billzair

My Feedback: (29)

does any one know off hand what degree( s ) the taper part of the crank on a poulan 46 is? (were the key sits)

also I believe the threads are 8mm x 1.00 but when I scew on my prop hub it seems a
little sloopy.

Thanks

combatpilot

I dont know bout this engine but on a ryobi it is 10 deg. the threads on a ryobi are also standard fine thread. it seems from some of the smaller poulans i have played with the taper and threads were the same. the mag and prop hub off my ryobi would also fit on any puolan and craftsman weedie.

I will have to bet the taper on yours is also 10 deg and the threads are gona be standard thread as they all semm to be the same.

KenLambert

My Feedback: (107)

20 total 10 per side

billzair

My Feedback: (29)

thanks!

rangerfredbob

My Feedback: (13)

the poulan 46 is 8x1, I'm sure of it as I have one and that's what it took to make it fit.

some taps especially if they haven't been used too much will make them a little loose, which is fine as long as they hold tight...

billzair

My Feedback: (29)

The prop hub screws on fine but im driving myself silly here because I got a "wobble " at the end of my prop hub...+/- .004 and I cant figre out were is coming from. I tap my hole while the hub is still in the lathe so...[sm=spinnyeyes.gif]
thats why I want to know what angle the taper is on, so the next hub I make hopefully will have no wobble. The funny thing is, I never had a problem before this engine. Yes the crank is straight...I checked it with a dial indacator.
well see......

KenLambert

My Feedback: (107)

sacrifice an old crank to make a stub shaft and turn everything on the shaft and it will not have wobble

combatpilot

I am gatering that you are using the stock flywheel is this correct? I also was using the stock flywheel and also turned a prop hub and threaded it in the lathe so i know the threads were straight. to my horror also it had some runout when installed on the engine.

After looking at it for a long time i realized that when the flywheel was chucked up in the lathe and the fins where cleaned off that it was impossible to chuck up the flywheel and face it off to where the facing was perfectly purpendicular to the shaft centerline. so when put on the engine and the hub installed and if there is a little slop in the threads the hub will fit itself to the flywheel face that is off just a little.

Ok so to fix this i took a spare crank i had that i didnt plan on using at all. I knocked the shaft off of the counterweight as its just pressed on. when the flywheel is installed on the shaft I now have an arbor that i can chuck up in the lathe and use this to turn the flywheel perfectly prependicular to the shaft.

Just one problem. when it is installed on the shaft you cannot face the flywheel where the prop hub goes because the nut holding it together is in the way. SO the thing to do is leave enough room between the back of the flywheel and the chuck when it is chucked up that the back side of the flywheel may be faced off. this cleaned up surface on the back sidde of the flywheel will now be purpendicular to the the shaft centerline and now you will be able to take the shaft off and mount it in the chuck chucking off of the outside of the flywheel. The new concentric back of the flywheel will rest against the chuck dog face and if your chuck is in good shape and concentric it should maintain the perpendicular plane to the shaft center line. the flywheel may now be faced and shound have a facing that is perpendicular to the shaft center line

this is what i did and it did fix my runout.

captinjohn

If the flywheel has the correct taper as the shaft...it will...and should stay in place without the nut. A little locktie will hold it there in place for the correct timing also. No key is needed. Yup....thtas is a way to advance the timing on a flywheel ignition engine! Capt,n

combatpilot

Why would you want to advance the ignition? a stock ryobi is already at 28-29 degree advance. this is where the electronic ignitions are set to so what good would advancing it do as its been my experience any more is detrimental to power. Some ryobis actually have a retard setting of about 20 degree adv to them and when they hit a certain rpm they advance to 29 degree.

KenLambert

My Feedback: (107)

I was thinking he is cutting a prop hub to fit the crank without the flywheel, seems that would be the need to know the taper other wise you tru the flywheel and screw on a hub no taper needed.

combatpilot

Yea i guess we just dont know enough about his set up or what he is doing. How bout it billzair what is your set up. we need more info lol. pics are great to

billzair

My Feedback: (29)

ok.....
I orginally was using the stock flywheel. I machined down the fins and away i went. I noticed this engine dosent like to be hand started, so i used my 18 volt drill and it started. I noticed while running I could sight down the prop hub and see it move up and down about a 1/8 or so.[:@] I then turnred down another one, this time for E.I. This one aslo has "wobble"....when I dial indicate the hub in the lathe it is .001 os so.
I put the dial indactor on the engine again to double check how true it was.... and the end of the crank is running at .004 !! magnify that with a 2.5 inch prop hud and thats were im getting the 1/8 wobble i believe.

.004 seems like exsessive runout right?
thanks for all the replies guys..

KenLambert

My Feedback: (107)

did you check the crank without the prop hub ? The crank may need some tweeking , if you turn the hub on a stub shat ( crank) and your machine is acurate the bub should have lessthan .002 runout at the end of the hub. You must start with a straight crank and well aligned lathe. If you are going to use the fly wheel mount it on the stub shaft true the flange and mount the hub then machine it and drill the end for the prop bolt. Do all the work in one setup without taking it out of the lathe and it will be straight. Also make sure your lathe doen't have any runout.

Also you may want to use a test indicator instead of a dial.

billzair

My Feedback: (29)

Ken, the lathe is running true..i did test that first. te end of the crankstaft (without the prop hub) is at .004
can I eazily true the crank?.........with a HAMMER[>:] just kidding. Out of all the engines I done, this ones the only one thats been like this. Should of bought an echo, lol.

KenLambert

My Feedback: (107)

I have done several poulans including the 46, just finished one a couple weeks ago, if the cranks is.004 then there will be a lot of wobble at the end of the prop. Take a 5# hammer and beat it to deth and get another crank or you could contact Ralph at RC ignition and see if he will straiten it.

combatpilot

Yea i think without looking at the parts from what your saying im willing to bet that your crank is bent and thats where your getting your runout.

captinjohn