Knucklehead repair

[MMasa]

That's the method Don used and his weld was the strongest part of the head.
Mark

[knuckleheadmike]

Steve,
A friend of mine welded an exhaust crack on my 41 knuckle,
We preheated in a oven for about an hour.
We used a bucket of sand to retain heat an allow positioning
Then, the part I don't understand; he used a TIG torch and stainless filler rod. Maybe because of the nickel content?
Then covered the head with sand and allowed to cool.
Wish I had more information. I've lost contact with him. Probably living out of his car somewhere in Northern California.IMG_1062 copy.jpgIMG_1056 copy.jpgIMG_1044 copy.jpgIMG_1043 copy.jpgIMG_1041 copy.jpg

[Steve Little]

Hi Mike. Thanks for the pictures and information. One of these heads is missing 3 fins and I plan to use the TIG and a cast iron filler rod to weld them on. Now that I’ve gained some experience with these Cast Craft rods I think they lack the fineness needed to weld something as thin as a fin.

[T. Cotten]

Hi Mike. Thanks for the pictures and information. One of these heads is missing 3 fins and I plan to use the TIG and a cast iron filler rod to weld them on. Now that I’ve gained some experience with these Cast Craft rods I think they lack the fineness needed to weld something as thin as a fin.

Steve!

Welding on a fin is futile, as it will always show.
Nor can you peen between fins.
Build up the missing fin bead by bead, carve it to shape with "whizzer wheels", then "distress and re-texture".

The last step is most difficult with silicon bronze or nickel, but piston rings 'distress' nicely, so if your rods machined easily at all, they should as well.

....Cotten

PS: Attachments show an aluminum fin that was completely missing, and 'distressing' tools (to be followed with steel shot blast).

[Steve Little]

Thanks Cotten. I replaced the centre mount on one of the heads by pad welding. It was a slow process and took about an hour of solid welding, chipping and wire brushing. It was broken off flush at the head and can be seen in the 3rd picture in post 15. I still plan to have a play with the TIG. I will post pictures when I do the job.

[T. Cotten]

For Folks who still insist upon a 'splice',..

Here's your raw fin stock: 5" X 3" X ~.100" sawn cast iron plates.

Email me at liberty@npoint.net with your address, and you can have one for the postage.

and Good Luck!

....Cotten

[Steve Little]

Thanks Cotton. I'm sure you will get requests for that material as they would help someone fix a head.

I used up the small pack of electrodes that I had, so ordered a new pack and got this head a bit further along.
Bolted it to the mill and machined off the high's of the pre-welded areas so that the rocker box could be installed, and used as an assembly jig.
For a bit of fun, I fit a 3/8” end mill and cut the sides of the middle mount. I’ll burr grind the end to assimilate the original shape at a later stage.

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Used a cardboard template to get the shape of the missing part of the rocker box support.
Then cut and ground Carl's replacement part to shape. When that was done I bolted the rocker box shafts to the tower supports and the new piece under the rocker box and tacked each end.

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[Steve Little]

I pre heated the head before tacking the mount in place but a couple of stress fractures still opened up after the tacks and bottom welds were laid. One crack is seen in the previous picture, on the outside fin, beside the tack. The other is between the area to be welded and the vertical fin with the scriber pointing to it. The cracks may be the result of the tacks, or may have been hidden fractures from the original trauma on the head.

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[exeric]

I know next to nothing about metallurgy, or welding but can stress relieving minimize stress cracks like that? By stress relieving, I mean shot peening, heat cycling, or vibratory shaking prior to welding; or is stress relieving suppose to be done after welding? Just wondering for the sake of conversation. I really appreciate you sharing your process, Steve.

[T. Cotten]

That's why I am not a pro welder, Steve!

It would seem that your filler material shrank more than the casting would allow.

....Cotten

[Steve Little]

Hi Eric and Cotton. Thanks for livening up the thread and contributing ideas and comments.
Aside from pre and post heating the head, I have a chipping hammer and a sharpened file that I used for chipping the slag off and tink, tink, tinking the weld after each pass.
Placing the head in lime for a slower cool down might have been the ticket for success. Learning and sharing the quirkiness of cast iron and gaining some experience along the way, is what it’s about.

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I used the angle grinder to grind down from the top of the joined area until I reached the weld that I had laid underneath the bracket. I also ground a nice V into the crack which was near the vertical fin and then pre-heated the head and welded both areas. Then back in the oven for an hour and then tried a new method…suggested earlier on....lowered the oven by 20 degree increments every hour and then left it in the oven over night. I left it at a temperature that was just bearable to the touch….for an old boilermaker/welders hand that is.

Clamped the head into the mill and took the welds down to the original metal. Then drilled and tapped the middle bracket.

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Getting closer and closer to usable heads.

[T. Cotten]

Ever remove a bearing race by welding a bead around it, Steve?

Kyle Oanes and I discussed this once, and my contention was that the tool steel shrank when it reached a critical temperature, and Kyle contended that the bead shrank and pulled the race smaller.

We were both half-right.
I think your filler rod has a high shrink rate, and if you have "slag", its a bother as well.

Please look at the pic I posted earlier, where the bead has been ground away to show complete penetration, and virtually no visible difference with the casting.
There was no flux used, so there was no slag. Primitive.

....Cotten

[Steve Little]

The CIG 5mm cast filler rods have arrived and I have switched over to using these with the TIG.
Using the TIG and these filler rods is more manageable while building up these missing fin sections.

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4 hrs of solid welding, equals 2 roughed in fins done by pad welding technique.
The head is in the oven going through the post heat stages. I can’t continue on to welding the next fin yet, as I have to shape the vertical fin to give me room to get in beside it to build up the next one.

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I’m glad its Friday. All the stress of welding cast iron is giving me the fits….I might have misspelled that last word.

[Jon Louis]

My only trick to 'cast head welding'...Is a custom made, gas fired oven..heats the head to near red.. quick out to weld ( unit has been tacked ahead ) .. then back in the oven for as many hrs as I have patience for..slow cool over 24 hrs..been workin good to great... so far..JL

[Steve Little]

Thanks for the input Jon.
What type of filler rod or electrode do you use. Do you braze, TIG, or electric weld the heads?

Regards Steve