Exhaust Stud Replacement
06-29-2014, 11:25 AM
#1
Racer
Thread Starter
Join Date: Aug 2012
Location: Hixson, TN
Posts: 300
Likes: 0
Received 0 Likes
on
0 Posts
Exhaust Stud Replacement
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.
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.
06-29-2014, 11:45 AM
#2
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
The early SC's had thin flanges and cats. At least through 1979, maybe 1980 as well. So those would fit.
(Correction: Only through 1979. When they dropped the air pump and added an O2 sensor in 1980, they went to the thick flanges.)
I had a similar problem. I found a nice pair of used heat exchangers, but they were thick flange. I decided that trying to remove all the studs would just lead to disaster (I had the engine on a stand, but no plans to disassemble).
I ended up using a Sawzall to cut the flanges so they were thin enough to fit over the studs. My used exchangers also had a lip on them that protruded into the exhaust port. I think this means they were from a 3.2. I had to use a Dremel to cut that lip off as well.
Mark
(Correction: Only through 1979. When they dropped the air pump and added an O2 sensor in 1980, they went to the thick flanges.)
I had a similar problem. I found a nice pair of used heat exchangers, but they were thick flange. I decided that trying to remove all the studs would just lead to disaster (I had the engine on a stand, but no plans to disassemble).
I ended up using a Sawzall to cut the flanges so they were thin enough to fit over the studs. My used exchangers also had a lip on them that protruded into the exhaust port. I think this means they were from a 3.2. I had to use a Dremel to cut that lip off as well.
Mark
06-29-2014, 01:22 PM
#3
Racer
Thread Starter
Join Date: Aug 2012
Location: Hixson, TN
Posts: 300
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for the information. I'll keep all that on file. I have access to a Sawzall, but boy that would be a lot of work!
It turned out to be a non-issue. I to try the ones I could get to first to see how they would remove and amazingly, after soaking in Kroil, they turned out to be pretty easy to turn. With those out I had a go at the others with the classic double-nut routine. This worked good also on five of the six, but one wouldn't budge (isn't that always the case?). So I hit that one with the MAPP gas torch until it was red, let it cool off some, hit it with more 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 studs appeared to have any kind of thread locker on them.
I came across another "hit it with a bigger hammer" mechanic's solution while doing this though. 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, if anything. But I think they've all been the same. So I don't know what might have been going on there, other than a crude solution to a problem from a guy who has a reputation for doing good work.
Anyway all the old studs (including a couple that may have been homemade out of bolts) are now out and in the trash.
It turned out to be a non-issue. I to try the ones I could get to first to see how they would remove and amazingly, after soaking in Kroil, they turned out to be pretty easy to turn. With those out I had a go at the others with the classic double-nut routine. This worked good also on five of the six, but one wouldn't budge (isn't that always the case?). So I hit that one with the MAPP gas torch until it was red, let it cool off some, hit it with more 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 studs appeared to have any kind of thread locker on them.
I came across another "hit it with a bigger hammer" mechanic's solution while doing this though. 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, if anything. But I think they've all been the same. So I don't know what might have been going on there, other than a crude solution to a problem from a guy who has a reputation for doing good work.
Anyway all the old studs (including a couple that may have been homemade out of bolts) are now out and in the trash.