broken fin #5 head

[oldbusboy]

I was stripping my frame down today and the frame tipped over against the motor. I ended up breaking off a corner of a fin on my rear head.

My OCD won't allow that to be left alone, so should I just buy a decent looking used replacement? I assume it isn't cheaper to have somebody weld it up? It isn't an outside fin, so even if I could find somebody it would take some work.

Thanks for your responses.
Trevor

head.jpg

[scooterscum61]

Looks like a difficult one . I have welded fins before, when there inside like that it seem impossible at the least difficult to achieve a solid weld . if you just tack it on it will not have the cooling efficiency it was intended for . I have built the weld up solid and then reshape and retexture. It takes time but can be done . Hope this helps , I am not an expert, just sharing my experiences .

[gitguy]

Was there any colorful language that accompanied that event? I hate it when that happens!

Good luck

[exeric]

I know a guy that has a 54FL and he broke a fin on the head, on the left (show) side. He literally glued it back on with JB weld and said it was at least a 10 year old repair. I saw it, and it was a near invisible repair, but you could see it when it was pointed out. These are his claims and I've never tried it, so I'm just saying what some guy did.

[oldbusboy]

Thanks guys. I ended up buying a used head without any missing fins. Agree it would be a very tough welding job, so for now we'll swap it out. Trevor

[FNG1]

Just curious. Do you think the aluminum solder rods would work?

[chuckthebeatertruck]

Indeed, JB Weld works pretty good. You'd be surprised at how well. Yes, it does cut down on the transmission of heat -- but you won't melt down as a result. You pretty much only need to worry about the heat radiation if you have multiple missing fins or your motor runs exceptionally hot.

On inside fins; I've always gas welded/brazed them. I've never been able to get a MIG head down there and don't have TIG. A small tip allows you to get right in there and feed the rod with little in the way. The harder part is keeping the fin still :-)

But I cannot gas weld alloy for crap and so I've only alloy brazed on alloy fins.

This is indeed more like "solder" than brazing as the flow out temperature is around 750-800 degrees. It works best on sand cast parts that have big open pores for the capillary action of the solder/braze. Plenty good for heads; but also getting near the point where the base alloy turns plastic so you have to be careful to not over or underheat if you want a solid connection.

I've primarily used Hobart rods; but the last package was HTS2000. The big challenge there is that once you reconnect the bits with a zinc based rod like the alloy rods . . .it's pretty contaminated and electric welding is very challenging.

Otherwise, it's a pretty simple affair to solder/braze them back on. Hiding the repair fully is another matter. Unless you overweld/braze and grind back, the tell tale line often shows up when dirt gets all over the place.

[larry]

Saw off the outside fin to gain access to the broken one. Then weld repair one at a time.

[T. Cotten]

Just curious. Do you think the aluminum solder rods would work?

You mean like "MuggyWeld", Larry?

I bought some for my TIGmeister a few years back, and he wasn't impressed.

But a couple of weeks ago, I filled a damaged spigot hole in a potmetal venturi!

The tensile strength was great, and the aluminum rod has to be even better; Sometimes a little ignorance is a blessing.

....Cotten

[FNG1]

Hi T. Cotten, I don't know specific brand names. I have a bundle of around 15 left over from a flea market purchase a long time ago. It really acts like solder not weld. I think they are zinc like Chuck said. I have only used them for non structural repairs, and have mixed results using it. I think Larry meant real deal welding.

[T. Cotten]

I've got Muggy aluminum rods, too, FNG1!

But I've never tried them, as I used to have a trusted local TIGmeister or two. (They either died or escaped my state.)

Traditionally, we had the best result building up entire fins bead-by-bead, art-carving them, and re-texturing with steel shot before fine glass beads, for a 'perfect' repair.

But that was then. Good luck Everyone!

....Cotten