important is how they handle loading compared to a common stick with threads on the ends. These have 1.5 pitch threads to take advantage of every thread in the block and fine 1.25 threads for torquing. Included are exact angle tightening instructions.

I consider main and head studs to be very important to strength of an engine and I feel that the reasons they are important are not understood by many engine builders, here's why:

It can be assumed that a high performance engine will see some strong detonation type events sooner or later. Even if the tune is perfected on the dyno, in the real world all it takes is a fuel pickup being uncovered during a turn, a weak injector or an intake leak, Those are a few of many ways an engine can go lean and detonation occurs. Even if the mixtures stays constant, when a valve seal stem starts letting oil by or a cylinder wall flexes from stress and lets oil by, that's yet another way detonation can occur when not expected. Detonation or harmful combustion events should be assumed as likely and planned for.
The first idea idea to improve strength is usually to slap some ARP studs in or even drill and tap for a larger size. The problem is when the stud is made from a bar with no undercutting to allow stretch. Any fastener stretches during tightening, that's why they work and don't come loose. A solid body stud will stretch mostly in what threads are not screwed into the block. That limited amount of material must handle the force of tightening, thermal expansion and detonation without yielding. If it yields you then have a fastener with low tension. An under tensioned fastener is actually less strong and will hammer the block. If you've ever had to retorque an engine and it did require movement your fasteners may have yielded and who knows how they did/will transmit forces after that.
I strongly believe that many cases of broken blocks and walking main bearing caps seen in high performance circles are caused by fasteners that didn't handle forces well because of the hot rod shop design of the universally admired aftermarket fasteners. Here's my solution and I used the full resources of an aerospace shop to fullfil it.

$650 per set. Included are nuts and some grade 12.9 cap screws for the outter 8mm holes.
For $850 total I'll include a girdle. It adds some rigidity and is a convenient place to attatch windage stuff. The studs can be used with or without it.

Studs are ready to ship now, girdles are being made now and will be ready by 11/12. The girdles are slightly different than the one pictured, I've opened up the hole for the 10mm ones and added meat around it.

SwayBar

Schwing! That's beautiful.

atb

Did you have to align hone after putting the extra shuttle pins in?

Too cool Mike, thinking it over.

Fabio421

Do you have a picture of the stock girdle to compare?

Thanks

atb

My machinest wouldn't shufffle pin a block I had because he wasn't confident that the girdle would re-align correctly. I guess if you shuffle pinned first, and then align hoaned the main line you'd be good to go. Didn't think about it at the time.

atb

Fabio,
Mike's girdle stacks under the stocker, not in place of it. It's just for extra ridigity, it doesn't carry any bearings.

Mrmerlin

Mike, thats some very nice hardware, and a girdle support you are setting the notch quite a bit higher, goodluck with selling these fine additions, Stan

BC

You know I am in Mike - I emailed you.

Jim Morton

PM sent.

Thanks.

90 S-4

Mike,
I'm in for the Webbed Girdle & Studs package.

IcemanG17

Mike
Great looking work....hows the engine coming?

Mike Simard

Thanks for the kind words! It means alot to hear because I spent a silly amount of time working on these and expected the sound of crickets and tumbleweeds blowing by if I ever mentioned them

Fabio, the girdle is a flat plate that sits on top the the lower block section, the oil pan now mates with the girdle. Conveniently the surfaces of the lower block half are at the same level so this is a way to tie the center area around the large studs to to pan rail. It's not obvious that something like that can add strength, domestic V8s with their little individual main bearing caps offer a glimpse into what kind of forces are seen. They do things like break in between the big and small stud of a '4 bolt main'. Also common is for a main cap to squeeze inward so that 'shuffle pinning' a cap, even though it's located within walls, can help by keeping it from moving inward. A 928 is really a work of art in that its lower block half is one piece but it still sees the same forces. I noticed in Project928 that the early 928 engine had the smaller stud rows added early on. There was mention of breakage in the lower block half. Just a guess but I suspect that it's likely for the lower block half to have split in between the big studs and the pan rail. A girdle can help in that way. In a domestic V8, even a strip in between the 2 bolts of an individual main cap can help. The pic below shows the lower case half without the girdle, you can see the machined surfaces common to the center and outter rail.

Adam, I did have it align honed after adding the dowels. I can understand why your machinist would be concerned. Here's a pic of what I did. Those rounds within the mains are machined the exact size of the bearing shell. The block was then clamped together and dowels reamed. After that it was surprising how well matched the halves were. I'd also machined the lower block surface, by the time they went on the align hone machine it went very well. If the original bores weren't so egg shaped I probably could have gotten away with not honing. If you want to do the same I'd be glad to loan you the round nubs.

IcemanG', I had forgotten all about my engine lately. It's been sitting at the shop where it needed to have the Nikasiled cylinders honed, that seems to be a long process requiring months of patience The engine hasn't been missed because the rest of the car has to be built from a bare tub. Building a cage from scratch is a mind boggling amount of work and now the simple sounding idea of replacing suspension bushings with a spherical bearing has been a project to see many moons. Still, there is something very rewarding about working on a 928 project, it's more worthy and brings more pride than any other automotive project I've done.

slate blue

Mike I have to say that is mighty impressive, your dedication and expertise are of great value to us as a community as a whole. My money has run out for a while as I'm getting married. Just bought a thing called a diamond. They are useless as far as I can tell

I take it you are also using some rather good studs to hold the heads down? I need to buy a set of those for my new engine. I take it you would recommend the fine pointed nuts for use on all studs?

Thanks and well done

Greg

atb

Mike, what are the holes in the girdle above the outboard main studs for?

BC

Now how about a drop in Deck plate?