Exhaust Stud Replacement

[Steam Driver]

I have a problem; what's the best way to solve it? Here's the situation (this gets rather lengthy; please bear with me):

The P/O of this engine mixed and matched SC parts for a performance enhancement (real or imagined) that was popular in the eighties. He backdated my 1982 to pre '81 specs; big port heads, big port CIS, distributor w/no vacuum advance, advanced cams AND a pre-'73 set of heat exchangers with the thin fl. The problem is I live in a "special" area in TN with draconian emission regulations and I need to return to the catalyst exhaust system.

The problem is that the heads on my engine have studs for the thin flange HE's, thus being too short to mount the thick flange HE's. I am under the impression that all of the cat system HE's are thick flange - is that so?

I was going to try the same successful regimen I used to remove my cylinder head studs on the exhaust studs, then I noticed there was no room for a wrench or puller of any kind between the stud and the "ledge" on the bottom inboard side of the head. So now what? How to you R&R those studs? An obvious solution would be to weld a barrel nut to the stud but this is pretty final; if it doesn't work there's no going back.

So what's the most economical and expedient solution to this? Thin flange cat HE's available? Special removal tool or technique that works? I'm open.

I should point out here that I currently have on hand two complete cat exhaust systems, thick flange, plus the pre '73 that was on the car when I bought it. I also have both sizes of CIS on hand (not that I'm going to use them complete; I'm going back Tbitz). So I can mix and match a lot myself, but the heads are the missing link. Then there's the obvious solution of going to Antique tags and bypassing the whole thing, But that's the last resort.

[Steam Driver]

Later -

I decided to try removing the ones I could get to first and see how difficult it would be and amazingly, after soaking in Kroil, all six turned out easily. So I had a go at the others with the classic double-nut routine. This worked good on five of the six, but one wouldn't budge (isn't that always the case?). So I hit it with the MAPP gas torch until it was red, let it cool off some, hit it with Kroil and the double-nuts, and out it came. So the heads are more or less ready to accept the longer studs. Only a couple of the twelve studs appeared to have any thread locker on them, and a couple of them appeared to be homemade out of bolts with the head cut off.

I came across another "hit it with a bigger hammer" mechanic's solution while doing this. With only a couple of exceptions the studs were all bent, some slightly, some a lot, in the outboard (i.e. spreading) direction, like the HE's fitted wouldn't quite fit, that the hole spacing in the flanges was wrong. This doesn't seem right to me, but that's the way they were. If anything you would expect the hole spacing in the earlier flanges to be closer together than the later ones. But I think they've all been the same. So I don't know what might have been going on there.

Anyway all the old studs are now out and inthe trash.

[fred cook]

Originally Posted by Steam Driver

Later -

So I hit it with the MAPP gas torch until it was red, let it cool off some, hit it with Kroil and the double-nuts, and out it came.

.

The next time you need to remove a stud, heat the head or block that it is screwed into rather than the stud itself. By heating the block or head, you are causing the aluminum to expand slightly and melting any thread locker. You don't have to get anything "red" hot, just warm enough to be uncomfortable to touch. I found that the best place to heat was inside the port or spigot next to where the stud is threaded into the block or head. Heating the stud to "red" condition will just weaken it, making it more likely that it will snap off flush.

[Steam Driver]

Ordinarily that is how you would do it (that's what I did for the case studs) but the heat-disappating design of the head makes that a little difficult. What you do by heating the stud is you make it expand in the hole, breaking the corrosion bond.

I work at a railroad museum. This is a technique we use for removing boiler studs from steam locomotives. Parts are a little bigger though.

[jjeffries]

Who can argue with the man who fixes steam engines? Good stuff! Sir Isembard Kingdom Brunel would approve. John in CT