Valve Timing

1945 - 196*, Willys CJ series, questions, discussions, regarding anything related to the post war jeep.®
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cpiunno
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Valve Timing

Post by cpiunno » Thu May 25, 2017 3:40 pm

I just finished putting together this engine, and when rotating the crank clockwise using a socket on the bolt on the cam gear I noticed the the exhaust valve is opening on the decompression stroke. This is 180 degrees out of phase. There is no way to improperly install the cam gear and the crank gear, they are both keyed and have dots that line up. Take a look at the pictures. What am I doing wrong?
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Wolfman
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Re: Valve Timing

Post by Wolfman » Fri May 26, 2017 5:02 am

If the dots are still together in the second picture, with the piston in the position it is in, something is definitely wrong.
I have run across cam gears that had the dot in the wrong place. Don't think I have ever seen a crank gear miss marked.
Scrap the original marks.
Start by putting the crank in a position so # 1 piston is on TDC. Mark the crank gear.
Then put the cam gear in a position so #4 valves are rocking and evenly open. Mark the cam gear.
Now put the engine together with the new marks you just made.
Life should be good.
After thought.
I have seen engines where, when the marks were originally timed together, the cylinder was not on TDC but when the crank was turned to TDC the valve timing was correct, but never on an L-134 jeep.
When you bring the piston up to TDC, what are the valves doing ???
If the valve operation and piston position are correct with the marks you have, life is still good, even though the marks are not where they normally would be.
Mike Wolford
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Sean Collins
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Re: Valve Timing

Post by Sean Collins » Fri May 26, 2017 7:55 am

cpiunno wrote:... when rotating the crank clockwise using a socket on the bolt on the cam gear ...
Very confusing! If you are rotating the cam gear clockwise, that is the WRONG direction.

With gear-drive: crankshaft rotates clockwise, camshaft rotates COUNTER-clockwise.

Why are you using the cam bolt? Always use the crank nut clockwise.

When the dots are lined up, are #1 and #4 pistons at TDC?

If so, #1 valve should be fully closed, #4 valve should be just slightly open.

Continue rotating crank CW. As pistons descend, #4 valve should fully close. As pistons approach bottom of stroke, #1 valve should begin to open.

If not, then the gear marks are not standard. Follow Mikes advice.
Wolfman wrote:... Then put the cam gear in a position so #4 valves are rocking and evenly open ...
This is an F-head, no intake valves.
 

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Re: Valve Timing

Post by Joe Gopan » Fri May 26, 2017 8:37 am

Something to check if you have swapped cams, check the Willys Part No that is stamped on the side of the camshaft, it should be 800517, they are unique to "F"- Head.
hope you did not drive the cam gear on with a hammer, it can push out the expansion plug.
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cpiunno
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Re: Valve Timing

Post by cpiunno » Fri May 26, 2017 11:39 am

Sean hit it on the nose. I am a dummy. The cam rotates counterclockwise in normal operation, and I was turning it clockwise thus the crank was moving in reverse. Consider this issue solved. User error. Let's all try to forget this ever happened.
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Re: Valve Timing

Post by Joe Gopan » Fri May 26, 2017 1:02 pm

Your error is not wasted, as it is a lesson in Jeep repair and may prevent another from doing the same. These little things are educational.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
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Re: Valve Timing

Post by Fortyeight2A » Fri May 26, 2017 5:47 pm

I'd like to point out that that is a nice-looking engine!
Is it true real Jeeps have flat fenders?
Alone cannot you it resist!

Wolfman
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Re: Valve Timing

Post by Wolfman » Sat May 27, 2017 5:25 am

Of course there are intake valves, Sean.
Only in this case, they are in the head, not the block. Same, same action weither L or F head.
Since this is an F head, just drop the push rod in the hole. It will act like the intake valve on an L head.
Mike Wolford
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Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
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