: studs aren't straight

02-10-10, 08:29 PM
How have people found the easiest way to adjust the studs when the drilling is not exactly correct?

02-11-10, 08:30 AM
There's two ways. Using a nut to protect the end of the stud, hit the stud with quick, firm taps on the end with a rubber mallot. It has to be rubber because it give a soft, dead blow to the stud forcing it to bend a little bit. I've heard of people using a small pipe, and this will work, just be careful not to break the block casting. The first method is the preferred one. If they're severely out of line, take the stud out, bend it in a bench vice and screw it back in. With the rubber mallot you won't have an issue with cracking the block. Until I got the setup I'm using now, I occasionally had to do this.

How's the project going for you guys?

02-12-10, 10:41 PM

I was able to get the studs installed correctly, and wrote up some tips (supplementing your instructions) on how to get the holes drilled correctly.

See My turn to do the at home Northstar headgasket repair - with a twist! - Post #123 (http://www.cadillacforums.com/forums/2140265-post123.html)

02-13-10, 08:47 AM
ejguillot - very nice write-up. I can see the necessity of having an alignment pin in the kit. My CNC guys are running another batch of studs now so I won't bother them with the little details of machining alignment pins - I'll probably run a prototype in my lathe later today and then make a few up out of tool steel.

If the plate is firmly bolted down there shouldn't be one stud out of line- but to be 1/16" off at the tip isn't too big of a deal, easily rectified.

I was on the phone with Norseman in St. Paul a while back and they recommended one of their reamer bits to go from the 1/2" hole that's in the block (roughly) up to 17/32- but they don't have a 17/32 reamer. I'll talk to them and see if they can make a few for trial.

The plates are welded up while the bushings are bolted down to a flat plate, and I allow time between weld passes to avoid warpage. They're solid- and the bushings are machined in a lathe so the threads will not be crooked at all. It's very important to use a tap handle so you can apply even pressure to both handles - keeping the tap from wearing the side of the bushing.

Now for the studs. I've noticed myself the odd one has a bit of resistance. A little bit is OK. But my customers should not have to run a die over them. This bothers me and I have been checking the studs. The last batch was fine but we've had a few with chips in the threads - these got set aside and returned to my CNC guys and they were not shipped in any kits.

I will be checking this next shipment of studs VERY closely. If I see these defects again I will be changing suppliers or buying a CNC screw machine and start running them myself again. I also looked into a thread rolling machine. $41,000 + freight. It's a bit out of my reach right now but if I have to refinance my shop to get it, I'll do what I have to. The CNC company I deal with is very skilled and the staff is exceptionally nice. They have high end machines. I think it may just have been one of their helpers not doing quality inspections like he was supposed to.

To all my fellow Cadillac owners (& repair techs) - I will continue to work on developments for repairing and improving the Northstar, and this includes simplifying / speeding up the stud install. I have plans for a new plate that won't raise the cost of the kit, but will reduce install time to 1/2 or less and improve accuracy.

I assure you all that even if the odd complication arises during the stud install, it is definitely the way to go when doing your head gasket replacement job or rebuild. Nothing will outperform or outlast the studs.

I thank all of my customers, past and future for their support. Part of the profits from the sale of each set of studs / stud kit goes back into Northstar R&D.

02-13-10, 09:25 AM
Jake, feel free to take my writeup and use whatever parts are helpful to make your kit instructions better.

As to my experience: All of the holes I drilled ended up perfectly centered at the block deck surface. It was the deviation from perfectly perpendicular that was hard to control, even with the jig and all.

This is a hole I drilled and tapped that was perfectly centered (note the bottom of the hole):


And this was one of the first I drilled, where the hole was drilled at an angle (see the offset?):


The tap handle I bought for the tap had the 2 handles, so that worked out well.

02-13-10, 10:52 AM
Not bad at all. The drill being so little off over that distance won't matter too much - the final tapping is the most important. A crooked hole can be tapped straight. But the straighter it is, the better. But this is why I say the jig is merely a guide- Hold the drill square to the deck surface and do it carefully- the jig will help make the start straight but it has to be maintained. Once you do a few it becomes second nature.

I have plans for a sliding drill press bolted to an engine stand, an extremely sturdy one. Drilling - 15 minutes tops. A spiral machine tap attatchment to that same low speed, reversible drill press. One pass tapping. 100% accurate and straight.

I want one of these setups in every U.S. state, at least. A shipping company picks up your engine or you deliver to this service provider - probably INNRS shops - within 24 hours you have it back drilled, tapped, and studded for no more than the cost of the stud kit. 100% accurate. There's money in it for shops, and it's a headache and time saver for anyone doing their own HG job. The only thing would be the initial investment in the machine. I will be manufacturing and selling these. I expect shops to be able to have the initial investment back within the first 10-12 engines, each engine taking about an hours time to drill and tap.

I have a lot of ideas and they're going to be implemented soon.

02-14-10, 03:20 AM
This forum is awesome. You technical guys are the bomb - folks like me can only shake their heads in wonder at the craftsmanship and skill it takes to make something like those stud kits and then install them. To a lot of folks this might seem like second nature, but even though I know I could probably pull this off if I had a lot of free time and didn't need my car for a month or so, the fact that you're all so matter-of-fact, businesslike, and collaborative about the whole process is really encouraging and educational. HGs are a lingering gremlin in the back of my mind on every WOT, but being a part of this site has given me confidence to dispell the bad mojo and drive the Starship like it was meant to be driven. I'd like to think that if I had this knowledge, I'd be as ready to share it and put the effort into doing writeups and supplying pics as you folks are. You answer-men (and ladies - I'm sure there are a few at least) are the reason I'm a supporting member today.

That's all from me. Carry on.