Another welding thread, Cast iron

great thread keep it going! this get my mind racing for more data!

 

This is the thought of one of the real welders that I talked to about welding exhaust manifolds. He thought that the carbon content is less from the constant heating. Especially on work engines that occasionally glow from the exhaust heat. And modern engines with EGR and retarded timing.

 

This is what I'm talking about. Just get in and do the job. You can talk the thing to death. It can be done a lot of different ways. It isn't rocket science. I would hire people and fire them because they didn't know how to do the job anyway, and then I would get in and do it myself. JMHO


'' A hot rod that is unsafe is junk, simple as that. ''

 

Tig silicon bronze is the ticket, some pre and post heat does not hurt.

 

I've heard that from others too. Probably a pretty good idea!

-Brad

 

I've watched the process done specifically on freeze cracks on 409 blocks. As you probably know, they're thin where the deck meets the outside wall of the block, and frequently crack there. They also frequently crack between the freeze plugs.

Considering his reputation in building engines and high-end restorations, and my 15 years of going to shops and watching how people do things, I'm more than comfortable in saying he's doing it the right way, and rare blocks are being saved--and being saved with a better method--than heating the block in a furnace.

I took exception with your post because you used the words "mig" and 348 block, which was close enough to my example as to dismiss it... even though it's nowhere near the same as what I was talking about.

As for the rear ends--they are plug welded. There are holes in the casting where the mild steel tubes press in, and they are plug welded.
Those plug welds, even from the factory, OFTEN fail. Its common with GM 12-bolts, Dana 44 and Dana 66 rear ends.

In that case, the wire alloy cools at a different rate than the cast, and as it cools it pulls away from the cast. That that point, the plug weld simply becomes spline or woodruff key (in effect). The wire that rear end builder uses "keeps flowing" (for lack of a better description) and has enough elasticity while it is cooling that it doesn't pull away from the cast or mild steel while each is cooling at a separate rate. The result is good penetration in both metals, with a solid weld fillet at the union where the tube presses into the housing.

Again... over 30 years of doing it, on high-end, high-horse builds on everything from TF cars to rock crawlers and monster trucks... but it can't be done, especially with a MIG.

-Brad