Struggling 3-fo-six

[huskihl]

Seen 346 race saws with 170° of exhaust duration. Also seen many 346 work saws at 140° duration. You should be able to make something run in that range.

 

[Dolkitafreak]

Seen 346 race saws with 190° of exhaust duration. Also seen many 346 work saws at 140° duration. You should be able to make something run in that range.

I may give 98-118-78 a try? If thats a turd, 96-116/118-78 and stagger transfers? What says you-grand master sausage?

 

[huskihl]

I may give 98-118-78 a try? If thats a turd, 96-116/118-78 and stagger transfers? What says you-grand master sausage?

I’m not really certain of the transfer heights on race saws. Or anything in race saws really. I was more thinking it should run decent enough where it is and it might not be timing numbers, but shapes and sizes of the ports. Or something else even. Idk

 

[cus_deluxe]

bump, whats this thing doin now?

 

[Dolkitafreak]

bump, whats this thing doin now?

Currently it’s holding down a shelf real well. I’m actually gonna go a different route to be different and stuffs.

 

[Nutball]

Will epoxy hold in the upper transfers?

Yes

 

[drf256]

Interesting thread.

Are 346 P/C kits still in the $100 range?

I’m not so sure that epoxy will hold up in uppers. Yes in the tunnels and intake, but the uppers can get some back flow and I’m not sure it can handle the thermal exposure.

You have the chamber welded. Any pics? What is your elevation?

Seems odd that you’d need your chamber welded to get into the 200 psi range with a band cut of .075 (if I am reading correctly).

On a quad port I’d want more case compression and BD as well.

 

[Dolkitafreak]

Interesting thread.

Are 346 P/C kits still in the $100 range?

I’m not so sure that epoxy will hold up in uppers. Yes in the tunnels and intake, but the uppers can get some back flow and I’m not sure it can handle the thermal exposure.

You have the chamber welded. Any pics? What is your elevation?

Seems odd that you’d need your chamber welded to get into the 200 psi range with a band cut of .075 (if I am reading correctly).

On a quad port I’d want more case compression and BD as well.

I’m at 1100 feet, after the machine work it was 180ish, exhaust is high so that bleeds off a lot. Yes the cylinders are still cheap. The saw was a turd with the intake at 76 too, so I lowered it hoping for gains, still *s-word.

 

[drf256]

101 is high?

In the few saws I’ve done, raising the exhaust roof hasn’t bled off quite as much pressure as I thought it would. Seems like the small chang in swept volume didn’t equate to that much reduction in static compression. Again, only speaking from my limited experience.

I take around .060 from the band in an 026 and cut the dome off the piston. At 102 ex roof I’m at around 220-230. I’m at 230psi asl.

Something seems amiss here.

 

[Dolkitafreak]

101 is high?

In the few saws I’ve done, raising the exhaust roof hasn’t bled off quite as much pressure as I thought it would. Seems like the small chang in swept volume didn’t equate to that much reduction in static compression. Again, only speaking from my limited experience.

I take around .060 from the band in an 026 and cut the dome off the piston. At 102 ex roof I’m at around 220-230. I’m at 230psi asl.

Something seems amiss here.

It seems the general consensus here is that 101 is kinda high for a 346 yes-I know of some going much much higher with good results but clearly something isn't happy with me!

Any advice you have would be appreciated, as frankly I'm a little stumped. Pretty close to going off the deep and altering it a ton like one person suggested, whats the worst that happens, I ruin a turd?

 

[cus_deluxe]

id personally like to see a pic of the inside of the cylinder just outta curiousity. also, kinda silly, but did you check your ring end gap?

 

[Dolkitafreak]

id personally like to see a pic of the inside of the cylinder just outta curiousity. also, kinda silly, but did you check your ring end gap?

I'll get a pic. Piston and cylinder were both new, ran fine stock and had normal compression for a stock 346 so I never bothered.

 

[Nutball]

I've used JB Weld in the uppers of a ms250. I've run it pretty hard and hot without intentionally trying to overheat it, and so far it has held up. I'll check again in the next couple weeks after having put 10-20 tanks through it. I think too much cooling flow goes through there to overheat the 550degF rated epoxy. My main concern would be heat expansion cycles making it come loose. I also plan to fill and reshape the uppers in a FT660 cylinder and test run it.

 

[Dolkitafreak]

I guess the only pic I have currently is of the uppers! I can get some this weekend or the rest of it. This was before I tapered the lower transfer bridge between them. I think I *f-worded up the direction of them.

 

[srcarr52]

Those entrance angles look awfully steep.

 

[Dolkitafreak]

Those entrance angles look awfully steep.

Steep vertically? Hard to see in the pic but they’re flat as a board to the back corners, not sure if flat or aimed upwards is preferable.

 

[srcarr52]

Steep vertically? Hard to see in the pic but they’re flat as a board to the back corners, not sure if flat or aimed upwards is preferable.

It's pretty hard to tell from pictures, and the lighting in that one is bad. Bend a piece of wire to 90deg so you can lay it on the cylinder wall and have the short tip in the transfer port for reference.

 

[cus_deluxe]

and i wouldnt be surprised if that primary is short circuiting

 

[Bjorn]

Hello, this is how I did it.

 

[Nutball]

A view through the exhaust port may help us see the actual angle too