Nik's Poulan Thread

[Acornhill]

I would think flow from beginning to end would produce the most improvement, I am a novice when it comes to performance work on a saw but air flow, carburetor flow to manifold opening to squish to exhaust exit openings, throttle linkage etc also to tighten everything up. Then a top notch Sprocket, bar & chain to finish it off

I would say a reed valve saw would be slightly different as well


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[redunshee]

I would think flow from beginning to end would produce the most improvement, I am a novice when it comes to performance work on a saw but air flow, carburetor flow to manifold opening to squish to exhaust exit openings, throttle linkage etc also to tighten everything up. Then a top notch Sprocket, bar & chain to finish it off

I would say a reed valve saw would be slightly different as well


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I have done a little work on the intake manifold. Simply smoothed out the interior by removing the small ridge. Seems if you can improve flow it should improve perf. Haven't tried advancing the timing but know some guys have.

 

[James Miller]

I picked up the 3400 to get running for a coworker that wanted to get into heating with wood after running out of gas and coming home to a house that was 42*. He changed his mind so I'm Gona experiment with it once its oiling right. Was thinking BG delete, mm, and maybe an adaptor to run a more modern filter setup. Iv never done more then a muff mod on a saw so figured for what I have in it I could play with it a little.

 

[3000 FPS]

They are easy saws to work on so it does make a good candidate to try some new things.
While your at it match the exhaust port on the cylinder to the muffler. Like Acornhill mentioned we want smooth flow.

 

[redunshee]

They are easy saws to work on so it does make a good candidate to try some new things.
While your at it match the exhaust port on the cylinder to the muffler. Like Acornhill mentioned we want smooth flow.

One of my 3400's(not sure which one any more) I widened the exhaust port. Seemed to help a lot. If you compare the exhaust port on a 3700 to a 3400 you can see quite a difference between the two. The 3400 seemed quite choked up compared to the 3700. Not sure why the difference in design.

 

[3000 FPS]

One of my 3400's(not sure which one any more) I widened the exhaust port. Seemed to help a lot. If you compare the exhaust port on a 3700 to a 3400 you can see quite a difference between the two. The 3400 seemed quite choked up compared to the 3700. Not sure why the difference in design.

That is something I never noticed before. I will have to check it out. Thanks Bob.

 

[RedneckChainsawRepair]

I never measured to check either. Always just sent them to the folks that wanted them after making sure ok.

 

[3000 FPS]

It looks like the 3700 exhaust port is bigger on the 3700 or your bottom picture but it is hard to tell.
I would still like to measure them.

 

[Acornhill]

It looks like the 3700 exhaust port is bigger on the 3700 or your bottom picture but it is hard to tell.
I would still like to measure them.

I have both NOS cylinders and will check


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[s sidewall]

Looks like the opening is more square in the corners on the 3700 and rounded on the 3400.

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[redunshee]

Looks like the opening is more square in the corners on the 3700 and rounded on the 3400.

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That's how I see it. Room to widen the 3400.

 

[RedneckChainsawRepair]

Need to do a port map of them both and compare

 

[s sidewall]

Intake port on them the same or is the 3700 bigger also?

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[redunshee]

Intake port on them the same or is the 3700 bigger also?

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Not sure but if the intake manifold fits either saw, I'd say they are the same.

 

[James Miller]

https://www.smallenginechainsawpart...ulk-8133-530008133-530-008133-sold-per-ft-../
I use 3/16 X 3/32 Tygon. Not as flexible as the OEM line but it seems to work fine.

Does this look correct sir. Its an echo line but matches the size you suggested.

 

[fossil]

View attachment 606119Does this look correct sir. Its an echo line but matches the size you suggested.

I would assume since it's Echo line it's OK for oil. If it fits the pump and filter screen barbs you should be OK. After a few months you may want to check to make sure it hasn't gone hard.

Sometimes routing the line to the front of the tank can be a pain in the butt so look in the oil tank fill hole to make sure you can see the screen and line in the front of the oil tank before you bolt the pump down.

 

[s sidewall]

Not sure but if the intake manifold fits either saw, I'd say they are the same.

But the muffler fits both too, just wonder if port is bigger.

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[fossil]

But the muffler fits both too, just wonder if port is bigger.

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I've never measured the intake but I feel confident they are all the same in the 3400 - 4000. The carbs are all HDB 8-1 and the carb adaptors are all the same. The exhaust ports on the 3700 and the 3800 appear to be the same and both are larger than the 3400.
I suspect the 3700 - 4000 ports were made larger to make an appreciable + difference in the larger saws.

I'm guessing the 3700 and 3800 cylinders were shot in the same mold (different alloy) and the plating in the 3700 dropped that bore from 1.88" (unplated 3800) to 1.875"

 

[s sidewall]

@fossil,Finally got around to popping the seals out of the 5200 but didn't have time to mic the pocket depth, will do it tomorrow.

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[fossil]

@fossil,Finally got around to popping the seals out of the 5200 but didn't have time to mic the pocket depth, will do it tomorrow.

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Thanks Steve.