Gerry
Toyota Fan
AKA" lisasdecals
Posts: 55
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Post by Gerry on Mar 4, 2007 21:29:33 GMT -8
Two of the 4 threaded holes on my Corona's 3RC manifold broke off . Can I take this to a machine shop and have them weld the area where it broke?
Any help would be appreciated.
GR
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Post by Carlyn Dinkler on Mar 5, 2007 3:32:06 GMT -8
I believe that welding cast iron parts like a head or manifold requires a special technique, so the chance of making the manifold as good as new are poor.
To refurbish a Corona 3R# or the later 8/18RC manifold assemblies requires a great deal of work. Normally in separating the intake and exhaust manifolds, you will break several of the (four) bolts. I normally drill these out and put HeliCoils in because I have broken too many taps trying to chase the original threads. Most of the time you can remove the studs to the exhaust pipe with a stud remover and carefully chase the threads. The case iron tends to be case hardened because of the heating/cooling cycles so use oil and a gentle touch. If you break a tap in a hole, one technique is to use a center punch to break the tap, which is hard & brittle, into small pieces to remove. Remove all the plugs & carburetor studs (double nut technique works well on these), blast & paint the exhaust manifold, and glass bead & clear coat the aluminum intake manifold. If you removed the choke stove tube, replace with new ferrules & new or replated hardware. Assemble the intake manifold to the exhaust manifold with a new gasket & new harder bolts. I like to mount the manifold to a head or engine, with the bolts to the head not tight, before I tighten the four bolts holding the manifolds together to assure alignment. Next, take the assembly to the machine shop to mill the mounting surface to the head. To finish, replace all the studs for carburetor & exhaust pipe and all plugs with new or replated ones.
I have one late Corona 3RC refurbished manifold ready to ship $225 + shipping. I am out of 8/18RC refurbished manifolds. These are not fun to do, so I do not work on them very often.
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Gerry
Toyota Fan
AKA" lisasdecals
Posts: 55
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Post by Gerry on Mar 20, 2007 21:05:05 GMT -8
Thanks for the info. I talked to my friend( he welds bridges and heavy equipment) and told me to take it to him. I took it to his shop and he was able to fix it! Good as new!!!
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Post by 79corona on May 25, 2007 4:33:12 GMT -8
Exhaust manifolds can be welded, actually it's more like brazing. But you have to know what you're doing. I had one done by a guy who owns a machine shop and works on diesels. Apparently he heated the manifold prior to welding, and had over 30 years experience. So far the weld is holding. The crack was between the two middle ports. When I receive my new muffler assembly I'm take the manifold off and reinstall the hot air intake cover that surrounds it. I'm replacing the entire exhaust system from manifold on back.
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