More on B timing woes

[Nathaniel Watts]

I have removed the governer housing and found the marks on the crank and cam gears to be in time. The book says that when the flywheel is timed on left exhaust open that the .020 tappet gap should be closed and the valve just starting to open. When I reach this mark, the left ex. valve is exactly fully open. Which is correct? I removed and checked the flywheel location as per the genuine JD service manual and it was correct. Just wondered if the cam gear could have been installed on the cam in the wrong place by a former owner/mechanic. I have never removed the gear from the cam but also do not know if the marks were aligned befor I dissasembled the engine.

 

[John T]

Nate,

You ask:

I have removed the governer housing and found the marks on the crank and cam gears to be in time.

When you remove the govenor, thats the cam gear you see up top, and you time the govenors gear to it...... Of course, YES the cam needs timed correctly to the crankshaft also

YOU STATE:

The book says that when the flywheel is timed on left exhaust open that the .020 tappet gap should be closed and the valve just starting to open. When I reach this mark, the left ex. valve is exactly fully open. Which is correct?

THE BOOK IS CORRECT,,,,,IFFFFFFFFFFFFFF the Flywheels on the correct crank spline, when its Left Hand Exhaust timing mark is at 3 o clock, INDEED the left exhaust valve should just be ready to start to open NOT full open as you describe THAT TELLS ME EITHER THE CAM TO CRANK TIMING IS OFF OR THE FLYWHEELS NOT ON THE CORRECT CRANK SPLINE

Iffffffffffff the flywheels on the correct crank spline and ifffffffff the cam is timed to the crank and iffffffffffff the cam is timed to the govenor gear alllllllll correct.........

When the flywheels Left hand exhaust is at 3 o clock the LH exhaust should just be ready to open,,,,,,and when the flywheels left hand impulse is at 3 o clock the open female drive slot in the govenor shaft end (where mag mates) shuld be flat horizontal fore n aft.

Then the clutch drive disk must also be on the correct crank spline over on the other side or she will vibrate bad


John T

 

[Nathaniel Watts]

I know which gears are which. The cam gear IS timed to the crank gear. The crankshaft also has a small set screw that will only go in one place and that means there is only one way the flywheel will go one it. When my flywheel is at left ex. the valve is all the way open. Could the gear on the cam be installed wrong causing the valve setting not to align with the flywheel timing mark?

 

[jd b puller]

(quoted from post at 23:27:54 05/18/09) I know which gears are which. The cam gear IS timed to the crank gear. The crankshaft also has a small set screw that will only go in one place and that means there is only one way the flywheel will go one it. When my flywheel is at left ex. the valve is all the way open. Could the gear on the cam be installed wrong causing the valve setting not to align with the flywheel timing mark?

Nathanial, to answer your question about the cam gear being in the right spot on the cam, do you understand the basic concept of how the valvetrain interacts with crank position? Not meant to insult you, but if you understand this, take the spark plugs out and roll it over. Do the actions make sense?

The flywheel will be at "LH IMPULSE" twice per cycle. LH impulse is where TDC is, now, keep in mind, it's TDC on both compression and exhaust strokes. Is #1 plug firing at LH impulse?

http://www.howstuffworks.com/engine1.htm

 

[Nathaniel Watts]

Nope, your right , they don't. Whats your take on the cam gear?

 

[Jake Winn]

So, i have a question for you, when #1 is on TDC of the compression stroke, are both rocker arms loose? If not, the cam is out of time. One other thing to check is in this position, the cam lobes for #1 should be facing rear with the exhaust lobe in the lower position, and the intake in the upper. Both should be at approx the same angle, above and below the centerline of the came, IE- approx exhaust 30 degrees below and intake 30 degrees above.

Check this and see where you are at. Let us know what you find. Any information is good to share. It may help someone down the line.

 

[Mike M]

Back to that statement about "I have removed the governer housing and found the marks on the crank and cam gears to be in time"

You have to remove the crankcase top access cover then peer down in at the inside edge of the crank gear and cam gear to find the timing marks. The crank is in an odd spot for this also. It is not at TDC or BDC Has this been done ?

 

[PBrowning]

YES! You will need to pull the crankcase cover to verify whether or not the cam gear mark and the cam shaft mark are in register. 'Could be where your grief is. (PatB)

 

[John T]

You say "the cam gear is timed to the crank" but its obviously NOT orrrrrr its installed wrong because when its timed RIGHT (assuming flywheels on correct crank spline)

when the flywheels Left Hand Exhaust is at the 3 0 clock mark THE LEFT EXHAUST VALVE SHOULD BE READY/STARTING TO OPEN

Re set the cam to crank timign in such a positiion AND THEN ITS TIMED RIGHT.......but it is NOT currently

Best wishes, hope this helps

John T

 

[Nathaniel Watts]

Nope jake your right, I took the bolts out of the cam gear this morning and gave the cam a 1/3 turn till the holes lined up again and guess what... PROBLEM SOLVED. If anybody has a reasonable explanation how you can mount a late styled B flywheel on the wrong spline I'd like to hear it. Its Impossible if you have the set screw installed in the crank because there is only one spline deep enough on the flywheel to slide over it.

 

[PBrowning]

Nathaniel -- Way to Go!!! I am so pleased for you. Have a Great One!! (PatB)

 

[Duane Larson]

Nathaniel,
I guess I'm lost. If I understand your current setup, your flywheel is not lined up properly with the (missing?) aligning pin, and so is not positioned correctly on the crankshaft. You rotated the camshaft in the cam gear to accomodate the flywheel misalignment problem? If that is the case, the flywheel needs to be properly positioned on the crankshaft or you will have vibration problems as the crank is counterweighted to balance the flywheel when it is properly installed. Maybe I'm just missing something....

 

[Mike M]

I think they can get that flywheel on wrong if they put the setscrewed spline in line with one of the slits in the flywheel hub. I think I saw a model W engine unit that this was done on.