Help! 360/4-speed conversion in crisis!

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JoshDuster

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Hello, I recently inherited a 1970 Plymouth Duster that was in the middle of a conversion from a slant 6/automatic to a 360/4-speed. The 360 is a LA block. The engine and transmission are in place and much of the work so far has been forensic. My dad was a capable mechanic but this particular project had been shelved about 10 years before I got my hands on it. I was installing a new starter so I could begin putting on headers and exhaust. While doing so I noticed one of the bolt tabs attaching the block and bell housing had snapped off during installation. Upon further investigation I actually found the tab itself in the many boxes of random parts that came with the car. I’m a sheet metal worker by trade and a pretty decent tig welder. I know how difficult a job welding this tab back on can be. Question is: is that my only option in an attempt to repair this issue? Is it even worth a go with how finicky cast iron can be? How common is this issue when attaching a transmission? Most resources I’ve seen that have addressed this have been on aluminum blocks and bell housing. It’s getting harder to find a built LA short block and starting from scratch would be very expensive. What can I do from here?
 
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Can we get a picture of exactly which "tab" is broken? That would better equip us to be able to answer.
 
I know exactly how its broke. A dyno shop broke both sides on my block. Very easy to weld on. . V the seam slightly, then heat the block and the piece slightly . Weld it with Certanium rods. The first pass will look like bubble gum. The second pass will be as smooth as glass. I welded both sides back on that were broke. I bolted the block to an old trans and welded the front sides first. Mine were broke off through the pins from the dyno shop trying to hammer the pins front like you can do on a Chevy. The rods are idiot proof very easy to use
https://www.lawsonproducts.com/Certanium/889-Cast-Iron-Stick-Rod-Electrode-532/P12006.lp
 
Here’s the location

B7BEFCE2-58EE-4424-AEA9-BFF0586AC817.jpeg


2688E861-68FA-4D86-A1C6-4A97ADE8EFC6.jpeg
 
That could be welded fairly easily. But I would do it with the engine out of the car and bolted to a spare trans bellhousing. Like @Oldmanmopar said, needs to be stick welded, (never used the electrodes he posted but they are interesting to me), I’ve used nirod in the past on cast iron with good results. Bevel the crack, Heat the part, weld it, and control the cooling process. Do not let it cool quickly and you should have a good repair.
 
I once broke an ear off of 440 from the starter mount location....just like oldmanmopar said heat area first and should go smoothly...
 
I'm just askin here.......why does it need to be welded back on? I mean......."how" important is it?
 
Certanium Alloys makes an arc welding rod specifically for cast iron, a roommate of mine from back in the late '70's demonstrated and sold it.
 
RustyRatRod said:
I'm just askin here.......why does it need to be welded back on? I mean......."how" important is it?
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That was another question I had but it sounds like an easy enough fix from where the project sits. Better pull the motor now before burying it buttoning up the top end. Thanks guys! This is a pretty helpful group so far!
 
JoshDuster said:
That was another question I had but it sounds like an easy enough fix from where the project sits. Better pull the motor now before burying it buttoning up the top end. Thanks guys! This is a pretty helpful group so far!
Click to expand...

I agree. IF you're gonna fix it, now's the time for sure.
 
don't worry in my youth I was in a hurry switching from a auto to 4 speed and did the same thing /never had a problem just make sure the input shaft doesn't bottom in the back of crank. also get a dow pin and put it in the trans the block will rest on it and wont move after the bolts are tight. also your oil filter threads look striped on rusted you might want to take a look at it
 
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if you're at all worried about the strength of a repair you can add a 'stay' bracket afterwards from that bolt down to a couple of the lower bellhousing bolts to give it added support. i've done that in the past.
neil..
 
JoshDuster said:
Here’s the location

View attachment 1715745881

View attachment 1715745883
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Looks exactly like mine. They hammered the pin front or tried to bolt it to a trans or bell without it against the trans. Put the pin in the block hole and remember its stepped. After in place weld it but not the pin remove the pin and finish the weld. Well the break to the hole and clean the weld close to size with a die grinder then ream it the rest of the way with the proper reamer. Not a drill! apply JB weld to the pin when done and push it back in.
 
RustyRatRod said:
I'm just askin here.......why does it need to be welded back on? I mean......."how" important is it?
Click to expand...
The hole that is broke in half is the dowel pin hole. It is used to align. Center to center motor to trans. Whenever you install a different trans on a motor or vise versa. You should always indicate the trans or bell. Brewers sells offset dowels to correct the alignment. It is a must for proper wear on mains and pump bushing or input bearing on a 4 speed. Makes a big difference in performance.
Good blow proof bells come with oversize dowel holes . You indicate the bell, Tighten all bolts then weld the thick dowel washers in place that are provided with the bell. This is a must or premature wear and loss of power wil result.

When ever you change the trans or factory bell buy the offset dowels and do it right.
Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists
 
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Oldmanmopar said:
The hole that is broke in half is the dowel pin hole. It is used to align. Center to center motor to trans. Whenever you install a different trans on a motor or vise versa. You should always indicate the trans or bell. Brewers sells offset dowels to correct the alignment. It is a must for proper wear on mains and pump bushing or input bearing on a 4 speed. Makes a big difference in performance.
Good blow proof bells come with oversize dowel holes . You indicate the bell, Tighten all bolts then weld the thick dowel washers in place that are provided with the bell. This is a must or premature wear and loss of power wil result.

When ever you change the trans or factory bell by the offset dowels and do it right.
Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists
Click to expand...

I went back for a second look after I said that and saw it. It is a tad important. lol
 
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