POP-UP PISTON

[dastevoe]

Well here I go !
I think my next project is going to get a "POP-UP" (piston that is ).
Could someone OR everyone post their procedure on doing a WOODS MODDED saw with a pop-up ?
AND explain why you are doing each step and the potential gains with each operation.
This 038 mag P&C is begging for it ,and according to the little I've found, it should see some good gains.
Al Smiths' posts on his 038 mag indicates this is "A GOOD THING".
Also can this or has this been done on the 026 by anyone ?
I'll probably fire off the same question over at RS as well to tap into that pool of knowledge too.
Looking forward to what this leads to!
Steve

 

[SkwerI]

I guess your first step would be to find a pop up piston that fits the 038 magnum. Good luck!

 

[Al Smith]

Again simply pulling one out of my arse that works ,a pop up can be good .Is it better than a flat top or hemi domed piston ,good question .

A pop up does several things .By its' design it more evenly spreads the flame front .It provides better sweeping of the residual exhaust gasses on the transfer cycles .If done exactly correct it adjusts for the port realignment after removing base material to increase compression .

Much to many people who try and say somebody "stole" their idea ,this has been around for decades .Fact is I got the idea from a Ford piston so I had nothing to do with this practice .I doubt seriously if Ford sues me though .

How much to raise,how wide,what angle ,sorry I have no idea what is the best .What I can say is mine worked and worked well .

It's not that hard to cut one if you are familar with machining methods . Fact is a few folks have done pop ups using a milling machine instead of a lathe .

 

[Cut4fun]

Several people can make the pop ups for you and you know where.
I have had pop ups in several saws and still got a few of them.

You just dont buy a pop up, Rocky Skwerl you make it.

 

[squisher]

So do you just cut down the stock piston and then shave the cylinder to gain compression back?

 

[Al Smith]

Yep Squish ,that's pretty much it .

I've had these pics on a zillion times ,one more won't hurt .

The pop up which is on the Rocky special and the hemi domed stocker on an 038 Av . I just did portwork on the AV but will go back in and shave the jug when I get the chance . I won't carve the piston on the av .I was under the gun to get these two done .Done within the same week actually .

 

[squisher]

Cool, that looks like something I won't be trying anytime soon.

 

[Al Smith]

Well you gotta have the machines to do it with and the know how .It doesn't come over night although to me machining is not a big deal .

My old man said I came out of the womb with a set of micrometers in one hand and a wrench in the other .My mother disagrees

 

[NeTree]

That musta hurt.

 

[darkstar]

Al ,you have the cleanest work area i ever saw.

 

[Al Smith]

That's me ,Mr. Tidy alright .

 

[woodworkingboy]

Machine the squish area at the top of the piston crown. Leave 0.100" above the top ring groove for strength. How much material you want to remove depends on what squish clearance it will give you.