Makes no sense. What am I missing

[ebinmaine 67,605]

Wow

[stevasaurus 22,764]

Mike, can you take some good pictures of that camshaft, together and apart??  Show the marks and how it goes together, so we all can better understand what happened and what to look for??  

   Get in touch with Shynon for anything you need...that governor shaft with the flag should be easy.

 

I think you can be sure the cam lobe was on wrong.  It had to be.  

[squonk 41,153]

First picture is from Brian Millers site. He shows how to line up the points cam:

 

I do not see a dot. But you can just make out an arrow where my finger is. The cam can only go on 2 ways so this must be the mark:

 

 

The punch mark on the points cam lines up with the arrow (finger)

 

Picture of the camshaft without the points lobe, I think the tiny spring finger thingy's go inside the slots of the points lobe.

 

 

Points lobe:

 

[squonk 41,153]

My big question is do the springs go inside of the slots or outside of the points lobe? 

 

I have a parts engine here.  Now I know what to look for ,maybe I can determine where they go. Might as well tear it down. I can probably get the gov arm and cam washer out of it

[formariz 11,987]

What prompted you to buy a "rebuilt" engine from an unknown source without it being tested in front of you? Was the price worth the risk? I have also made similar blunders so now its only Charlie @clintonnut  for Clintons and Paul @oldredrider for Kohlers. I know there are other good builders out there but I feel comfortable with the people that I know and trust. Can't put a price on peace of mind.

[Gregor 4,846]

Just out of curiosity, could a one piece cam be substituted for the 2 piece, the engine assembled correctly, and all be good?

 

[squonk 41,153]

4 minutes ago, formariz said:

What prompted you to buy a "rebuilt" engine from an unknown source without it being tested in front of you? Was the price worth the risk? I have also made similar blunders so now its only Charlie @clintonnut  for Clintons and Paul @oldredrider for Kohlers. I know there are other good builders out there but I feel comfortable with the people that I know and trust. Can't put a price on peace of mind.

Ad was for a rebuilt engine along with a parts engine on FB. Ad said "engine will run" When they brought it to the show they tell me they couldn't get it to run. Should have demanded my money back but it probably wouldn't have done any good. I know these 8's are starting to get scarce and I knew someone who needed one. Thought I'd do a favor and sell it for cost to help him out. Lesson learned. I did get 2 good carbs out of it and probably 2 good cranks, 2 good blocks and 1 new rod and piston. If I don't put this together, maybe someone will need some of this down the line and defer some of my cost

[squonk 41,153]

1 minute ago, Gregor said:

Just out of curiosity, could a one piece cam be substituted for the 2 piece, the engine assembled correctly, and all be good?

 

Probably could. I have another engine here for parts. I am going to tear it down at some point and see what's good in it. I really only need the gov. arm and the cam washer

[buckrancher 2,679]

20 minutes ago, squonk said:

My big question is do the springs go inside of the slots or outside of the points lobe? 

 

I have a parts engine here.  Now I know what to look for ,maybe I can determine where they go. Might as well tear it down. I can probably get the gov arm and cam washer out of it

outside of point lobe and yes you can change to the acr cam

[stevasaurus 22,764]

One thing about changing from 2 piece cam to 1 piece cam, the exhaust tappets are different lengths.  I am not sure if anything else is involved.  Maybe when Mike opens up the other engine, it is the 1 piece cam shaft.  

 

Great pictures Mike...thank you.!!!  

[Handy Don 12,235]

1 hour ago, squonk said:

My big question is do the springs go inside of the slots or outside of the points lobe? 

 

It seems like the springs' job is to pull the spark advance arms into the center and rotate the lobe to "retard" the timing (i.e. against the direction of the rotation arrows) while the engine is starting.  Then once at speed, the arms would push outward against the springs and rotate the lobe to "advance" the timing (i.e, in the direction of the rotation arrows).

So the tension on the springs at rest should be pulling the arms inward.

It looks like the hooked end of the spring rests against the outside of the arm and the slightly bent end will be on the opposite side of the camshaft resting against the outside lobe body at the cam gear end. Getting them in place and then inserting the lobe seems like a three-hand job!

