Author Topic: Poulan 3400 Counter Vibe modification?  (Read 2734 times)

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Offline 660magnum

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Re: Poulan 3400 Counter Vibe modification?
« Reply #20 on: February 16, 2013, 02:14:05 pm »
That is confusing and you have to pause and think about the relationships sometimes?

I run into this from which side of the engine I'm on and for coil mounting if the engine is right side up or upside down etc if
I'm standing over the engine and not in front of it.





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Offline 3000 FPS

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Re: Poulan 3400 Counter Vibe modification?
« Reply #21 on: February 16, 2013, 02:46:52 pm »
How does the FW stay locked in place with the wider keyway? I read about slotting the coil a bit to advance timing, any experience with that?


Well to advance the timing you turn the flywheel in a clockwise direction.   So I widen the slot on the left side so that it will still rest against that side.   You only need about a 1/16th of an inch to get around 3 to 4 degrees.   I then line up the flywheel where I want it and tap in on with a socket and hammer so that it gets tight on the taper.  Then I tighten it the rest of the way down with a 3/8ths impact gun.    I then double check my timing and make sure it is right and the taper on the fly wheel is actually enough to keep it in place.




To advance timing, the flywheel must go COUNTERCLOCKWISE!
The crank goes clockwise if you are widening the slot in it, you will remove material from the left side.
I always remove from the flywheel. They are easier to replace if you mess up!!!
The engine rotates counterclockwise and to advance, you have to get it there earlier.


Mike


Help me out here Mike.   If I am looking at the clutchside then it is turning clockwise if I am looking at the flywheel side it is turning counter clockwise is it not.
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Offline brokenbudget

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Re: Poulan 3400 Counter Vibe modification?
« Reply #22 on: February 16, 2013, 02:49:58 pm »
you can get and easy 3-4 degrees by sloting the coils mounting holes. there is alot of room.

3000 fps: i found after 185psi you actualy start to loose top end. i try to keep them around the 175-185psi mark. the bottom end will thank you for it as well. ;)

on the air filter cover being slotted, that isn't set in stone. lots of 3700's were sold with either. and more than a few 3400's also. the only real way to know what you have is to look inside.
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Offline brokenbudget

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Re: Poulan 3400 Counter Vibe modification?
« Reply #23 on: February 16, 2013, 02:51:06 pm »
How does the FW stay locked in place with the wider keyway? I read about slotting the coil a bit to advance timing, any experience with that?


Well to advance the timing you turn the flywheel in a clockwise direction.   So I widen the slot on the left side so that it will still rest against that side.   You only need about a 1/16th of an inch to get around 3 to 4 degrees.   I then line up the flywheel where I want it and tap in on with a socket and hammer so that it gets tight on the taper.  Then I tighten it the rest of the way down with a 3/8ths impact gun.    I then double check my timing and make sure it is right and the taper on the fly wheel is actually enough to keep it in place.




To advance timing, the flywheel must go COUNTERCLOCKWISE!
The crank goes clockwise if you are widening the slot in it, you will remove material from the left side.
I always remove from the flywheel. They are easier to replace if you mess up!!!
The engine rotates counterclockwise and to advance, you have to get it there earlier.


Mike


Help me out here Mike.   If I am looking at the clutchside then it is turning clockwise if I am looking at the flywheel side it is turning counter clockwise is it not.

yes. to advance the timing you need to move the flywheel a little more counter clockwise. in the same direction it turns.
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Offline 3000 FPS

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Re: Poulan 3400 Counter Vibe modification?
« Reply #24 on: February 16, 2013, 03:00:44 pm »
Well guys I hate to say it but I am confused on the timing issue.    Can someone please explain to me the theory behind why you move the flywheel counter clockwise.    I thought advancing  the timing meant you were increasing the time from top dead center of the piston in relation to when the spark is generated.    In other words the spark always occurs in the cylinder after top dead center so that you get spark as the piston is traveling down and not before.   So If you delay the spark by a few degrees you get more power out of the stroke because it is now occuring closer to top dead center but still on the down stroke.
PP 505, 475, 445.

Offline man of stihl

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Re: Poulan 3400 Counter Vibe modification?
« Reply #25 on: February 16, 2013, 03:11:10 pm »
Well guys I hate to say it but I am confused on the timing issue.    Can someone please explain to me the theory behind why you move the flywheel counter clockwise.    I thought advancing  the timing meant you were increasing the time from top dead center of the piston in relation to when the spark is generated.    In other words the spark always occurs in the cylinder after top dead center so that you get spark as the piston is traveling down and not before.   So If you delay the spark by a few degrees you get more power out of the stroke because it is now occuring closer to top dead center but still on the down stroke.
When you advance the timing. (Moving the flywheel counter clockwise) means the plug will fire sooner.
Ron

Offline 3000 FPS

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Re: Poulan 3400 Counter Vibe modification?
« Reply #26 on: February 16, 2013, 03:56:28 pm »
Well guys I hate to say it but I am confused on the timing issue.    Can someone please explain to me the theory behind why you move the flywheel counter clockwise.    I thought advancing  the timing meant you were increasing the time from top dead center of the piston in relation to when the spark is generated.    In other words the spark always occurs in the cylinder after top dead center so that you get spark as the piston is traveling down and not before.   So If you delay the spark by a few degrees you get more power out of the stroke because it is now occuring closer to top dead center but still on the down stroke.
When you advance the timing. (Moving the flywheel counter clockwise) means the plug will fire sooner.


Ok using the information that the plug will fire sooner and put it into theory for myself it now makes sense.   I had it wrong thanks for the correction.   

I had this written down because of the confusion and did not bother to look at it this time.  My bad.
PP 505, 475, 445.

Offline 3000 FPS

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Re: Poulan 3400 Counter Vibe modification?
« Reply #27 on: February 16, 2013, 06:05:28 pm »
Taking a saw from 4* retarted to 4* advanced seem to make it run stronger. ;D    Now I am going to have to go back and look at the last saw I changed the timing on to see if I looked at my notes.
PP 505, 475, 445.

Offline 3000 FPS

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Re: Poulan 3400 Counter Vibe modification?
« Reply #28 on: February 16, 2013, 06:16:30 pm »
you can get and easy 3-4 degrees by sloting the coils mounting holes. there is alot of room.

3000 fps: i found after 185psi you actualy start to loose top end. i try to keep them around the 175-185psi mark. the bottom end will thank you for it as well. ;)

on the air filter cover being slotted, that isn't set in stone. lots of 3700's were sold with either. and more than a few 3400's also. the only real way to know what you have is to look inside.

Thanks for the info on the compression.

As far as the filter cover goes, it is not an absolute only because anybody can switch them around anytime they want.   I always look for the thin rings on the piston before determining what it is.
PP 505, 475, 445.

Offline jcsmith

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Re: Poulan 3700 filter cover
« Reply #29 on: February 16, 2013, 10:07:08 pm »
Hi fellers,   On my craftsman 3.7 (3700) , all original, it does not have the slotted cover. ??? And speaking of thin rings, what exactly is the significance?  Appreciate any info.  Chris
Chris

 

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