Nik's Poulan Thread

[s sidewall]

We run the pump 38 hours every weekend, wish I knew more about fuel v electricity. It's single phase 220
On the foam cut a piece of 1/4 foam 1 x 1 and fold it in half and slide the rod through it at the end of the plate

May want to look at a diesel pump. That's what they use around my place on the sod fields and they are pumping a lot of water. They use the same setup at a tree farm near me. Just have to have a lot of water to run one. I think they are running 8" or 6" water lines.

Steve Sidwell

 

[Todd Loosli]

Well I have the 3800 running again and it runs fine was worth the effort. Tomorrow I'll cut some rounds with it. After 15 minutes it was still good.

 

[Jethro 2t sniffer]

Well I have the 3800 running again and it runs fine was worth the effort. Tomorrow I'll cut some rounds with it. After 15 minutes it was still good.

Hey Todd did you port it yourself?

 

[Todd Loosli]

Yes but all I did was square out the corners of the exhaust and make the intake as free flowing as I could. Didn't change anything else but I did make a thin base gasket and a 4000 muffler cut. It just seems to wake the 3800 up and now it's more zippy

 

[Todd Loosli]

Like this

 

[s sidewall]

Wonder if that would help a 3400 and a 3700.

Steve Sidwell

 

[Todd Loosli]

• 3700 is real close to the 3800 after porting and the 3400 would look like the 3800. I have a 3400 that is ported and it is much stronger. They run so much better when the exhaust and intake are opened up

 

[Todd Loosli]

You can see the difference between 3700 and a 3400 or 3800. Top cylinder is 3700 and 4000 shape. Bottom is a 3400 or 3800

 

[hotshot]

I'm going to make the adjustments and do another quick fit and then I'll cut out a bunch with the material I have. Should be easy now. I left my saw on the bench so I can check it easily.

Then make one sans the impulse hole (bottom left, marked “TEST” for proper P/V testing.

 

[EngineNoO9]

Then make one sans the impulse hole for proper P/V testing.

View attachment 755318

Just the one small hole right? Like the diaphragm on the bottom left of your photo? That's an easy mod I can do. I'd probably make fewer like that on an as needed basis.

I made the drawing changes. Need to cut out a new one this afternoon to check but should be set.

 

[Jethro 2t sniffer]

You can see the difference between 3700 and a 3400 or 3800. Top cylinder is 3700 and 4000 shape. Bottom is a 3400 or 3800View attachment 755287

Aww wow so it's not just the lack of chrome on the cylinder wall and the thick rings that make the 3800 run a little different. What did do on the intake side? When I had mine apart I thought about having a little dig around and maybe knife edge the divider. I just couldn't bring myself to do it though lol had the dremel in my hand but I did fix up the carb adapter though it had an abrupt corner in it and a bit of flash around. Also running no gasket

 

[Todd Loosli]

On the intake I only did the carb adapter, made it as free flowing as I could, didn't polish it just used the dremel like you did and a thin gasket.
I just was out cutting rounds with the 3800 and a 3700 both had same new chain and I couldn't tell the difference between them other than the higher compression on the 3700 when starting it

 

[Jethro 2t sniffer]

Ok nice have you measured squish between the 3? I wonder if the 3800 could have the base machined a tad to boost compression a touch. Or is it all down to the thin rings

 

[Todd Loosli]

I'll have to do some checking and get back to you, but that should be fun to find out.

 

[s sidewall]

If ya can post some pics on the intake mods, real close, that would be great. Don't want to mess up the ones I have by doing it wrong.

Steve Sidwell

 

[Jethro 2t sniffer]

Cool would be interesting. I never measured the 4000 as every thing I read said it would be fine with out a gasket

 

[Todd Loosli]

On the intake manifold just blend everything, I just did this one and it took me 15 minutes the picture looks ruffer than it is

 

[Todd Loosli]

On the cylinder the only difference is the base to full depth is .015 on 3800
The exhaust port is lower on the 3700 by. 020
That is all
The squish band is the same at 3.007

 

[Jethro 2t sniffer]

On the cylinder the only difference is the base to full depth is .015 on 3800
The exhaust port is lower on the 3700 by. 020
That is all
The squish band is the same at 3.007

Ok interesting I wonder if the lower port also adds to that compression boost

 

[Todd Loosli]

It would be the same as taking the base gasket out 2 times, not sure what one deleted would give so times that by 2