Clever bit of design and engineering there. Of course it assumes correct assembly. Great pictures and play-by-play @squonk--thanks!

 

Edited July 13, 2021 by Handy Don

[buckrancher 2,679]

you can do the spring placement with two hands just pull the one spring with one finger and push the point lobe against the other spring to position it then release the spring from under your finger

[squonk 41,153]

And then hope the lobe doesn't fall off when you go to install it.

Edited July 13, 2021 by squonk

[squonk 41,153]

That deal not getting the governor gear out bothered me. I figured that little shaft was supposed to move. Went out this morning and sure enough with a screwdriver I was able to get it to move. Got it out and it's rusty. Beginning to think to this engine sat outside for a while.

[ebinmaine 67,605]

Forgive my bad memory but did you mic the bore?

I was just wondering to myself how close to bore size that nice new piston is....

[Ed Kennell 38,224]

20 hours ago, squonk said:

I think the tiny spring finger thingy's go inside the slots

Makes cents....seems like that's the only way it would work.    Thanks for the info and education Mike.   Old Edog is still learning.

[Handy Don 12,235]

5 minutes ago, Ed Kennell said:

Makes cents....seems like that's the only way it would work.    Thanks for the info and education Mike.   Old Edog is still learning.

I think the slots on the one end of the cam lobe cylinder are only for the little inward-facing arms that actually rotate the lobe cylinder. Putting the spring in there with the arm could cause interference (and not sure they'd fit with the shaft inside anyway). But you are there with it and I'm here at my desk with pictures only! Please post a pic when you get there, and thanks for sharing your progress.

[squonk 41,153]

1 hour ago, ebinmaine said:

Forgive my bad memory but did you mic the bore?

I was just wondering to myself how close to bore size that nice new piston is....

Haven't yet. Still cleaning things up. It's going to need a valve job so I need to check that bore before it goes to the machine shop. And probably won't send it anywhere until I get the other engine torn down to see if any parts I need are usable from it 

[squonk 41,153]

Read buckrancher's post above about the springs. You can see the curve in the springs that go around the lobe on the outside.

[Handy Don 12,235]

@squonk, I think the spring has to end up where the yellow lines are in this picture. One end against the outer arm and the other end agains the lobe cylinder. It's the only way there will be good spring tension on the arm.

[squonk 41,153]

Put the springs on the outside and took a video on how the advance weights work.

 

 

 

 

 

Edited July 14, 2021 by squonk

[Handy Don 12,235]

9 minutes ago, squonk said:

Put the springs on the outside and took a video on how the advance weights work.

 

Thank you @squonk! Great to have this documented on the forum.

The ingenuity of having the arm's weight being pulled outward or sprung inward to cause the points lobe to rotate impresses me. Simple components, relatively easy to manufacture and assemble, and only the lobe cylinder itself is a precision part. How many degrees of retard/advance to you estimate it gives?

[Gregor 4,846]

21 minutes ago, squonk said:

Put the springs on the outside and took a video on how the advance weights work.

 

So I see how they function. What do they do exactly?

[stevasaurus 22,764]

When you 1st start cranking the engine, those weights will turn the cam that the points shaft rides on so that the points open a touch sooner then they normally would.  It advances the spark and thus helps the engine to turn easier...in other words, the spark happens a touch before full compression.  Once the engine starts and rotates fast enough, the weights go back and the advanced spark is normal again.  

[Handy Don 12,235]

 

17 minutes ago, Gregor said:

So I see how they function. What do they do exactly?

 

The key is that the lobe that moves the points rotates on the camshaft rather than being in a fixed position (hence the 2-piece cam name). The purpose of the rotation is to automatically change the timing of the points opening from when the engine is at rest and starting to when it is running from slightly retarded to more advanced.

 

The arms and springs govern the rotational position of the points lobe on the camshaft. When at rest, the springs pull the arms in toward the center and the little arms that engage the points lobe rotate it backward, against the camshaft's rotation, to retard the timing. When spinning, the arms pull outward against the spring and rotate the points lobe forward, with the camshaft's rotation, to advance the timing.

Edited July 14, 2021 by Handy Don