So, how do you weld up a cracked block???? I just found a crack in my 429 in between the engine and tranny. Can I weld the crack or do I need to get another block? If I need a block, can anyone tell me where I can buy just the block? The engine was out of a 1968 Thunderbird. I know the 429 block is the same as a 460. I want to buy just a block.

 

although you can weld up the crack, it is expensive and not for the backyard welder to try and do. the block needs to be heated up and the crack needs to be brazed. takes decent skill to accomplish as you can make it worse by not doing it properly.

the 429/460 blocks are too cheap and plentiful to even bother doing that. check with your local engine rebuilders as they usually sell block cores for pretty cheap (picked up a 302 block for $80 locally).

another source is your local wrecking yards. you could probably pick up a complete 460 engine for $200 - $400. if you pick up a 460, would be a good time to rebuild that 460 and drop it in your car and tell everyone you still have the 429 under the hood. no one will ever be able to tell the difference.

Rgds
Mike

 

hastalloy rod. mine cracked in the samed spot in the water jacket just pre heat it to run the moisture out of the area and weld it up. that is if you have enough skill with the welder.

 

Thanks, I will look for a different block.... maybe someone can answer this...
I have a 4U crank and would like to use it in the next block. Can I put the 4U crank
ina D9TE-AB block? I can get a great deal on the block but it is bare.. no other internal parts.

 

This sounds like a great time to upgrade to a 460. You can reuse your same heads if you want too. You are most likley going to get the guts with the block anyway.

 

I have read somewhere that the rotating assy from your early casting will not fit into the D9TE. I think because the early casts were internaly balanced and the D9 is external, but I'm not a pro. If it matter i think you can use the D9 in the early casts. I'm pretty much looking at the same set up as you are and if your looking of a new block anyway, I'd look for the early 460 and get the extra cubes.

 

Seans, yes you are right. From the SME's on this site I can not use my rotating assm. in a later model D9TE. They put me straight. Great info and great guys. SO Iam looking for a 68 (C8XX) to a 78 (D1XX) for my replacement. Going to the YARD tomorrow to try and see if we can ****** one.

 

hmmm so you just heat it up and weld it with normal iron welding?

 

i know what won't work. JB weld. it doenst work for anything!
Those who disagree are fooling themselves, or used it where scotch tape would fix the problem.

 

What would you use to heat the block up with? I don't have anything big to do this.
All I have are small heat sources. How hot do you need to do a good job?

 

I used to weld a lot of cast iron when I was a millwright. To do it right I would completly strip the block. I would remove the cam bearings as the heat involved is going to ruin them. You will want to scrub out all the oil galleys before and after to get all the baked gunk out. Do all the crack prep before you heat it. With various grinders you need to grind the cracks all the way out and drill holes at the ends of the crack to terminate it. All grease & paint needs to be removed near where you are welding. A block is so big it's not recommended to just heat up one small area or you will cause more cracks. The idea is to not shock it. You want to heat it up slow and bring it down much slower. On a block I would try to take 24 hours to bring it down. To start it should soak in an oven at 350 degrees for a few hours. If no oven is available I like to use a big propane burner like they use to heat asphault. You want to heat it up real even so don't put it right on the part. Acetylene is to hot so if you are using a regular rosebud stay way back. Then wrapped in insulation while you weld it up with a good rod that is designed for what you are welding on. Some of the stuff I used to use was $8 a rod back in the 80's. Back then I used a stick on thermometer and never let the area near the weld go over 380-400 max. Now days I have a Raytek temp gun like this
When it starts getting too hot I just cover it up with the insulation and wait until the area is back to 350 then continue. Once welded up and cooled in a controlled manner. You don't have to get really fancy. I used to just wrap it up good in a couple layers of house insulation and keep it in a enclosed area like the shop where it was welded. Once cooled I always liked to grind it back to flush and use a die grinder to chatter around the whole area to restore the surface back to a finish it used to be. This helps keep stress away from the joint. Then run a dye penetrate test to be sure it is water tight. Done properly welding cast iron can work out really well. We usually only did it on stuff that couldn't be replaced due to cost or availability. I have put the ears back on a bunch of Ford Top Loader cases and they are all still holding as far as I know..

If you were just sealing up a water jacket you could braze it but I would still preheat the whole part to minimize the shock. Brazing a cold part requires bringing the area red hot and that can cause even more cracks.

Personally I would never weld on a 385 series block because they are so plentiful.

 

Hired Gun, thanks for the detailed aproach to welding this block. I understand and
maybe your last line is what I will do. Getting a different block seems to be the best way to go. I might just try the technique you described just to get the experience on cast iron. The block is too far gone and the crack is about 4 inches or so long. Just don't want to be in tim-buck-too and have the weld go south.. would be just my luck ya know.