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Block welding question ?

Discussion in 'The Hokey Ass Message Board' started by mopar210, Mar 11, 2012.

  1. mopar210
    Joined: May 18, 2008
    Posts: 392


    this may be a dumb question - but . has anyone ever tried welding an engine block/deck surface ? i have a big block RB mopar and the prev. owner stuffed it full of nitros and smoked a head gasket and cracked the head , in turn this dug a "ditch" between 3 & 5 cylinders . can it be mig welded then file it flat ? i saw a clip on you tube of a guy doing it in the car and it worked ! at least he said it did . i want to the complete motor with very little machine shop "time" , i beleive that all my measurments so far look very good and the motor had very few passes on it . it has all good stuff internally , all new arp bolts , nice double roller chain , crane adjustables and new .040 pistons . there is no ridge whatsoever and the walls all seemed to get a nice cross hatch with minimal hone . the only reason my friend gave the motor up was because he put a number correct motor in the 70 roadrunner he just finished , couldnt pass up the price "free" , so i really dont have much to lose if this doesnt do it . i have several more options on 440 blocks , but i sure would like to use this one . any help would be appriciated ! todd

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  2. how deep is the channel? Unless that block is steel and NOT cast iron, you wont be mig welding that. Cast Iron welding is a pretty specialized process when done correctly. Check around you area for a shop that can handle it, CORRECTLY! But,be prepared to spend some money as it aint a cheap process.
  3. BuiltFerComfort
    Joined: Jan 24, 2007
    Posts: 1,620


    Long ago I hung around a skinflint circle-track / demo derby racer. The track rules said $500 claimer motors, so everything was very low buck.

    Mr. Skinflint got a motor with this cross-cylinder blow-thru condition and ground out a V channel (with the deep part of the vee running up and down between the cylinders, not across them) and puddled in a bunch of weld build-up. It looked like a bad booger weld, no penetration to speak of, but that was okay.

    He explained that he was just trying to get a seal against compression that would not leak to the other cylinder, but not really trying to make the block strong, so the fact that the cast iron wasn't really welded much didn't bother him. The V shape kept his 'patch' from shifting left or right, and he just smoothed the gasket sealing surface and filed the area where his weld spilled over into the cylinders and called it a day. It worked the rest of the season, even with the nitro he snuck into the gas after tech.

    So, what are you planning on doing with the motor? Is it worth trying a low-tech trick like this, and how disappointed would you be if it failed? That's for you to answer.
  4. rschilp
    Joined: Sep 17, 2009
    Posts: 677


    Probably not the "right" way to do it, but how about just trying it with some nickel rod and a tig welder? the block is free, worst case it doesn't work but it shouldn't hurt the block anymore than it already is.

    If it doesn't work either get rid of the block or have a professional do it right, but that will require line-boring and honing at a minimum as the block will tend to move once it is heated to the right temp to weld the cast iron.
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  5. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,428


    I took a 283 chevy apart that someone had brazed in that area and it held but there might have been more meat between the cylinders.
  6. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,428


    How about deck the block and run 2 gaskets on that side.
  7. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,994

    Rusty O'Toole

    Brazing might be the best answer. It is not a wear or stress area and bronze is easy to work and to file.

    If you want to spend the bucks there is probably an auto machine shop that welds cracked blocks in your area.

    Either way should work.
  8. porknbeaner
    Joined: Sep 12, 2003
    Posts: 41,343


    We have a 440 that was pitted on the matting surface of the heads, we used a ball end mill to open the pits up and clean them then smeared JB weld in them and surfaced them. That was about 14 years ago now. JB Weld is not going to hold there because of where it is.

    Here is the problem that I see with welding that place, it is not of the filler will hold it is that you are going to have to bass a boring bar or at the very least a finish hone down the cylinders. If is not too deep I would have the engine decked and use thicker gaskets to make up the difference. But I would do both sides the same.
  9. 1971BB427
    Joined: Mar 6, 2010
    Posts: 5,517

    from Oregon

    Even the pros can have it go badly when it comes to welding. It needs to be heated prior to welding, then kept warm ass it gradually cools, or it can crack if it cools too fast!
    I had a 427 Chevy welded professionally in 1999 and the weld was a tiny 1/2" long crack. Even with all the right preecautions the block cracked in a different spot as it cooled and was a total loss. This was a well seasoned 1969 block, so it should have been fine.
    I'd not try to weld that block without the right rod, and the right procedures.
  10. RichFox
    Joined: Dec 3, 2006
    Posts: 9,820


    I have had my block welded also my head in the cumbustion chamber. Cost about $100 for the welding. You would never know it wasn't allways like that. Go for it. I guess it depends on who welds it. I can recomend a couple of guys 3000 miles from you.
  11. mopar, you need to establish how deep that damage is. I'll try and give you 2 methods the average guy can do at home. You should at least have a pair of dial or vernier calipers for this, they are cheap if you have to buy them and good to have.

    You can lay a good straight edge across the damage and use a small set of drill bits until you find one that is a nice fit with some drag between the crevace and the straight edge. Now measure the drill bit with the calipers to be sure of the size. Dont use the twist drill end of the bit, use the smoothe shank.

