Crankstuffers in a 372?

[idiotwithasaw]

My question is would this be possible/feasible? Would I have to machine too much of the case for clearance to make it work? And lastly would I see any real gains out if this mod. I have a set out of a 570 and they seem to fit fine on a 372 crankshaft, but the case isn't clearanced enough. Anyway, insight and advice welcome.

 

[Chainsaw Jim]

What's the measurement on the gap it leaves you? Or how much will need removed to fit?

 

[idiotwithasaw]

My main concern is how much material will I lose that the integrity of the case may be lost.

 

[Chainsaw Jim]

in order to answer your question you kinda have to know how much needs removed....hence my question of the measurement.

 

[blsnelling]

I must first ask the question, why? If I were doing anything, it would be to make the 576 run more like the 372.

 

[idiotwithasaw]

I haven't measured anything, I was asking peoples opinions, or seeing what experience someone has had if they have dine this mod.

What is the point of the crank stuffers anyway. A lot of the threads I read, especially on big bore upgrades, the subject of crankcase volume comes up. And it's always the same, more is better. But wouldn't having the stuffers in decrease the volume.

And Brad, what are the detractors of a 576 from a 372. I know the 372 is a legendary saw, and a favorite among builders, but does it really run that much better than a 576?

 

[Terry Syd]

Higher crankcase pressure raises the point of peak delivery ratio into the cylinder. In other words, it raises the powerband higher in the RPM range. Unfortunately, it also narrows the powerband.

So what do you want? Do you want a slightly stronger powerband at a higher RPM (good for racing, limbing) or do you want slightly less power, but over a broader range of RPM (good for day to day wood cutting)?

 

[Big_Wood]

I haven't measured anything, I was asking peoples opinions, or seeing what experience someone has had if they have dine this mod.

What is the point of the crank stuffers anyway. A lot of the threads I read, especially on big bore upgrades, the subject of crankcase volume comes up. And it's always the same, more is better. But wouldn't having the stuffers in decrease the volume.

And Brad, what are the detractors of a 576 from a 372. I know the 372 is a legendary saw, and a favorite among builders, but does it really run that much better than a 576?

keep in mind Ben, Brad is always talking ported. stock for stock......576 FTW it is heavier though and the OE 372 will lay a hurt'n on it ported. i like the XT's for longer bars though. they got that grunt to pull it. my ported OE i would say pulls the long bars just as well i suppose though but stock, the XT's take the cake.

 

[Chainsaw Jim]

No one has done it, but there is common knowledge of how it will not work?

 

[idiotwithasaw]

I'm more interested in the why it won't work. just saying it won't doesn't answer my question.

keep in mind Ben, Brad is always talking ported. stock for stock......576 FTW it is heavier though and the OE 372 will lay a hurt'n on it ported. i like the XT's for longer bars though. they got that grunt to pull it. my ported OE i would say pulls the long bars just as well i suppose though but stock, the XT's take the cake.

Does this mean that the stuffers, if you could shoe horn them into a case would benefit the xt more than the OE? also which 576 are you referring, the at or non at?

 

[Big_Wood]

I'm more interested in the why it won't work. just saying it won't doesn't answer my question.



Does this mean that the stuffers, if you could shoe horn them into a case would benefit the xt more than the OE? also which 576 are you referring, the at or non at?

i can't be sure what it would benefit more but alot of the XT saws have them and they run good. doesn't matter AT or not. the 576 is a ballsier saw in stock form

 

[locofrog]

And here it is a little over a year later and I'm still wondering if anybody has successfully done this. I tried the same thing and had the same results as o.p. I think 1mm or less on each side of the crank case should be more than enough for clearance. just a speculation though.

 

[cgraham1]

What is the point of the crank stuffers anyway. A lot of the threads I read, especially on big bore upgrades, the subject of crankcase volume comes up. And it's always the same, more is better. But wouldn't having the stuffers in decrease the volume.

@Chainsaw Jim, you have a 357xpwith a 272 top end? That's not much crankcase volume for a 70cc saw... how does that saw run?

 

[locofrog]

Well the saw in question at least for me will be a more race then work saw. the high rpm PowerBand created by the stuffed crank would actually help, but I'm just wondering if I should actually mill the crankcase out a little to make them work.

 

[blsnelling]

Make more volume so that you can re-fill it? Have you determined that you need less volume?

 

[locofrog]

No not really Brad I was just wanting to try it out lol. I picked up one of those wiseco pistons and hybrid bearings sets for the camouflage 372xp I was working on a whiiiile back. I'm finally getting back around to it. I had got some advice from you before on porting that 372. did you change up anything between using the wiseco popup and how you normally do one?

 

[blsnelling]

No not really Brad I was just wanting to try it out lol. I picked up one of those wiseco pistons and hybrid bearings sets for the camouflage 372xp I was working on a whiiiile back. I'm finally getting back around to it. I had got some advice from you before on porting that 372. did you change up anything between using the wiseco popup and how you normally do one?

No. I port them the same. I had a 1st generation piston and didn't see much compression improvement from it. I machined an additional pop-up on it.