Stihl ms 460/660 Hybrid. 469e

[NateSaw]

Mark intake at BDC, make sure to mark the intake walls, not just the floor. Then pull the jug and piston, put the rings on the piston, insert and clock to your mark.

On this one, I wouldn’t widen all the way to the skirt. What does your V3 piston look like now?

It's the one on the right. Only thing I changed from this picture was I raised the full circle skirts, beneath the pin boss, and tapered out to skirt majors.

 

[Ketchup]

I would go in baby steps if you’re opening the lowers. Tree monkey 066’s flat out haul ass without touching the lower transfers. Breadcrumbs…

Different piston.

 

[NateSaw]

Different piston. Not sure if that matters.

Not by much. Heavier.

 

[Dolkitafreak]

@Dolkitafreak . Ethan you build spreed sheets and wicked race saws... What's your take on all this Tom-foolery?

Great thread, I love seeing the effort and modifications necessary for these types of builds. You’ve done a lot of work keeping everything clean and as proper as it can be! Takes serious time.

I’d be getting more air through that HD, numbers are fairly close to what I would start at. Seems to be running decent.

Typically if you’re willing to do this much work I’d look at adapter a crank with a longer stroke before cylinder swaps personally!

 

[huskihl]

Different piston.

I realize that. But

 

[Ketchup]

I realize that. But

Yeah. Baby steps.

If it weren’t for the uneven transfers I would leave the jug alone and focus on the carb.

Maybe it’s best to just fix the uppers and nothing else. Test again.

 

[Ketchup]

Not by much. Heavier.

I was thinking the full circle obstructs the lowers more than the stock piston. And 660 has a bigger case. 460 with that fat piston has less case volume, so stretching the lowers is less risky.

But now I think that’s too many things at once. Get the transfers square. Leave everything else alone. This is already a functional build. Too many tweaks at once could really set you back.

 

[NateSaw]

I was thinking the full circle obstructs the lowers more than the stock piston. And 660 has a bigger case. 460 with that fat piston has less case volume, so stretching the lowers is less risky.

But now I think that’s too many things at once. Get the transfers square. Leave everything else alone. This is already a functional build. Too many tweaks at once could really set you back.

Oh from here on, it's one at a time.

 

[Rich Fife]

660 has a bigger case. 460 with that fat piston has less case volume, so stretching the lowers is less risky.

I've been contemplating about big bore short stroke with small case volume creating excessive turbulence/flow characteristics (chaos)... my thoughts are it would hit hard from an idle but at WOT the charge isn't flowing smooth due to the excess. I'm wondering if a larger chamber or a slight transfer volume increase would yield slower but smoother flow characteristics...

But now I think that’s too many things at once. Get the transfers square. Leave everything else alone. This is already a functional build. Too many tweaks at once could really set you back.

Agreed. 1 small thing at a time with great baseline notes as well as detailed notes of changes and results of those changes.

 

[ManiacalMark]

Definitely needs work but not too bad, looks like it has way more blowdown than I’d like but I’ll find out when I time it.

 

[NateSaw]

Definitely needs work but not too bad, looks like it has way more blowdown than I’d like but I’ll find out when I time it.

That look as rough as mine. We probably bought them from the same place. It'll all come down to plating, in the bitter end

 

[ManiacalMark]

It’s a dukes brand

 

[NateSaw]

Definitely needs work but not too bad, looks like it has way more blowdown than I’d like but I’ll find out when I time it.

Same as mine. The transfers are tight enough... Leaves room to lift. Kinda.

 

[NateSaw]

It’s a dukes brand

It's a HEMI right?

 

[ManiacalMark]

Yeah

 

[Ketchup]

It's the one on the right. Only thing I changed from this picture was I raised the full circle skirts, beneath the pin boss, and tapered out to skirt majors. View attachment 412047

So V3 looks kinda like this?

 

[NateSaw]

So V3 looks kinda like this?

View attachment 412086

Ohhhhh yeah! I was going to make the lower full circle skirt thingys into air scraper fans like that! What is that?

 

[ManiacalMark]

Just under 99, 137-138 and 78.5 no gasket 0.030“ squish

 

[Ketchup]

Ohhhhh yeah! I was going to make the lower full circle skirt thingys into air scraper fans like that! What is that?

That’s just junk. I just did that to take a photo. Better than trying to describe it.

 

[ManiacalMark]

Also, not a ton of meat in the band to cut out of the 46 BB. I got just enough out to run a 660 piston with a base gasket.