Author Topic: Poulan 3450 3750 and PoulanPro 330 380 Tank Vent Retrofit  (Read 1062 times)

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Offline Eccentric

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Poulan 3450 3750 and PoulanPro 330 380 Tank Vent Retrofit
« on: January 20, 2014, 06:05:28 pm »
Some folks (myself included) don't like the tank vent setup used on the 3450/3750/330/380 saws.  It can be problematic (sometimes the bronze plug falls out).  It also requires more of the saw to be torn down in order to service the vent (compared to the older style).  Because of this, I retrofitted my PP330 to the vent style used on the 2800/3000/3300/3500/etc saws.  I didn't want to tear half the damn saw down the next time the vent needed service.

This older vent style was also used on the earlier 3400-4000/PP375-395 series.  It works great, and is quick and easy to service without tearing half the saw apart.  The vent style used on the 3450/3750/etc saws does of course still work fine, and I'm sure there are folks that don't see the need for the retrofit.  That's fine too.  Like everything else on the net.........you can take it or leave it.  I've been asked a few times about the details of this retrofit, so here it is.  You'll have to remove the tank/rear handle assembly from the saw to get to the original vent location (or at least disconnect the intake boot, rear AV mounts, and kill switch wires and pivot the tank downwards).  At least you won't have to do all that the next time you have vent issues.

The first shot shows the 3450/3750/etc tank where the original vent (a duckbill followed by a sintered bronze plug) goes.  As part of the retrofit, you'll need to plug this hole.  I selected a suitable self-tapping screw, drilled the hole (where the duckbill went before) slightly to match, put some Threebond 1194 on the screw threads/shank, and then threaded it in.  I pressure/vac tested the tank afterwards (using the fuel pickup line) and it held.

Next step was deciding on a location for the 'new' vent setup.  I picked a spot on the top of the tank (aft of the fuel pickup line hole) where there's a faint circular mark cast in (maybe that's a spot on the mold where the older vent setup went) and drilled it.  This is approximately where the vent hole is on a 2800/3500/etc saw tank.  Think I started with a 1/16" bit.  Debur the edges and clean the plastic shavings out of the tank when done of course.

If the hole's too small (or the line's too thick) the long barb end of the fitting won't pass through the hole.  If the hole's too big (or the line's too thin or has decayed) then it'll leak.  I can't recall the final size drill bit I used for the vent hole on my tank.  You may not use the same size line as I did, so you may well need to drill a different size anyways.  I intentionally drilled the hole 'too small' to begin with, and then kept enlarging the hole until it was 'right'.






Here is the 'double barb' fitting for the earlier style tank vents.  Duckbill (530026119) goes on the short end.  Put the piece of fuel line on the long end and pull it through the hole in the tank (from the inside out).  If the hole and line are the right size, the fitting will butt against the tank wall and the line will make a tight seal between the fitting and the tank. 



http://www.ereplacementparts.com/vent-fitting-p-234906.html




This is the double barb fuel line fitting from a Poulan Micro series saw.  It can also be used in a vent application (I've done so), but that's not it's intended purpose.  It has 'equal length' barbs that are meant to have a fuel line on each end.  Doesn't have a short end for the duckbill and the longer end (with less pronounced barb ridges) for passing through the tank wall.  Works well enough though.  It's a shade more expensive than the 'right' part, but is fine to use if that's all ya got.  I used one as I had a Micro parts saw laying around at the time...

http://www.ereplacementparts.com/fuel-line-fitting-p-236335.html



The 530026119 duckbill valve is a current Poulan and Husqvarna part #, as that valve was (and still is) used on some Husqvarna machines.  Your dealer should stock it.  The double barb fitting they can order.  The Micro application fitting can also be ordered through them, and may be in stock as the Husqvarna 23 was a Poulan Micro in orange clothing. 

You can use the Homelite 69451 duckbill (as used in many Homelite gas caps and also in the oil and fuel tanks of an XL2/Super2) here as well.  It may be too loose for the 'correct' double-barb fitting..............but is a good fit on the Micro double-barb fitting.  Those duckbills are still sold through Oregon and Stens dealers.

After you finish doing this vent retrofit, you just tuck the end of the vent line somewhere alongside the left side of the carburetor, making sure i'ts out of the way of the throttle link and such.  Make sure it doesn't get pinched by the AF mount/divider thing when you install that on top of the carb studs.  Next time you need to service the vent line (to replace the duckbill and/or the vent line) you only have to remove the gas cap, and remove the AF mount divider from the carb studs to get to everything.
-Aaron

For older saws:
Tune the H side so that it 4-strokes (burbles) at WOT unloaded and just cleans up when under load.
When you lift cutting load, the saw should immediately revert to 4-stroking.  Fine tune the transition point for the wood you're cutting.

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Offline Tractorsaw1

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Great help thread thanks for taking the time!

Offline Eccentric

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Great help thread thanks for taking the time!

You're welcome.  I mostly cut/pasted stuff from a few earlier threads and fleshed it out where needed.  It's a bit wordy (my style I guess), but it'll do the job....8)
-Aaron

For older saws:
Tune the H side so that it 4-strokes (burbles) at WOT unloaded and just cleans up when under load.
When you lift cutting load, the saw should immediately revert to 4-stroking.  Fine tune the transition point for the wood you're cutting.

Offline 3000 FPS

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Nice, some great information there.  Thanks Aaron.
PP 505, 475, 445.

Offline Tractorsaw1

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Aaron, is there a part# for the small brass piece that goes in the new line that dangles at the carb?  I am going to stock up on these bits, appears the brass piece is NLA, maybe the one i have is different than #103 on the exploded view?  Or is this piece optional?


Offline 660magnum

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It looks like a screw with a orifice hole drilled through the center?
We should share what we know... someone may learn...
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Offline Tractorsaw1

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the one I have at the house was like small round piece with real small holes in it, lets air in, but not dirt, or gas out?  Fits inside the fuel line & doesn't really look like whats on that break down, maybe its off another saw, brass centered piece or something like that.

Offline Eccentric

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That piece is optional......and unneeded in my opinion.  Was never used on the many thousands of 3400-4000/PP375-395 saws.  They all had this same style of vent.  I didn't use one on my PP330 when I refitted it either.  I just left that end of the line cut at an angle on my saws.
-Aaron

For older saws:
Tune the H side so that it 4-strokes (burbles) at WOT unloaded and just cleans up when under load.
When you lift cutting load, the saw should immediately revert to 4-stroking.  Fine tune the transition point for the wood you're cutting.

Offline farmboy

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That piece is optional......and unneeded in my opinion.  Was never used on the many thousands of 3400-4000/PP375-395 saws.  They all had this same style of vent.  I didn't use one on my PP330 when I refitted it either.  I just left that end of the line cut at an angle on my saws.

I reuse it if it's still there.  If not no big deal IMO.  I think I only have 1 out of 10-12 that has it installed. 
Shep

Offline Cut4fun

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The 2700 I just got in trade. 1st thing I did was pull all the lines, tank vent and fuel were all wrong. Will pull impulse line later to replace.

Just for learning. The fuel line was run through the tank vent area hole (forward hole) and fuel line was cut in half with plastic nipple installed on wrong side of tank. It goes inside tank with duckbill valve inside tank then line running up over behind carb area to make up tank vent.

The fuel line goes in rear hole with one line to carb. 

Least all of the ones I paid attention to have been this way. I even pulled to check the grey 3.0 3000 down beside it to make sure.
REDNECK Saw Repair

 

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