In my experience, Terry, is that cast iron needs to be pre-heated to achieve a decent weld.  Then there is the dissimilar metal situation and I have no idea how to handle that.  Chevy's being as common as they are, it might be a better, and stronger, solution to replace the block, especially if the the engine needs to be pulled and or disassembled anyway.  Lot of work but...there you are.
See ya soon,

BB1
 

Last edited by Bullet Bob (7/20/2022 7:24 PM)

Chevy starters use a special knurled bolt to attach them.  Without the knurl, the starter is not properly secured, which is probably why the block is broken to begin with. That said, a standard bolt might not do the job, but obviously would be better than what is there now!
I can’t advise on the welding process, but if I were to attempt a repair, I would try to get it so it had a threaded hole like it originally had so the correct bolt could be installed.

To avoid a threaded hole being able to induce forces on the new joint that would tend to force it apart, a threaded tube of at least 1/2” od could be welded in that would contain the forces trying to separate a joint right through the threads. Envision an internally threaded 1/2” od, or larger, steel rod, or tube, welded in place. I am not sure if there is physically room for that, but it would be the strongest repair.

Best fix:  another block. It is just a chevy so they are cheap and plentiful, and if it has to come out for repair anyways, hey… an LS swap is in his future.

Surely there is a fix for this already out there?

Or… WWTKOD?

Billy its a 396.

Ok....I believe I have your solution.  Non welding AND non engine removal.

There is a transmission adaptor plate for early Chevys to put a modern transmission in.   Early engines did not bolt to the block, but to the bell housing by three bolts, like Fords do.   

So use this adapter plate and an early starter.  Trick in this is finding an early starter.   

Danchuck company will be who you want to look up.  Summit racing has them, but we shy away from links here.   Google 55 Chevy starter adapter plate.

Ah, nevermind..I reread and see you know about the plate.  Lol

Last edited by Greg B (7/21/2022 9:55 AM)

Greg B wrote:

Ok....I believe I have your solution. Non welding AND non engine removal.

There is a transmission adaptor plate for early Chevys to put a modern transmission in. Early engines did not bolt to the block, but to the bell housing by three bolts, like Fords do.

So use this adapter plate and an early starter. Trick in this is finding an early starter.

Danchuck company will be who you want to look up. Summit racing has them, but we shy away from links here. Google 55 Chevy starter adapter plate.

Ah, nevermind..I reread and see you know about the plate. Lol

Thanks for the info Greg!!  I'm trying to convince him to go the route of the plate!!  The starters are readily available.  I tried to tell him that you run a risk of damaging the car pulling the engine out and replacing it!!  Worse thing installing that plate is if you drop the trans off the lift!!

I APPRECIATE ALL THE SUGGESTIONS!!!

Google says
Can I braze cast iron to steel?  Steel can be braze welded to cast iron.  However, the joining of dissimilar metals by any welding process is something to be approached cautiously.

I see it is an automatic, if it was a standard, i would tell him to park on a hill.
 

Last edited by Alan (7/21/2022 4:20 PM)

Bullet Bob wrote:

I keep thinking that a guy might be able to clean up the broken area on the block and make a flat piece with a 3/8" stud...as you were talking about...that has a flat surface above the stud that attaches to the block with a 5/16 grade 8 bolt at 90 degrees to the stud.  But that would also require the removal of the engine to flatten the surface and drill tap the 5/16 hole into the block. 
No easy way on this one.
Pulling the engine is NOT a sure fire path to body/paint damage.  Since we put it back on the road in 2015 I've had the engine out and in at least twice....don't ask, let's not get into that....Ok?
But no paint/body damage resulted, just gotta be careful.
 

I agree that you gotta be careful,  I believe they call that risk assessment.  I tend to over analyze situations but never regretted it!

TKOPerformance wrote:

It can be repaired.  I've welded cat iron successfully before.  However, the engine needs to come out and needs to be disassembled so the block can be cleaned thoroughly.  The key to a successful weld is cleanliness.  Hot tanking followed by baking is the best method.  Ideally you then heat the block up to about 350 degrees prior to welding.  You need a specific rod that's mostly nickel to make the weld.  I stick weld cast iron because the proper rods are available at Tractor Supply.  Welding it is nothing special technique wise.  You may get some sputtering, popping, etc.  Cast is porous and sometimes there is entrapped oxygen, hydrogen, etc. that pops as you heat it to a molten state.  Let the weld cool, then ideally heat cycle the block to remove trapped stress from the welding (heat it up to 350, let it cool, etc).  My advice with the break being through a bolt hole would be to weld the hole up, then mill the starter pad flat again and drill and tap the hole.

If all that sounds like a lot of work; it is.  I think I would only bother if the engine was the correct engine (numbers matching) for the car.  Otherwise, find a used 454 and build it close to LS6 specs (I'd use a roller cam).  I built a pair of 454s like that for a 29' Scarab my family had when I was a kid.  She ran close to 90 with the right props.  My Dad also had a '69 Chevelle with an LS6 (you used to be able to buy them as a crate engine) that ran 10s in the 1/4.  That may have actually been the first car I worked on now that I think of it.  The BBC is a beast.  They've been mostly supplanted in Chevy circles now by the LS series engines, but for decades they were the only way to make serious power because the canted valve heads breathed so well. 
 

And there is your answer as to…. WWTKOD???