My intake cracked at the heater port nipple. When removing the old rusted nipple the intake cracked down 2 sides around the heater nipple inlet. Was wondering if anyone has welded these intakes before? I have a good friend who is an engineer/machinist, he can definetly weld it, his only concern was that some cast aluminum doesn't weld good and wasn't sure about that. He hasn't seen the intake yet, going to pick it up Sunday, but it would be nice to know others have welded them with good results. He is used to working with new metal/aluminum, so it's not his typical work and wasn't sure about the quality of cast aluminum that was used back then, but if it can be done im sure he can do it. The nipple took out about the top 1/8 to 3/16 inch of threads, but I was thinking about milling it down an 1/8" and getting into new threads. I will run a pipe tap down the threads before reinstall. Just looking for input or if anyone has any other thoughts. Not a good day.

 

I've had a stock 4bbl al Corvette/GM manifold welded with good results.
With yours being polished, you'll never see the repair after you grind down the weld and polish.

 

That'll weld right up. Just use teflon tape and don't tighten fitting too enthusiastically.

 

With any luck, a good welder could put a dummy plug in that boss (loose), notch the cracked areas and heli-arc it back together. Grind down any excess, wire brush it and it should be good to go.

If you can tape/plug it and use a vise-grip to keep it together, drive it to the welder.

 

Just keep in mind that is a pipe thread. Pipe is a tapered thread. The harder you tighten it more it spreads the outer thread. The farther in you tap it the bigger the diameter the thread.

 

Correct! The more you tighten a pipe plug (especially in aluminum), the more you risk cracking the part. If a pipe thread is leaking, it is best to remove the part screwed into it and clean/chase the threads; then use a good pipe sealant (NOT silicone-based) and reassemble the part without using very much torque. If the threads are clean and you use proper sealant, tightening the part till SNUG and letting the sealant set up is all you should need to do.

In the OP's instance, the boss broke taking the 'frozen' part out of the pipe thread. [unusual, but it can happen]

 

I feel much better about the situation, still not happy, but at least it can be fixed. Thanks everyone for all the input.

 

You can 'heal' the cracked boss; but you will still have some remnants of the cracks in the pipe threads inside that boss. You just need to pack some pipe dope into those cracked areas before you install whatever fitting goes there. That should seal any leakage.

 

Any recommendations on a good thread sealant? I normally use locktite pst592 paste.

 

Are you trying to the manifold as original as possible? It not. I'd cut it off and weld on a new npt bung. I would also bolt the manifold to something solid so as not to warp it from the heat of welding.

 

This seems to be the manifold that just keeps giving, while removing the thermostat housing I could tell the bolts were not going to come out. I tried everything I could think of to try to get them out, but in the end they just broke off. My thoughts are to either try and put the manifold in something solid that can precisely and slowly drill out the old bolts. Then either retap them to a bigger size if possible, and not too large for the thermostat housing, or maybe rethread them with a helicoil, or just try and drill and tap them to the original size and see if it looks like it would work? My other idea was to chamfer the edges of what's left of the bolts, and weld a short length of bolt back to them. Making them a stud and use a nut on top of the thermostat housing.
The other thing I noticed was the ceiling of the intake in the water jacket ports by the thermostat are getting very thin in a couple spots, and where the gasket seals is somewhat corroded away.
I really didn't want to buy a new intake because they are so expensive, not sure what to do. The car is fairly original, so I either want to use this intake, or if I have to, go back with the correct casting numbers intake. The ones I've seen were also used and I might not be getting anything much better than what I have. Just not a great scenario.

 

Heat the aluminum with a propane torch right where the bolts go in. Let cool. Repeat. Now work back and forth with vice grips and WD. Next after that. Weld a nut onto the shorter stud. The heat from welding should break bolt loose. If that works, cut the other same height and do it again. Worst case grind flush, center punch and drill carefully. Once you get hole big enough, you will cut into the threads and the bolt can be picked and fought out of the alumi um threads. Usually. Those bolts are old soft steel. But not as soft as aluminum...

 

I agree...heating up the aluminum...but I use wax so it can get down into the threads in most cases.

In this type of scenario you have dissimilar metals...thus possible corrosion. Hence...they are really seized.

Do you know what an EDM machine is??? I have one and it can burn out broken drill bits, taps and bolts. And not damage the surrounding metals.

I am quite aware of your problem because I dealt with the same scenario on a tri-power intake for a 1967 with A.I.R. Lucky for me I could drill and install heli-coils and make it work again.

I use many products from Muggy Weld. And I can say...they ALL do as they cay they can. These products from Muggy Weld have saved my backside more times that I can to count.

Check this out:
https://www.muggyweld.com/video/cast...nifold-repair/

So... your concerns about the thin spot can actually be filled in with the correct rod and flux.

DUB

 

Shouldn't be any problem, we do similar repairs all the time for our 100% stock-appearing restos.

The welding on new or old aluminum makes little difference, some weld easily some need a bit more attention!

Looks as though that intake was "polished", would have to address that also.

Thanks, Gary in N.Y.

P.S. Here's a little "tip" for re-tapping, use ONLY a pipe tap with an "interrupted" thread, makes tapping a "walk-in-the-park", DO NOT use a conventional pipe tap on aluminum?

 

good advice

you are lucky in one way/
alum can be built up where ever you want.
cast iron, not so much.

that sux your mani is in need of repair.

 

Another way to remove the broken bolts would be to drill a hole down threw the center. Then heat the bolt try to get it as hot as you can with out melting the Aluminum. Then just walk away and let them cool. Metal shrinks when heated and cooled. You will now have a bolt that is smaller in diameter than what it was originally. Use your favorite lubricant and they should now just walk right out. If the threads are messed up I would helicoil them. Nobody will ever know they are there and it will be stronger than new.

 

I appreciate all the good advice. I think with some of these methods we can get it back in good shape and save it still, I was alittle worried at first. This forum has been very helpful again. If this is something you do and know you can fix these issues would you PM me. If my friend doesn't feel comfortable doing the repairs I will need to send it somewhere and pay to have it repaired. I could get the bolts out most likely, but the other things I cannot. So who ever fixes it I will let handle the bolts as well, they most likely have better tools to take care of it then me if they won't come out with just heat and penetrating oil.