    The second way is put some duct tape on the same straight edge and then a little car wax on the outside of the tape, very lightly. Now also put a lite layer of the car wax in the crevace. Now mix up some JB Weld or your favorite epoxy and fill the crevace and place the straight edge with the waxy side down. Let it harden overnight. In the morning you should be able to take out the piece of epoxy and measure the crevace.

    Set up your crankshaft with the pistons for those cylinders and one ring only. Bring them each up to TDC and try and fiqure out or measure how far down the piston is in the cylinder if at all.

    You might just be able to deck the block or maybe even deck the pistons too, and make things better than new.

    Its hard to tell by the pictures alone, but the hone job looks horendous, not good for a Moly set of rings. Do you know what type of rings you have? Again, it could just be the picture, best of luck, Tr
  12. Joe H
    Joined: Feb 10, 2008
    Posts: 792

    Joe H

    Drill it right in the center and thread for a pipe plug. File flat and go, all you need is to block the compression from crossing over. It doesn't even need to fill the whole void, just dam the center up.

  13. If you end up decking the block, be SURE to chamfer the bolt holes when you are done. This will keep you from "pulling" the threads when you torque the heads done upon final assembly. This is often overlooked and a important step, TR
  14. I would just deck the block. Looks like .030 to .035 should be enough.
  15. 73RR
    Joined: Jan 29, 2007
    Posts: 6,242


    Given the location of the groove I'd first look at cutting the block to remove the trough. You get to decide how much of a cut is 'too much'.
    My second thought would be to 'touch' the groove with a ni-rod. A couple of small dabs, not much heat, just enough to stick. You could practice on another spot somewhere on the block to get a feel for the arc.

  16. DocsMachine
    Joined: Feb 8, 2005
    Posts: 279

    from Alaska

    There's a specialty rod made specifically for cast-iron welding, called "Muggyweld". It's not cheap- I paid something like $9 a rod including shipping- but I can say it welds very nicely. On clean cast, it butters about like 6011 on clean steel. I've used it to weld up two different cracked drill press castings now, with good to excellent results each time.

    What I don't know is how strong it is. The maker specifically says it's "softer" than the cast iron, so if things move around during heating and cooling, the weld will crack, not the original cast.

    It's the same idea as brazing- the brass is considerably softer than the iron, so will "give" as the iron moves, reducing the chances of cracking.

    The maker has lots of reports from guys that have used it to weld up cracked blocks- though typically only water jackets.

    I've always wondered how well it'd work for things like patching up the OP's block or repairing cracked heads, etc.

  17. 39 All Ford
    Joined: Sep 15, 2008
    Posts: 1,531

    39 All Ford
    from Benton AR

    I like that answer....

    edit... except now that I think about it, the plug would probably miss the fire ring in the head gasket....

    I think I might just try some JB Weld.... what the hell, the motor was free...

    I knew a guy that helped a mechanic who used JB Weld INSIDE a cylinder, (the cylinder had a vertical crack, and HAD to run the next morning for irrigation. The crack was lightly "V ed" filled, and honed. It ran for more than a year I know, and I don't think it ever did leak...

    I wouldn't glue a cylinder, but I would think about epoxying that groove....
    Last edited: Mar 11, 2012
  18. dana barlow
    Joined: May 30, 2006
    Posts: 3,614

    dana barlow
    from Miami Fla.

    high nickle rod made fo5r cast iron welds,works fine,used it myself on 2 engines,some place as stated.
  19. metalman
    Joined: Dec 30, 2006
    Posts: 3,273


  20. Coupe-in
    Joined: Feb 19, 2012
    Posts: 8

    from usa

    New here on the HAMB and might be able to help on this one. I've been a marine mechanic for many years and there is a product called marine tex the stuff is amazing! it's a two part syst that can be drilled and tapped I've used it on high pressure hoses , AC units, and cracked blocks. Not many people know about this product but I bet this will work!
  21. oj
    Joined: Jul 27, 2008
    Posts: 6,190


    If it were a valuable block i'd go for a pair of sleeves and epoxy the void - and i hate sleeves so it is a really tough call. I am an experienced welder and wouldn't even try to weld it if you brought it to me - not sayin it can't be done, cast iron is odd stuff and depends a lot on the tin content but the problem is that you gotta have enough heat to penetrate and that is also enough heat to turn the partition into a puddle of goo.
  22. Marty Strode
    Joined: Apr 28, 2011
    Posts: 4,195

    Marty Strode

    I have repaired blocks with the problem you have. I use a tig, on DC straight with some #12 copper house wire. You can control the heat and the buildup easily, without the spatter of a stick welder. The copper dresses down very nice.
  23. dave lewis
    Joined: Dec 12, 2006
    Posts: 1,346

    dave lewis

    I have welded several with mig welders, and more than a few with the tig.....
    Most were done on saturday morning, after friday night troubles( the learning curve for methanol was brutal, back before you could buy alky carbs over the counter !! )
    Funny this subject popped up today. I was showing one of my buddies a welded deck race block yesterday, We could NOT find the spot without a magnifying glass ! The weld was done back in 01.
    The factory brazes decks all the time...
  24. mashed
    Joined: Oct 15, 2011
    Posts: 1,474

    from 4077th

    Hubba Bubba. Grape.

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