John Deere 330 timing issue / puzzled ...

I have been rebuilding a 330 engine the last month. Long story but had this block machined .45 over , magnifluxed, dipped, etc. same goes for the head dipped, checked for leaks, new valves, seats, s
springs,and guides, spared no expense or shortcuts on this nice tractor. The engine ehen I got it had spun a rod and had two teeth broken on the governor. So with that I got another camshaft gear with same part number and installed on the old cam this was inspected and ok. When I reassembled the bottom. End I put both the crank and camshaft gear in time( so I thought ) with the little dots the size on a pencil head online together. Had. H dad confirm I wasn't crazy or wrong. Then the finish assembly was done exactly as factory Deere repair manaual said. Ben had a speciality tool for timing the oil pump with the distributor . I followed the correct instructions and the short side of slot facing out with the flat side of tool facing out to ensure it was in time. I have the clave cover off at this time and from here on. Set the valve lash at .12 by book which seemed tight to me. Then checked for spark and fixed a few loose connections then got fire. Off to fuel put fuel in and verified the bowl was fuel. The proceeded to turn ending over on choke with nothing. Pulled plug to see no fuel on it. So I out my hand on intake breather only to have compression blowing out instead of suction.....! Puzzled by this I thought maybe a valve was sticking . Nope.. Then I thought maybe they weren't seating properly. With inspection camera it they looked ok.. Puzzled again... So I tried a,compression test and both cylinders show 25psi!!!! How could that be with new Pistons, rings, and new bore .45 over. Rings were staggered properly and cylinders oiled down. So I looked at the flywheel and verified TDC on number one and it shows to be correct. I am really puzzled here cause I know the cam gear only goes one way and I never took the crank gear off. I did out another cam gear on camshaft but it had same part number off an mt tractor. My does however use a diff cam which I quickly saw. I did however see what looked like somebody had hit or dropped the cam gear and left a ding on same side as timing mark. I thought it looked funny and not factory . Also by the size of dent not matching the crankshaft one I quickly Matched it up with other mark.. Looked like one in book. Something is wrong here but I'm not sure what to do next . I'm afraid the camshaft is somehow out of time but how!?? Anybody had this problem with blowing back intake and no fuel in combustion chamber.
 
It sounds like you are onto it, blowing back has to be a valve timing or leaking issue.

I would suspect cam if both cylinders are low.
 
Yes I'm afraid unless somebody knows another procedure, I will have to tear all the way down to the cam and figure out why the timing marks are not correct. The bad part is if they are lined up which was verified . I'm gonna have a hard time figuring out what tooth will be correct...
 
If you pull valve cover off and can verify tdc you can get pretty close in checking valve timing.

Both valves will be closed at tdc on power stroke . the exhaust valve will start to open a little before bdc. maybe 20 degrees or so . the exhaust valve will close at or close to tdc at the end of the exhaust stroke. the intake valve will start to open at tdc or maybe a degree or two after . the numbers are not exact , but most tractor cams have little to no overlap and operate close to this example. the intake timing is more critical than exhaust. and if I was to ever( my waterloo boy ) set cam timing with no tools or marks I would try to get intake to open right at tdc .
 
My guess is that when installing the oil pump you did not have number one cylinder up on DC compression stroke. You can have the the DC indexed mark on the flywheel showing in the timing hole but still be 180 degrees out of time. When installing the oil pump the engine must be on TDC compression stroke. Take out #1 spark plug. Put your finger over the plug hole and rotate the crankshaft clockwise until you feel pressure on your finger. Continue to turn the crank and look in the timing hole for the "DC" mark on the flywheel to appear in the hole and align it with the indexed mark at the timing hole. Now you are at TDC compression and you can install the oil pump. I would do this before ripping into anything else. All that you need to do is drop the pan. Hope this helps.
 
I used the original camshaft that came out of the tractor and had the machine shop check it. The cam gear itself I replaced with another one
same part number because it had two teeth broke off from an older governor failure.... My thinking it maybe the crankshaft gear key has
possibly sheared and even though I set the time marks on both gears maybe the gear has moved on crankshaft ??? I don't believe it's 180
degrees out because I'm getting compression back through the intake not allowing a suction to I'll gas through . It won't even let me spray
staring fluid I to carb without pushing it out ... Has anyone found more than one timing mark on cam gear???
 
How did you spin a rod, spare no expense and not have that crank turned since the gear wasn't removed? Spinning a bearing alway's damages both contact surfaces. Your camshaft and gear are both the same as an M, MT, 40. 420/430's are different camshaft's with the same gear. Don't know for sure how but your timing is off. Here's how to verify from the tech manual.
a225320.jpg
 
I bought it not running with spun rod. Yes I had everything turned rods and mains . Yes the cam gear is same part # but came is diff part numbers from what I removed from 330 and what was in MT tractor I got new can hear from. There were some serial number breaks middle 330 production and i know the crank, Rods, and maybe can were all changed in the 330s in gonna pull apart front cover today to look at timing marks again...
 
Rather than put all faith in part number matching and just leave it there you should have put both cam gears side by side and gave them the close up once over back when it was much easier to do. I suspect it's a defective cam gear machining wise and you will see easily that the key isn't in the same place as the old one if the timing marks are both at noon O'clock for example. Other than a spun crank gear which is highly unlikely, I see no other way you can have these symptoms which of course are classic 45-90 or so degrees way off cam timing issues. When you've see one like it, you can't forget it because it's just screaming the issue at you if only you understood the language. You've done everything else quite well in my opinion, putting all your faith in part number method is about to be revised. Mechanic's life lesson star date 23,741.25 - watch out for this guy named Murphy. Note to self, pull the crank gear just to have a look see, the price is right.
 
Glad to hear the crank was turned. It's been too long and I can't remember if the crank gear is a one way only installation. Either it's off or one of the marks is. You can use that chart to verify or even install a gear with no mark.

Cam part number is AM3631T - sub-M11T, M3908T, AM681T. Gear is M49T with one sub- AM678T. The parts book shows no cam change during production of the 330.

The same part numbers show up in every parts catalog I mentioned so they are all interchangeable. You can download all the parts manuals free from jdparts.com.
 
Got the old girl running again!!! Some idiot got the bright idea to stamp his own timing marks on the cam gear instead of paying attention to the original then I guess he realized there was one then he double stamped the right one which made it look wrong to me in comparison to the correct mark.... Lessen learned people do stupid things and just following the service book don't always mean it will run.. I should have held up the original broken gear to compare marks . Lol
 
No offence but you're talking about ignition timing which has absolutely no effect on valve timing which is where he is losing the compression.
 
So many times on these Forums guys post about missing timing marks. I've been through a wide variety of various engines over many years and can't remember EVER not being able to find the factory marks.

Of course there ARE certain engines out there that ARE unmarked and a special tool/jig is needed.
 

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