Throwing the works at a 372BB.

[jropo]

Pretty cool stuff! I never seen anyone weld on a jug before.
Bummer about the chrome, I'm glad you stuck with it.:msp_thumbup:

 

[srcarr52]

Yes I saw the weld on the ex port, weird, I've gone higher on the ex then that on a 372 and haven't had any trouble, this last one I cut the squish allot more then .030.

It's not the exhaust I have a problem with. The transfer are my main concern since I really want to get the flat entrance and a smooth turn in the port. I've ground out the top of a stock jug without cutting the squish before. After building this NWP BB I think it would could come close to squeezing it in the stock casting but I'm afraid with the AM jug there is probably a lot of casting shift and you couldn't do it consistently.

The top of the exhaust port is welded on just for a sealing surface. I never ground outside the existing casting but I'm sure I'm really close.

 

[parrisw]

It's not the exhaust I have a problem with. The transfer are my main concern since I really want to get the flat entrance and a smooth turn in the port. I've ground out the top of a stock jug without cutting the squish before. After building this NWP BB I think it would could come close to squeezing it in the stock casting but I'm afraid with the AM jug there is probably a lot of casting shift and you couldn't do it consistently.

The top of the exhaust port is welded on just for a sealing surface. I never ground outside the existing casting but I'm sure I'm really close.

Ok, I see what you mean. I think your ex port shape your going for is more of a megaphone so to speak, I don't normally do that on 372's.

 

[cowroy]

opcorn:

 

[srcarr52]

Maybe this will help with the exhaust shape question. The angle of the picture can be really deceiving.

 

[srcarr52]

And finally here is a video comparing the new 372 BB to my TN build off saw that has had a few updates since then and it has been broke in as I sent it to the build off with only 1/2 tank through it.

[video=youtube;Mnq_BAbOfNw]https://www.youtube.com/watch?v=Mnq_BAbOfNw[/video]

 

[parrisw]

Nice they both run pretty awesome.

Any particulars on the first one?

 

[srcarr52]

Nice they both run pretty awesome.

Any particulars on the first one?

Yes. http://www.arboristsite.com/chainsaw/174891.htm

The only real update to the saw since then is a worked over stock carb and a little over a year of being my go to.

 

[wigglesworth]

Maybe this will help with the exhaust shape question. The angle of the picture can be really deceiving.

Yep. Looks good.

 

[wigglesworth]

And finally here is a video comparing the new 372 BB to my TN build off saw that has had a few updates since then and it has been broke in as I sent it to the build off with only 1/2 tank through it.

[video=youtube;Mnq_BAbOfNw]https://www.youtube.com/watch?v=Mnq_BAbOfNw[/video]

Dang, that BB's got a set of nuts!!

That's a strong running saw.

Awesome work!

 

[benjy]

great thread! so did you machine the base in the end? interesting if u didnt. ben

 

[srcarr52]

great thread! so did you machine the base in the end? interesting if u didnt. ben

Yes I did but I had to finish the cylinder before I could get the piston in the jug to check the squish.

 

[benjy]

Yes I did but I had to finish the cylinder before I could get the piston in the jug to check the squish.

Ahhh ok. how much did you take off? whats the squish now? and did you use a lathe? sorry for all the questions i'm just in the process of doing my first build myself on a 362 body, 372 P&C. ben

 

[srcarr52]

Ahhh ok. how much did you take off? whats the squish now? and did you use a lathe? sorry for all the questions i'm just in the process of doing my first build myself on a 362 body, 372 P&C. ben

I took 0.030" out of the squish band so I ended up taking around 0.035" off the base to get the squish to 0.020". Yes I used a lathe and I've shown the process in other threads. I'd dig them up for you now but I got to be getting to work.

 

[srcarr52]

Ahhh ok. how much did you take off? whats the squish now? and did you use a lathe? sorry for all the questions i'm just in the process of doing my first build myself on a 362 body, 372 P&C. ben

Here is a build thread with pictures of cutting the base of the cylinder on the lathe. It's the build thread for the first saw in the video shown in this thread.
http://www.arboristsite.com/chainsaw/174891.htm

 

[srcarr52]

Page 2? Bump!

 

[parrisw]

I see what you mean by flat transfer exit. I just started working on a BB395 and the trans roof is much flatter then a 372. Now ya got me curious about doing the same thing to a 372.

 

[komatsuvarna]

If ya look real close, the uppers arent the same on an OEM 372 cylinder. Look in the back of the uppers where they transition from vertical to horizontal. One port kinda points up just a hair, and the other port points more across the top of the piston.

Now I can't remember which one points which way now though .

 

[parrisw]

If ya look real close, the uppers arent the same on an OEM 372 cylinder. Look in the back of the uppers where they transition from vertical to horizontal. One port kinda points up just a hair, and the other port points more across the top of the piston.

Now I can't remember which one points which way now though .

Yes they arn't too bad stock but when you raise the hell out of them, you get a much sharper angle.

 

[srcarr52]

I see what you mean by flat transfer exit. I just started working on a BB395 and the trans roof is much flatter then a 372. Now ya got me curious about doing the same thing to a 372.

I'm interested in seeing the 395BB. I might do one of those soon.