How many broken cylinder fins are too many?

[RevsBaja]

I am working on building up a 1200 and have a brand new set of 83mm big bore pistons. The outdoor cats got into the garage and knocked the boxes off the shelf resulting in 3 out 4 cylinders with broken fins.

I've included pics of the two worse cylinders.

The engine will go into a baja bug so it will get plenty of air. Are these cylinders now too far gone to use?

Thanks for any input or advice.

[/b]

[glutamodo]

Me, I draw the line at one cracked or broken fin.

Those are big bore 40HP, so they have thinner walls than was stock -but not terribly so- and they have more fins overall than the original 1960s engines had in them, and larger fins (holes in them and not 'winged out'). But all of that is there because it is rather needed, and your example is more damaged that I would want to use.
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Andy T.


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[TDCTDI]

Weld them back on.

Is it a great solution? No, but are you willing to toss them & get another set?
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[6T5 square]

Get rid of the cats
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[bluebus86]

get new cylinders. the part broken is near the high heat source,, the combustion area. also.... kill the cat

if those are indeed big bore, old stock cylinders could I supposed be bored for the pistons you have. but as other guy noted, the fin design is different from stock to big bore, but even stock fins are better than missing fins.
the vendor might be able to supply cylinders only if you ask nicely.

Bug On! Fully Finned, like a Fish!
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[RWK]

Keep the cats, they kill the mice that get into engine and build nest in the shroud, end up with same problem but won't know about it until its too late, braze the fins on, work's better with cast iron.
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[Rome]

[Eric&Barb]

Do keep in mind that the cylinders are made of cast iron. So will not work with normal welding wire when the cast iron is at room temp.

https://duckduckgo.com/?q=welding+cast+iron&t=canonical&ia=web

On the other hand you could try tack weld those on cold in a few spots, and then heat up for brazing or hot welding.
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[wheel607]

Braze.

[splitjunkie]

Cast iron can be welded but I doubt the cylinders would still be within spec once it was finished. You would also have to weld the entire seam for them to be fully functional which would increase the heat used and the chances of the cylinders warping.
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Chris

You know, a lot of these scratches will buff right out... Jerry Seinfeld

[splitjunkie]

They are toast. Pull the pistons and put them in the classifieds and buy a new set. Even if you could get someone to weld them and not warp the cylinders you would cost at least as much if not more than just buying a new set.
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Chris

You know, a lot of these scratches will buff right out... Jerry Seinfeld

[motofly196]

If those were mine, I wouldn't junk them. Do you have access to an oxy/ acetylene torch? You cant MIG weld that. Cast is full of so many impurities, it will just pop and burn back. But you can braze the fins back on. There are plenty of you tube videos on how to do it. Silicone Bronze rod is what I'd use. Things in this world are not always junk because they are broken. What have you got to lose?

[TDCTDI]

Holy hell, it's not that difficult.

Here's a broken cylinder that I was playing with...

No, welding to cast iron is not ideal, but it's not like the fins are under any stress or are relied upon to keep something together. Here, I tacked the broken fin back on, no tools, clamps, or fixtures.

Then I ran a bead on it, flux core mind you.

And after cleaning it up with a grinder...

You could try to heat the cylinder first but they were kinda designed to dissipate heat quickly & they did so as the inside of the cylinder bore only got warm to the touch, hardly enough to worry about warpage.


You'll only have access to one side of the fin so start with the furthest one in & work your way out.

This took five minutes, it took longer to take pics, download them & peck the reply out.


Keep the cats, you might have to eat them soon.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[motofly196]

Perfect repair TDC. I honestly think if you put the broken fins down, you wouldn't notice a thing. There you go...flux if you've got access to MIG, and Braze if you've got a torch.

[splitjunkie]

This is what Lincoln recommends.

https://www.lincolnelectric.com/en-us/support/weld...t+provided
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Chris

You know, a lot of these scratches will buff right out... Jerry Seinfeld