Nik's Poulan Thread

[RedneckChainsawRepair]

I guess I should have stated that but I thought, assume, everyone knew that, also the space between the transfer ports is wider on the 3800. I was trying to figure out why the compression was greater in the 3700. Was just saying that the dimensions from the base to ports and ports to top were the same , also the combustion chamber was same. Thanks for saying that the bore was bigger on the 3800, don't want anyone to screw up a p,c cuz they thought it was the same

Thread awhile back with the psi info etc. https://chainsawrepair.createaforum.com/poulan/poulan-3800-5231/

My 3800 was hair under 140psi

 

[RedneckChainsawRepair]

Some more numbers pulled from old threads

Quote from: Cut4fun . on August 20, 2016, 09:15:14 am
Quote from: Cut4fun on April 14, 2015, 01:08:16 pm
Quote from: Cut4fun_ on November 30, 2014, 10:45:20 pm
Some info I have saved in the poulan 4000 thread.

4000 bore 49.2mm

3700 47.7mm

3400 46mm

Quote from: 3000 FPS on February 04, 2015, 01:27:28 pm
The 3400 run around 125 to 135 psi.
The 3700 will run around 150 to 160 psi
The 4000 is the same as the 3700 they both have two thin rings and the only real difference is in
the bore size as far as compression goes.

I have seen the exception posted where someone got up to 175 psi on the 3700 and 4000 models.

Any other info just add to it. Thanks

New owner put his gauge on the 3.0 3.4 and 375 to check psi. I never did as they felt normal ranges to me.

3.0 3.4 135psi

375 150psi

 

[Todd Loosli]

Much thanks J J

 

[hotshot]

I guess I should have stated that but I thought, assume, everyone knew that, also the space between the transfer ports is wider on the 3800. I was trying to figure out why the compression was greater in the 3700. Was just saying that the dimensions from the base to ports and ports to top were the same , also the combustion chamber was same. Thanks for saying that the bore was bigger on the 3800, don't want anyone to screw up a p,c cuz they thought it was the same

Good question & info, the thin rings must seal better against chrome, versus the fat rings against an aluminum bore. Thin rings are tempered steel & the fat rings are cast iron...

If the piston deck heights, cc volume, both pistons being flat tops, and exh ports are the same height, then the pressure should be close. I’ve never measured the parts side by side, like you did there.

My x3 3800 average 140# & the 3700 are all right over 150#, big difference there.

I know if you keep the cc the same volume & increase the bore size, the static pressure rises, so that 3700, being a smidge smaller bore, is counterintuitive!

Maybe the chrome plating up in the cylinder top edge of the 3700s provide a smaller squish too.

Either way, both those saws have cut a ton of wood stove fodder year after year.

 

[s sidewall]

I do like my 3700, only weak point is the oiling system, been nice to have been gear driven but that my opinion.

Steve

 

[fossil]

I do believe the 3700 cylinder and the 3800 cylinders come out of the same die cast mold. The plated bore on the 3700 is 1.875" and the the bore on the bare 3800 cylinder is 1.880". The aluminum alloy would very likely be different as the bare bore requires the use of a high silicon aluminum alloy. I think the Chevy Vega was the first north American car to use this technology.

Poulan 3400, -4000 saw stroke is 1.319"(33.5mm) and displacement


Volume of a cylinder V=πr2h

3400 3.14159 X (1.81/2 )squared X 1.319 = 55.614 cc

(16.3871 cc per cu in)
3400 bore is 1.810"

3700 59.681 cc Bore 1.875"

3800 59.9999 cc Bore 1.880"

4000 63.562cc Bore 1.935"

 

[fossil]

I do believe the 3700 cylinder and the 3800 cylinders come out of the same die cast mold. The plated bore on the 3700 is 1.875" and the the bore on the bare 3800 cylinder is 1.880". The aluminum alloy would very likely be different as the bare bore requires the use of a high silicon aluminum alloy. I think the Chevy Vega was the first north American car to use this technology.

Poulan 3400, -4000 saw stroke is 1.319"(33.5mm) and displacement


Volume of a cylinder V=πr2h

3400 3.14159 X (1.81/2 )squared X 1.319 = 55.614 cc

(16.3871 cc per cu in)
3400 bore is 1.810"

3700 59.681 cc Bore 1.875"

3800 59.9999 cc Bore 1.880"

4000 63.562cc Bore 1.935"

Wow. I guess I should have read ahead. All the info needed far above my post.

 

[Todd Loosli]

3700 on the left and 3800 right, paper lines the same

 

[Todd Loosli]

Wow after a closer look the exhaust port is very different, the red is the 3700 and the other 3800

 

[Todd Loosli]

Looks like the 3400 has the same as the 3800

 

[Acornhill]

Finally able to get outside to split some wood

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[RedneckChainsawRepair]

Sometimes I just got to shake my head and laugh at my older self.
Setting up poulan 380 60cc with 24" 84dl 3/8 today. Well I grabbed a stock 330 54cc by mistake and started test cutting with the 24" full skip square filed chain in the cuts. Buried in dry ash log.
Well I thought man this ported 60cc is maxed out. Then I looked at cylinder and went DOH! I was doing this with a stock 54cc 330.
The 380 has a 330 recoil cover on it still too. But missing some bars.
Put 24" on 60cc and that was more like what I was expecting. No troubles with bar buried in cuts.

 

[Todd Loosli]

I travel that road quite often In a day

 

[s sidewall]

Finally able to get outside to split some wood

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That's the only way for me to think about splitting wood.

Steve

 

[Acornhill]

More finished

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[s sidewall]

Looks like the same pile but at a different angle. [emoji23]

Steve

 

[Todd Loosli]

I always enjoyed splitting wood with my home built splitter, thinking that I made this and it works, then after 10 logs it's a job that has to be done and I can't find anybody else to do it lol

 

[3000 FPS]

I have dropped the cylinders on two different 3800's with a squish at around .022" and the best compression was 150 PSI.

The same thing on a 3700 cylinder and I got 175 PSI. The thin rings and chrome cylinder make the difference.

 

[s sidewall]

Bet that 3700 had the power with that much compression.

Steve

 

[redunshee]

Well got back to fixing my 2300 and 3800. The 3800 was leaking air at the pump cover. Had another cover and gasket that I installed and it now doesn’t leak and hold pressure. I also put a new check valve in the 2300, replaced oil line and it now oils. It does leak oil after shut off so I presume loosening oil cap will reduce the pressure. While in Vermont I also got my 3700 going with a carb rebuild and new recoil rope. Now all I have left is a 3400 and 4000 to get going.