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kayak
Senior Member
Username: kayak
Post Number: 65
Registered: 06-2016
| | Posted on Saturday, November 12, 2016 - 07:51 pm: | 
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For some reason I am paranoid about the cam timing. I did follow the procedure below, and it lines up. Simple enough, at TDC, cam key is pointing forward. When I crank it to start, I hear a pop from the carburetter, and the intake starts to open about 30 degrees before the piston reaches TDC. This could all be normal, as I said, the TDC/keyway indicates correct.
Here is a video which shows and if anyone here has a YT and could turn it and say when the intake starts to open and if the valves look in this position at TDC that would be great! Then there must be another reason I am not able to starting up this engine.
Hopefully also this topic can help others someday.
https://youtu.be/nq8Ph-lhxHg
PROCEDURE - Dick Day
SETTING VALVE TIMING ON THE PALMER BROS. YTI
Richard A. Day Jr. December/January 1998
Setting the cam gear on the YT1
marine engine can be a most difficult problem when tackled for the first time. The gear being spiral means one has to take into account the initial mesh versus the final mesh rotation of the cam. Hopefully the following approach should avoid too
many frustrating attempts to correctly time the valves.
1. The rotation of the YT1 is counter clockwise facing the flywheel. Too many people have tried to start the YT1 or other old time marine engines by cranking them clockwise. The common experience is the engine keeps backfiring and wants to run the other way, NUFF SAID!!
!
2. The water pump eccentric if lightly pressed on the shaft makes a convenient handhold to rotate the cam.
3. Note the key ways on the shaft all line up.
4. Slide the water pump end bushing onto the shaft and then insert the keys in the shaft for holding the cam gear.
5. Note the cam gear key ways are lined up so that the peak of the exhaust valve cam is lined up with its keyway. The intake cam peak clearly does not line up with its keyway. The exhaust cam should be installed toward the water pump eccentric.
For our marine friends the water pump and the exhaust valve are on. the Starboard side of the engine. The intake valve is on the Port side of the engine.
6. If one holds the cam gear in their hand with the keyways facing away and the exhaust cam end toward the right, one should note the intake cam on the left end is in the same relative position as the exhaust cam peak except it faces toward the rear. Rotating the cam gear clockwise (relative to the exhaust cam) should indicate the closing of the exhaust valve immediately followed by the opening of the intake valve.
7. There is often a large overlap in the opening of the typical exhaust valve and the closing of the intake valve. On the other hand most old time, low speed engines with mechanically operated valves are very predictable on the closing of the exhaust valve followed within a few degrees with the opening of the intake valve. For this reason one should work with the closing of the exhaust valve followed by the opening of the intake valve.
8. One can visualize the YT1 cam gear when it is correctly positioned in the engine with the keyway of the water pump eccentric facing forward, the exhaust valve will have just closed and the intake beginning to open.
9. When the flywheel rotates counter clock wise the cam shaft rotates clockwise when viewed from the water pump end of the shaft. The trick is to insert the cam gear with the exhaust cam towards the water pump so when the flywheel is pulled up on TOP DEAD CENTER the water pump eccentric keyway faces forward. There can be no question if one has the gears meshed correctly. Check the position of the piston through the spark plug hole. As the piston comes up on TDC the exhaust valve closes and the intake begins to open. Being off by one tooth in either direction will immediately be obvious. The really frustrating part of the operation is judging how much lead in meshing the spiral gear. Once you know how to determine the exhaust cam end and the final position of the cam shaft keyways at TDC, persistence will overcome one's
doubts!! |
kayak
Senior Member
Username: kayak
Post Number: 66
Registered: 06-2016
| | Posted on Sunday, November 13, 2016 - 02:26 am: |
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May have started to answer this question, I have reviewed my YT run video from before the reassembly and the water pump eccentric has two screws which are perpendicular to the key, and the flywheel has that big pull knob for starting.
Back then, the cam was perpendicular when the start peg was at 5 and 11oclock. NOW, the peg is at 1 and 7 oclock. Also the intake finished opening, and closing about 2 "hours" earlier.
I believe the camshaft is off by a tooth or two.
However, there is no doubt that according to the Day instructions, the cam key is facing due forward when the engine is at TDC. Nonetheless, I will pull the cover and move the cam to match the old photos.
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kayak
Senior Member
Username: kayak
Post Number: 67
Registered: 06-2016
| | Posted on Sunday, November 13, 2016 - 02:28 am: |
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kayak
Senior Member
Username: kayak
Post Number: 68
Registered: 06-2016
| | Posted on Sunday, November 13, 2016 - 02:42 am: |
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one more, matches cam position of first picture (I am tired this time of night)
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ernie
Senior Member
Username: ernie
Post Number: 2337
Registered: 01-2002
| | Posted on Sunday, November 13, 2016 - 07:23 am: |
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Chris,
I was going to suggest checking cam timing when you described your starting problems.
Make sure...MAKE REAL sure that the exhaust valve has just closed and the intake valve is just starting to open at TDC. I have to check but to be exact I think the exhaust closes just before and the intake starts to open just after.
I have the latest instructions from Dick Day but haven't posted them yet as I need to include pics so the instructions are clear and concise. |
ernie
Senior Member
Username: ernie
Post Number: 2338
Registered: 01-2002
| | Posted on Sunday, November 13, 2016 - 08:00 am: |
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This engine is timed as per the pics below.
https://www.youtube.com/watch?v=qjKfoZIii-k
Dick D had an NOS YT1 a while back. I checked the cam timing on it and it was timed as in the pics above.
Chris I need to do a vid of the entire procedure. Do you want to come over and assist? |
kayak
Senior Member
Username: kayak
Post Number: 69
Registered: 06-2016
| | Posted on Sunday, November 13, 2016 - 11:49 am: |
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Hi ernie,
thats a big help
your two pics look different, both appear at TDC but the first pic has the cam at 2 oclock the other looks at 3 oclock (level) but maybe its the angle the pic was taken.
working todey and tomorrow but maybe I can come by with it this week or thereabouts
cp |
ernie
Senior Member
Username: ernie
Post Number: 2339
Registered: 01-2002
| | Posted on Sunday, November 13, 2016 - 12:38 pm: |
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When set properly the crankshaft key-way will be straight down and the camshaft key for the water pump eccentric should be about 2 o'clock. You have to carefully rock the camshaft back and forth to split the difference between exhaust close and the start of intake open. This is where TDC should be.
I have 7/16 bolts on the valve lifters so you can accurately see any movement by looking at individual threads on the bolts. |
kayak
Senior Member
Username: kayak
Post Number: 71
Registered: 06-2016
| | Posted on Thursday, November 17, 2016 - 02:09 am: |
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followed ernie much appreciated procedure above exactly, now it seems properly aligned. hope to start it as soon as possible.
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