Poulan 3400,3700,3800, 4000 stroked crankshaft project. Part 2

[dieselfitter]

I brought the crankshaft to a friend to be tig welded. After welding, run out was about .020". I got it straightened. Run-out on one side is .0015" the other side is .002". It's more true than the new Chinese 395 crankshaft it checked. I cleaned up the epoxy and primed the case halves. Tomorrow, green paint. Then, final (I hope) assembly of the crankcase.
When I pressed the crankshaft shaft into the crank half, I mis-positioned the flywheel key slot. I have a stock 3400 that I will put a degree wheel on, hook up a timing light and spin over to find the base timing. I will hook up a timing light to the stroked engine and dial it in.

 

[jeepsnchainsaws]

This is #1BMF! I'm gonna name it Poulanstien!

 

[Wolverine]

Song befitting this creation:

My vote for a name:

Takes a lot of time to snap pics and post them, all your time is appreciated. Awesome so far!

 

[Dub11]

Man I was just think that earlier The Super Freak !!! gots my vote

 

[Frank bierce]

Song befitting this creation:

My vote for a name:

Takes a lot of time to snap pics and post them, all your time is appreciated. Awesome so far!

 

[dieselfitter]

The idea for this saw came to me after watching a movie about this kid named Luke, he had this thing called a "light saber". It was awesome, it would cut through anything with the flick of the wrist. After watching the movie, I started looking around for something to make one.
Anyhow, I'm busy watching the paint dry.

 

[dieselfitter]

Guess which saw is higher displacement.

 

[Dub11]

So I think at this point in time is how long will this thing run with that tiny gas tank? Might have to rig up a backpack tank? And MAY THE FORCE BE WITH YOU.

 

[Tractorsaw1]

Awesome build - I want hack on my 3800 now!

 

[Mastermind]

I was scratching my head for a while trying to figure out how to do that one. I measured the two different patterns and sketched it out. The two patterns overlapped each other but neither pattern could be moved enough to match the other. I needed to come up with a 3 pattern for the adapter to case that:
1 didn't move too far from the original(the casting gets thin).
2 didn't overlap with the cylinder mounting pattern.
3 didn't interfere with the cylinder skirt protruding down below the cylinder mounting surface.
It got too confusing to sketch out because it was too much work to maintain scale of the drawing to monitor the relationship of everything. I downloaded an autocad program and learned enough of it to get it done. Another difficulty was getting all the numbers to jive in the autocad drawing. Measuring the cylinder mounting holes, they would vary by .003" in location. Not having access to the manufacturer's drawing or dimension, I'm trying to figure out what it is by measuring the part and the measurements are all over the place. I had to manipulate the dimensions(radius, bolt spacing) within autocad drawing until the numbers jived.
Once the numbers jived, I moved the new spacer block mounting screw location to a location that put them equally distant from the cylinder mounting bolts and the cylinder skirt.
Once the numbers were known, it was just a matter of turning dials to get them on the DRO on the mill.
Another thing I did was change hardware. The original cylinder mounting to case bolts were 1/4" course thread. I had considered going to 6mm-1 which is a little smaller(giving me more room in a tight area). I chose #12-24 which is a little smaller yet and more course of thread.
View attachment 45774 View attachment 45775 View attachment 45776 View attachment 45777

I'll send you a Foredom. I have an extra.

 

[t4driller]

Wow is all I can say!!

 

[dieselfitter]

I'll send you a Foredom. I have an extra.

Don't. I'll buy one. Thank you for the offer. I have been incredibly blessed to have the resources I have. Better your Foredom go to someone else more deserving.

 

[Tractorsaw1]

I been out cutting firewood this am & was hoping the updates meant it was running - the paint is dry?

 

[dieselfitter]

Primer is dry. I'm between coats of "Sublime Green"

I checked base timing on a stock saw for a point of reference to time this one during assembly. FTW 25.5*btdc when spinning with my cordless drill.

 

[Mastermind]

Primer is dry. I'm between coats of "Sublime Green"
View attachment 46064
I checked base timing on a stock saw for a point of reference to time this one during assembly. FTW 25.5*btdc when spinning with my cordless drill.

Did you use a inductive timing light Tim?

 

[dieselfitter]

Yep. I had problems with my timing light. Had to borrow a friends. Neither of us could remember the last time we used a timing light. Pretty much an obsolete tool nowadays.
Has anyone ever had problems advancing the timing on this particular model of saw? I have tried advancing the timing on 2 of these saws with no luck. Both wouldn't start and acted like retarded timing. Yes, I advanced the timing and didn't retard it.
I've wondered if this stock Poulan ignition will work at rpm's higher than stock. They don't spin very fast stock.
Randy, did you get more RPM's out of Jon's 4000 when you ported it? Any ignition problems that limited rpm?

 

[Mastermind]

Yep. I had problems with my timing light. Had to borrow a friends. Neither of us could remember the last time we used a timing light. Pretty much an obsolete tool nowadays.
Has anyone ever had problems advancing the timing on this particular model of saw? I have tried advancing the timing on 2 of these saws with no luck. Both wouldn't start and acted like retarded timing. Yes, I advanced the timing and didn't retard it.
I've wondered if this stock Poulan ignition will work at rpm's higher than stock. They don't spin very fast stock.
Randy, did you get more RPM's out of Jon's 4000 when you ported it? Any ignition problems that limited rpm?

I've done a few 4000s.......and they turned up very well. No ignition worries, and plenty of rpm.

 

[Jetmd]

COOL thread!!

 

[rocketnorton]

lookin good, tim.

 

[dieselfitter]

Not a very productive day. The new supplied crankshaft bearings are caged. I'm disappointed. I clearly told that jackwagon I want full compliment. For those unfamiliar with this saw model, these saws use a needle crank bearings. Here's a pic of caged and full comp for comparison.

I did chase threads on the case halves and start mounting stuff.
Thanks to Tim/Fossil for helping me with some oil pump diaphragm material and support and advice on this project.

I learned something new today I didn't know about these saws. I haven't checked parts books to see if the is a s# break or what determines which plug any given saw would use. There seems to be early and late bore oil caps. I'm guessing early being smaller than late. As luck would have it, the random case half I used is for the small plug and I don't have any small plugs. A Briggs & Scrapiron oil cap kinda fits for now.
I roughed out the carb mounting block.


I'm Hoping Adam will finish it. He has agreed to do the porting. Adam has been the brains behind this project. My contribution has been to make it bolt together. I know nothing of porting at this time. It is something I hope to learn.