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TR4/4A wobbly exhaust manifold studs

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Dash

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I had to replace all 3 stud bolts on the exhaust manifold, the threads were not salvageable. Well of course over time the studs had pretty much welded themselves in and after trying many options, the only one left to was to drill them out. Managed to get as close to center of each that I could and after almost a day of step drilling, finally had daylight all the way through. I had gotten new studs from moss which are 3/8 unc (16 thread count) so cleaned the hole with a 5/16 bit to re-tap. It was one of those ahaa moments when you think ok, finally getting somewhere BUT apparently the holes are a teeny tiny bit out of round and two of the studs are a bit wobbly and I'm not convinced they are getting a strong enough bite.
What I would really like to do is fill the holes by welding and then redrill but I read where welding cast iron is tricky business.
Sorry for the long explanation to get to my question but since there are some threads that may create a good bite for jb weld what do ya think about smearing someof that in the holes then redrill? Wouldn't take much of it but do ya think the cycles of extreme heat and cool down would create problems?
 
Dash, I have used a longer stud and topped it with a nut on the top side. You might have to cut the nut in half in one place, just thread it on through and into the nut. That will hold it with the big brass nut on the bottom. If you heat it too red, brazing would work.

Wayne
 
Hi,

I installed two Helicoil's in the exhaust side of my cylinder head (TR-4a). If you drill it out and nick the water passage, put a little thread sealant on the fastener. BTW, a LH drill bit works great for removing broken studs.


RG
 
The book solution is to heli-coil the bad holes.

Welding old cast exhaust manifolds will absolutely NOT work. The cycles of heating above the transition temp while the manifold is in use changes the metal composition. The free carbon turns to graphite and is no longer weldable. If you can get the weld to stick, it will be rock hard when trying to cut new threads.

Before you devote too much time, realize you can find used manifolds readily and cheaply. Personally, I'd invest in a heli-coil kit, and if that goes south just replace the manifold.
 
Thanks to all for the advice... a more careful inspection revealed there is still a little of the old stud remnants still in at least one of the holes even after all that drilling and re-taping so I should just go ahead and use the longer bolt w/nut option but I'm sometimes a stubborn hard head when when it comes to keeping some things as close to original as possible even if no one but me would ever know the difference and this is a prime example. It's a stupid self inflicted aggravating curse for sure! Anyway, I'm hoping using the 25/64 bit for the helicoil with clean it up and leave enough bite for the insert. If not, well then bolt w/nut it will be. I eventually may wanna install headers but its a new overhaul that's back on the chassis (body still off) and, for now, my primary mission is to get everything outside the block reassembled using as many original parts as possible. The goal being to at least start it to check for potential issues before I get carried away investing in parts I can do without if that makes any sense.
 
Dash, I will look in he warehouse were I have a few TR parts and if what you need is there, I'll donate it to your OCD. LOL You will have to come get it.
I'll let you know tomorrow.
Wayne
 
I read this with interest as I have an exhaust manifold sitting in the shop needing the three studs to be replaced. I like the idea of using a bolt and nut---but what about welding a glob on the end of the bolt in place of the nut? I am thinking that there is little room for the nut without cutting out room for it.
Charley
 
If it's a 4A manifold they are getting hard to find and expensive when you do find one. The Heli-coil sounds like a good solution.
 
Ditto on the Helicoils, they are relatively inexpensive, easy and last a long time, perhaps longer than the original threads. Tom
 
Dash, Sorry to say no TR4 exhaust but I did find the dimmer switch I needed for the Spit6 I'm building. So not a total lost trip.
There were a lot of small chrome bits, if you need any of those type things.

Wayne
 
Thanks Wayne for checking..seems like every inch of this project wants to fight me tooth and nail so haven't gotten to the glitter pieces yet. I will check back with ya though when I manage to get that far. However I am dissapointed you didn't find a decent tr4 body when you were rumaging in your warehouse though..lol
BTW, the manifold is gonna turn out ok..helicoil working out fine..the block side was a little rough so took it to the machine shop to have it skimmed
Dave
 
Dave, Had a bunch of body parts a few years back, TR4A and 6, but a crack head wiped out all of it, along with all the scaffolding used in construction.
He might have got $3 for the fenders and hoods each.
Still have a couple of transmissions. Have a guy coming from Florida for interior parts next month, his is real bad.
Let me know if I can help.

Wayne
 
Wayne, a long way to go before I'm ready for it but I know I'll need a heater housing eventually..I have a good core and fan etc.
Oh , had a roofer here a couple weeks ago and the guy recognized the tr4 right off the bat. As luck would have it, he said his father had a tr4a and it has been in his warehouse for 30+ years. Well goes without saying I started paying attention! He said the engine was blown but the rest was in good shape. Not sure of his definition of "good shape" but aparrently it's buried in there and hard to get to at the moment but he said he would call so I could come look at it. If it really is in decent shape and I can talk him out of it, I may be switching projects. May as well lock me in a rubber room now and throw away the key, I've obviously lost my mind!!


Dave
 
Best of British lucky laddie.You must not be married or like me, have a wife that wants them all. Oh. you can fix that, she says.

Wayne
 
Note the description of the missing / cut off tab on the eBay part.
Charley
 
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