Poulan 3700 rebuild

[walcen]

Hi folks, This is my first post on this forum and having read through a few threads I think I'm in the right place.
I was given an old one owner home use only poulan 3700 with low comp, 80 psi if that. a complete strip down revealed that the chrome bore and piston are in very good condition however the ring gap is 100 thou, yep you heard right 2.5mm. I'm happy to post pics of my little adventure if any one is interested but I can't find piston rings. there are two thin ring roughly 24 thou.
Any help would be great, thanks in advance and kindest regards,
Walt

 

[ammoaddict]

I would love to see pictures of your build. Hopefully someone can help you find some rings. Good luck.

 

[Thesandman]

I might have a set. I was sent wrong rings for my 4000 and still have them. On my way to work so I will check tomorrow evening. They were too small for 4000.

 

[walcen]

Thank you for your reply guys, I'm sorry for the late come back but I've been away for the week end. Did some one say rings?? . I'll put up some pics tomorrow.

 

[walcen]

Okay, So as I stated, this was a one owner saw and the owner tells me that it has never been in for any major repairs, so one must ask, Why is the inside of the oil reservoir coated in epoxy? Maybe from factory? I was thinking of grinding it out just to see what was going in there but I don't want to open a can of worms. Any thoughts?

You'll notice that I've surfaced the case halves, there was no casket only sealant and I could see specs of day light between them after unbolting and cleaning them, I know the bolts would pull them together but I like to avoid unnecessary stress. Also it'll reduce the 10 thou crank end play.

 

[walcen]

Here is a pic of the ring gap, yeah you could drive a Mack through it.

 

[walcen]

The piston ring are very thin, I've added some pic of the measurements. I believe there's a couple of different rings for this model saw.

 

[walcen]

I might have a set. I was sent wrong rings for my 4000 and still have them. On my way to work so I will check tomorrow evening. They were too small for 4000.

Hi Sandman, I was just wondering if you ever found that set of piston ring, if so, I'm happy to pay cost and postage ,regards, Walt.

 

[Thesandman]

I can't find it. I'm not sure now I didn't throw it away. That's not like me though so it might turn up someday. I will try to clean off my bench soon.

 

[walcen]

I can't find it. I'm not sure now I didn't throw it away. That's not like me though so it might turn up someday. I will try to clean off my bench soon.

That's okay, don't sweat it, and thank you.

 

[walcen]

Hi folks, I hope all is well with everyone.
Time for a little up date me thinks.
I posted a question on the help part of the forum regarding crank shaft end float specs as mine was over 20 thou and this saw utilizes thrust washers. On my first inspection I thought that the washers ran up against the casing as that's where they sat until this person

67L36Driver "Thanks"​

mentioned driving the McGill drawn cup needle bearing a tad deeper. this switched on the light bulb as I realize that the thrust washer was intended to ride against the bearing but was too worn to do so, Doh!!!, So I did what any retied fella with a lathe and a sh%t load of time on his hands would do, went and bought some bronze round stock and machined up come new thrust washer leaving about 6 thou end float for oiling.

​

 

[walcen]

Now I need to decide if want to grind away at the barrel where it bolts onto the crank case. I'll check my numbers first and go from there.
Any advice in this type of cylinder would be appreciated.
Thanks in advance,
regards,
Walt.

 

[walcen]

Okay folks, here are my timing numbers with and without the base gasket. Any input would be appreciated, Thanks.

Yes I painted it in cammo, anything is better than that sh$ty green.

Timing Numbers with base gasket.

Squish = 1.4mm / 0.055.

Exhaust opens @ 99º atdc Duration =162º

Transfers open @123º atdc Blow down =24º

Intake opens @ 64º btdc Duration =128º



Timing Numbers without base gasket.

Squish = .83mm / 0.032.

Exhaust opens @ 100º atdc Duration =160º

Transfers open @ 124º atdc Blow down =24º

Intake opens @ 65º btdc Duration =130º

 

[Maintenance Chief]

N

Hi folks, I hope all is well with everyone.
Time for a little up date me thinks.
I posted a question on the help part of the forum regarding crank shaft end float specs as mine was over 20 thou and this saw utilizes thrust washers. On my first inspection I thought that the washers ran up against the casing as that's where they sat until this person

67L36Driver "Thanks"​

mentioned driving the McGill drawn cup needle bearing a tad deeper. this switched on the light bulb as I realize that the thrust washer was intended to ride against the bearing but was too worn to do so, Doh!!!, So I did what any retied fella with a lathe and a sh%t load of time on his hands would do, went and bought some bronze round stock and machined up come new thrust washer leaving about 6 thou end float for oiling.

​

Nice work.

 

[walcen]

N

Nice work.

Thank you for chiming in, I was beginning to think I was in a cemetery, all I could hear was crickets lol.

 

[Maintenance Chief]

Well sometimes the old saws don't get alot of attention. The poulan thread is a good place the showcase your handy work though.

 

[Gullet]

Thank you for chiming in, I was beginning to think I was in a cemetery, all I could hear was crickets lol.

Forum seems to be slower as of late.
Nice job!

 

[walcen]

Hi folks, hope all is well with you all.
I thought I'd touch on a subject regarding the fuel tank on this saw and others like it. I found a youtube channel where a fellow was discontent with the fact that the fuel tank cap had swollen and was difficult to remove.
In my case the tank had swollen and the cap would not screw on tight enough to seal.

I fixed this issue by heating the tank filler neck with a heat gun and then sliding an aluminum ring over it to prevent it from swelling again. This fix worked out very well, you could use PVC pipe to do this as well.

Thanks for chiming in Gullet.

 

[9050lx]

I had an old Husquvarna (345, I think), gas cap, that screwed right on in place of the Poulan gas cap and doesn't leak.

 

[walcen]

I had an old Husquvarna (345, I think), gas cap, that screwed right on in place of the Poulan gas cap and doesn't leak.

Gday there, thanks for dropping in. That's handy to know however this saw was probably left in a sunny spot for a long time and the tank was so expanded that the cap could be rotated over it's own thread.