My 621 bellhousing has a 2" crack at the bottom. I was wondering if anybody has had any luck with getting one welded up.

I found a used one for $300 :cool: and can get a repo for $160.

thanks

First of all, can you post a picture for a better assessment?
Second, I've had MANY alum bell housings welded in various areas of the housing with zero problems. If it is on the BOTTOM, for sure, no worry. Remember, the early bell housings were ALL the open bottom version. If the crack is BELOW the line of the lower bolt holes which attach the housing to the rear of the block and below the 4 holes which attach the tranny to the bell housing, then there is nothing to worry about.
If it were my housing, I'd have it welded (inside and out), grind down the welded area, work the grinding marks down with a die grinder and a buffing pad (Scotchbrite pad) and then VERY lightly blast it to even up the final finish.

I've welded several aluminum bellhousings myself and they come out well.

My 621 had a hole where someone tried to bolt the alumnium head starter and it was about the size of the bottom of a soda can right in the arc that runs back from the starter. We melted down some alumnium and cast a patch. Then we hand grinded it to fit the hole. Then we tigged it into the hole. I then hand grinded the arc back smooth inside and out. Painted it orange and you can't tell it and its holding up great.http://www.chevelles.com/forums/attachment.php?attachmentid=26466&stc=1&d=1263581731

Thanks. That puts my mind at ease a bit.

Here's a couple of pics. The hairline cracks in the second pic aren't through. I don't know if they're cracks or just a poor casting. Should I get them welded up at the same time?

The one in the bottom is a crack. The others are not. I have a very good 621 bellhouisng and it has the same casting lines in it. They look like cracks, but they aren't. Just weld the one in the bottom.

Thanks Freddie

Yep, I also believe that is just a casting line in the second picture. That's fairly common. If it were a crack, it would also be on the outside of the housing.

My brother had the cracked bell housing on his TH350 welded last year, and he hasn't had anymore problems with it. So I think you'll be ok.

Seems like several of these crack in that area. Once rewelded they seem to be OK with the stress relieved. Drill a 1/8" hole at the very end of the crack to stop the spread and then reweld.

All this talk on welding.... But what grade aluminum is the base metal and what is the filler material being used to make these welds?

4043 wire should be used to weld cast aluminum.

4043 wire should be used to weld cast aluminum.

Thanks.