Tractor Saw

[blsnelling]

I've been keeping this build under wraps until I knew it'd at least run. I've never been so nervous in my life to fire up a fresh build. I tried a bunch of new things I'd never done before.

First of all, Jacob J gets a big THANK YOU for helping out as technical advisor for the build. He built a couple like this several years ago, and they're still in service today as milling saws.

This cylinder is the one I used for the Wiseco testing. The skirts being a little wider on that piston, the ports ended up too wide for a standard 066 piston. So I asked JJ if he knew of a piston that might work. The answer was a Husky 385XP piston. But it's not just a dropin replacement. The 385 piston is significantly taller.

I started with a .048" popup, taking the crown down to .090" thin...I mean thick, lol. Thanks to Nik for again doing a great job! I also "flattened" the side of the piston and put windows in it.

The rod IDs are the same, but the 385 wrist pin is larger. That means you have to use the wrist pin bearing and pin for the 385.

I then had to space up the cylinder. I ended up using 6 OEM gaskets and one made of .005" pop can aluminum. The total was about .110". I crushed each factory gasket individually in order to flatten out the raised portion. I didn't think it wise to try to do them all at once.

Even after spacing up the cylinder, I still could not run the bottom ring. I may go back in at a later time and relocate the ring locating pin inbetween the exhaust and transfer. So for now, it's only running one ring.

 

[blsnelling]

Here's the piston at BDC.

Since this cylinder had been ported previously, I chose to leave the intake port timing where it was. So I trimmed the bottom of the intake side piston skirt to get the intake port timing back where I wanted it.


I replaced the 6x25 cylinder base bolts with 6x30 bolts for an 084. This required clearancing the cooling fins to get the bolts in the base holes.

Now, that's not what had me so nervous. That was the porting experimenting I did. I completely removed the transfer bridges. Not only that, the ring end locations allowed me to greatly widen all of the ports. Both the intake and exhaust are a full 70% of bore measured along the chord, straight across. I also significantly widened the tranfers some more. Removing the transfer bridges made it much easier to get in there and flow those passages.

All of that made for an extremely nervous guy firing this thing up for the first time this afternoon!

JJ told me early on that this was not a RPM setup, but would have almost unstoppable torque. That's exactly what I got. I do plan to go back in and play with the port timing a little more, hoping to buy a few more RPMs.

In the vids here the saw is wearing an 8-pin rim and a 32" full-comp B&C. This is the first tank of fuel on a freshly honed cylinder with a new piston and ring.

This may not be the fastest GTG saw, but I've never had more fun building a saw. Nothing was text book, and each step had to be determined after completing the previous. There was nothing cut and dried about it. It was really a lot fun. Thanks again Jacob J!


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[Jacob J.]

That thing just sounds cool. One part about it is that you've added a lot of base volume so that helps draw out that long, broad torque band. The thing about the 385 as compared to the 066 is that the 385 has more of its stroke length in the case rather than the cylinder and that's where it gets its RPM range from. So essentially with this build you're moving a lot of volume out of the case.

For the long term though it may pay off to make a solid aluminum spacer rather than have all those base gaskets. I made the spacers on mine with carbon fiber since I didn't have the aluminum plate at the time.

 

[FATGUY]

Awesome work Brad. JJ, is there anything you don't know?!

 

[Arrowhead]

Yea..... I taught JJ everything I know. LOL (i wish). With that much torque it may even cut faster with a 9 pin. Good Job!!!

 

[blsnelling]

That thing just sounds cool. One part about it is that you've added a lot of base volume so that helps draw out that long, broad torque band. The thing about the 385 as compared to the 066 is that the 385 has more of its stroke length in the case rather than the cylinder and that's where it gets its RPM range from. So essentially with this build you're moving a lot of volume out of the case.

For the long term though it may pay off to make a solid aluminum spacer rather than have all those base gaskets. I made the spacers on mine with carbon fiber since I didn't have the aluminum plate at the time.

Good advice on the base spacer. I didn't want to invest the time in a real spacer if it was just going to grenade when I first fired it up, lol. Now that I'm over that bridge, I'll have to see what my machinist can do

I'm going to try a little more exhaust duration and maybe open the venturi on the carb to help get the RPMs up where I'd like to see them. I'd love to get them up another 1K, where I normally see a 066 at.

 

[Jacob J.]

Awesome work Brad. JJ, is there anything you don't know?!

I have no idea what women are thinking...

Good advice on the base spacer. I didn't want to invest the time in a real spacer if it was just going to grenade when I first fired it up, lol. Now that I'm over that bridge, I'll have to see what my machinist can do

Luckily you have a highly talented machinist nearby who I think can make that happen...

 

[outdoorlivin247]

What is the max RPM on it now?...

 

[blsnelling]

What is the max RPM on it now?...

About 13K, but I don't have it tuned that high yet. I'll lean it out a little more tomorrow. I normally see about 14K on an 066 I port.

 

[outdoorlivin247]

About 13K, but I don't have it tuned that high yet. I'll lean it out a little more tomorrow. I normally see about 14K on an 066 I port.

So you built a torque monster and still want to see 14,000+ RPM.....Did you put a tach on it in the cut?...It sounds great where it is at and should only get better w/ time...

Are you going to put it on a mill or are you still going to use your stock 084 for that?...

 

[FATGUY]

I have no idea what women are thinking...

probably best we don't

Luckily you have a highly talented machinist nearby who I think can make that happen...

thanks man!

 

[blsnelling]

So you built a torque monster and still want to see 14,000+ RPM.....Did you put a tach on it in the cut?...It sounds great where it is at and should only get better w/ time...

Are you going to put it on a mill or are you still going to use your stock 084 for that?...

Did you say stock You really think that 084 is still stock:greenchainsaw: Nah baby nah It's not near what my other one is, but I did port it. I left it conservative though since it will see milling duty.

Yes, I still want more RPMs. I think they're in there. I want my cake and eat it too!

 

[madhatte]

Good work, Brad, JJ, Nik. This stuff is why I'm on this board.

MORE!

 

[caotropheus]

Brad,

First time I see a 066 with that sort of adaptation for air intake. Can you please give more details on the air intake?

 

[Hddnis]

Now why would you want to cut tractors with a chainsaw?:biggrinbounce2:


That looks like it would be tons of fun to run. Nice work, as usual.



Mr. HE

 

[brncreeper]

Quality job on the circular interpolation crown, but no tractors?

 

[mdavlee]

Neat build. I have wondered if the 385 piston would work in a 660 since a 288 piston would. Now I know what that it will with a lot of machine work.

 

[7sleeper]

Great to see that you three(Brad, Nik & Jacob) aren't bored at the moment! I was already a little bit worried because Brad's last rebuild is already a little longer back!

Time to spread some rep again!

7

Edit: Can someone rep Brad & Nik for me. Jacob worked but for the others as usual "spread..."

Thanks

7

 

[BobL]

Way cool - but where's the tractor bit come into it?

 

[blsnelling]

Way cool - but where's the tractor bit come into it?

Torque like a tractor