Hello I am trying to verify that the valve timing is correct on my 2510 diesel that I am putting the head back on. This is the one that had intake valves in place of exhaust, so they were rubbing against the cylinder wall and had to be closed by the piston on the exhaust stroke. Is the exhaust valve supposed to close right at TDC of exhaust stroke, or a few degrees before? Just making sure that timing was not also part of the reason I have very shallow valve-shaped impressions on the top of all pistons.
- Thread starter Ray IN
- Start date
I don't know how it happened, but I knew it was something of a gamble to buy a "rebuilt" engine off the internet. The price was right, and the rest of the engine seems to be ok so far. It just had excessive valve noise and then it broke the keeper end of one of the valves. Didn't drop into the cylinder, fortunately.
Did all the valves leave marks or just the offending valves in question?
Something else that should be checked is valve protrusion or recession, I'm not 100% sure one the 300 series Deeres.
As far as valve timing goes you really need a degree wheel to check it accurately, you could print one off the internet and use magnets to hold it on the front pull with a wire pointer to get close enough. Cam timing should be measured from the cam with a dial indicator off a push rod if possible. Just an educated guess based on stock Deere 466 valve timing, the exhaust lobe should be at 0 lift or nearly 0 at TDC on the exhaust stroke.
Something else that should be checked is valve protrusion or recession, I'm not 100% sure one the 300 series Deeres.
As far as valve timing goes you really need a degree wheel to check it accurately, you could print one off the internet and use magnets to hold it on the front pull with a wire pointer to get close enough. Cam timing should be measured from the cam with a dial indicator off a push rod if possible. Just an educated guess based on stock Deere 466 valve timing, the exhaust lobe should be at 0 lift or nearly 0 at TDC on the exhaust stroke.
All four exhaust valves left impressions on pistons. New valves my machine shop put in are smaller and recessed just
slightly, whereas the other ones protruded a little above the face of the head. They also machined it out and put in
seats. Problem is for checking timing, I really don't want to tear it down far enough to measure the gears. Hoping
just to turn it over and watch valve action compared to piston position and see if any thing is obviously wrong.
slightly, whereas the other ones protruded a little above the face of the head. They also machined it out and put in
seats. Problem is for checking timing, I really don't want to tear it down far enough to measure the gears. Hoping
just to turn it over and watch valve action compared to piston position and see if any thing is obviously wrong.
Lee B
Member
Normally at TDC between exhaust and intake strokes, both valves are still open. But the intake is opening at quite a fast rate and the exhaust is closing just as fast. Called overlap, this region can be extensive measured in degrees. Guesstimate 15 degrees off the top of my head, but this counts from before TDC to past and is the overlap duration itself.
Checking timing with it, I would assume the overlap to be balanced over TDC. Meaning just as much before as after TDC. Quite the job really, best of luck. My take on the rebuild is not to buy another one from that shop -- they don't know what they are doing. Any doubt as to valve size could have been resolved with simple head to head line up - intakes are always bigger than exhaust.
Checking timing with it, I would assume the overlap to be balanced over TDC. Meaning just as much before as after TDC. Quite the job really, best of luck. My take on the rebuild is not to buy another one from that shop -- they don't know what they are doing. Any doubt as to valve size could have been resolved with simple head to head line up - intakes are always bigger than exhaust.
I just don't understand threads like this... for proper operation, it's important that the crank to cam timing be EXACT, even one tooth off will affect power, starting, heating, etc., yet nowhere do I see where you have pulled the timing cover and verified that the factory timing marks are lined up correctly.
Did I miss something here?
With few (if any) exceptions, engines have timing marks and it's not necessary to GUESS or use voodoo "science", or even a degree wheel to get the cam timed correctly in a stock John Deere engine!
That being said, these engines have a unique timing mark setup, and it sure wouldn't be tough for someone to muck it up if they were not aware of that, or didn't bother to consult a shop manual.
Did I miss something here?
With few (if any) exceptions, engines have timing marks and it's not necessary to GUESS or use voodoo "science", or even a degree wheel to get the cam timed correctly in a stock John Deere engine!
That being said, these engines have a unique timing mark setup, and it sure wouldn't be tough for someone to muck it up if they were not aware of that, or didn't bother to consult a shop manual.
Tx Jim
Well-known Member
- Location
- Coyote Flats, Texas
I agree with Bob on importance of checking timing on frt gears.
JD 300 series engines such as 2510 don't have factory timing marks and must be timed with a special tool that is a straight edge with a "V" on one end.
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