Welded popup. How to?

[exSW]

Well?

 

[hseII]

Well?

Don't.

 

[exSW]

Don't.

I'm not running out to the nearest guy with a buzzbox and a Community college certification.

 

[Deets066]

@drf256

 

[Lee H]

I know it has been done. But to what success I don't know. I read
somewhere that distortion was the main concern. I welded a skirt
on one of my saws and so far so good. When I was in my teens I
had a karting book. In there was an article about modding a west
bend kart motor. They were welding to an original pop up to gain
compression. If memory is correct I think they were welding with
piston in a dish of water so not to over heat the entire piston.

 

[Deets066]

Weight is what will hinder it

 

[Redfin]

Depending on the piston there may be enough material in other areas to remove to offset the added.

 

[wcorey]

Pretty easy really, just tig a bead around to build it up, then machine to spec.
I usually profile them into a sort of bell curve rather than the abrupt bevel and flat top.
Contamination/porosity is the one issue that, as with any welding, can sometimes be a pain.

I was playing around with a surplus of 350 pistons leftover from 353 flattop upgrades,
filling in the dish to make them flat. Added around 3 grams of weight.
One thing I ran into there was overheating and collapsing portions of the ring groove,
normally not an issue with welded popups because you're not that close to the edge.
Did popups on a couple cause why not since I'm welding/machining anyway.

Distortion of other parts of the piston didn't seem to be a problem.

One odd thing was that a couple of them made less compression than expected, I'm thinking the ring groove issue was somehow at play there even though the ring seemed to fit fine.

 

[hseII]

I'm not running out to the nearest guy with a buzzbox and a Community college certification.

I didn't assume such.

I only say that because, as you can see, sometimes there aren't any gains.

If something happens down the road, & the piston must be swapped, you'll have to do it again.