Timing issue

J

Jeff Fischer

Daily Driver
Hi Guys

I changed the timing belt on my 77 X1/9 yesterday but forgot to put the cam and drive shaft at TDC. I did put the car in gear before replacing the belt. I am sure that the cam and drive shaft did not turn while changing the belt. I can’t say the same for the gear that turns the distributor, it turned a bit but after putting in where I thought it was but the car did not fire. I did get it to fire and start a bit but the car was running rough by putting the cam and drive shaft to TDC and then put the distributor aligned on number 1. I moved the distributor far to the right ( toward the firewall) but again it ran rough and did conk out. Have I screwed up the valves or is it just a case that I need to get the distributor set properly in relation to where the cam and drive shaft are positioned

Thx Jeff
 
Jeff,
Timing at the belt is at TDC but ignition timing is at 5 BTDC on carb engines (10 BTDC on fi). When you are at 5 BTDC, lift the distributor and move the rotor until it point to the position in the cap for the #4 piston (transmission side). Put back the distributor cap and bolt the distributor in place. You should be close to the right timing. A little turn of the cap (by loosening the nut) on one side or the other should get you the optimum.
 
Jeff Fischer said:
I am sure that the cam and drive shaft did not turn while changing the belt.
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If you are absolutely morally certain that you did not move the cam or crankshaft while the belt was off, then the pistons and valves will still be in the right positions relative to one another and nothing will have been damaged; it’s all about getting the spark to happen at the right time.

So turn the motor until the crank and cam marks are lined up at TDC (crank timing mark at the 0 TDC mark, cam mark lined up with the finger on the snail mount) and set the distributor to fire #4 cylinder as @Daniel Forest says above. (Remember that the crank turns twice for every turn of the cam, so if the cam looks to be out by a half turn, give the crank another full turn to bring the cam around).

If you cannot get the marks to line up, you have in fact lost the timing relationship between cam and crank and you’ll need to restore it and then check for valve damage.
 
For another crank timing reference, there are timing marks (0, 5, & 10 degrees) on the "view port" of the bell housing and a "dot" on the flywheel. The "dot" can be hard to find on an "in service" flywheel that has some patina, but look for it when you think you have the marks lined up on the timing belt end of the engine. The flywheel mark is just another check that can make you feel good about your set up. (Or bad I guess, but let's think good for now)
IM002985.JPG
 
You said you put the distributor "aligned at no. 1". The rotor has to be pointing to the number 4 plug wire port, not the number 1 wire port.
 
Hi Guys

I will try what I have read, if the cam and drive shaft are all aligned properly what should be the position of the lobs on the cam in relation to cylinder 1. Should The cam lob be pushing the valve down or off the valve?.

Thx Jeff
 
Jeff Fischer said:
Hi Guys

I will try what I have read, if the cam and drive shaft are all aligned properly what should be the position of the lobs on the cam in relation to cylinder 1. Should The cam lob be pushing the valve down or off the valve?.

Thx Jeff
Click to expand...

1 and 4 will have all valves in the up position and the cams will be not be engaging those valves.
 
Easy way to tell is to remove spark plug at piston #1 and insert a long rod to ensure the piston is at TDC. If you are unsure about the results, turn the crank a complete rotation and check again. You should notice a difference between both test. So now you will know which one is TDC and you can move the cam Wheel to the right position.
 
Jeff Fischer said:
Hi Guys

I will try what I have read, if the cam and drive shaft are all aligned properly what should be the position of the lobs on the cam in relation to cylinder 1. Should The cam lob be pushing the valve down or off the valve?.

Thx Jeff
Click to expand...
With all the timing marks lined up....

Pistons 1 and 4 will both be at TDC because they go up and down together (as do 2 and 3, but they’re down when 1 and 4 are up and vice versa).

The valves for #4 cylinder will be closed (top of the compression stroke, ready to fire) so the lobes will be pointing up equally, sort of like the letter V.

The valves for #1 cylinder will be partly open (overlap at the top of the exhaust stroke and start of the intake stroke) so the lobes will be pointing down equally, sort of like an upside-down letter V. As the cam continues to turn the intake lobe will push its valve farther down while the exhaust lobe will move off the exhaust valve to allow it to close completely.
 
Daniel Forest said:
Easy way to tell is to remove spark plug at piston #1 and insert a long rod to ensure the piston is at TDC. If you are unsure about the results, turn the crank a complete rotation and check again.
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A full rotation just brings the pistons back where they were before, no?
 
EricH said:
A full rotation just brings the pistons back where they were before, no?
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I was Under the impression it took 2 rotations to bring the pistons back where they were. But I guess the bottom part is doing a full rotation while the cam is doing just 1/2...:oops:
 
It is one full rotation to bring things back to where they were, the cam takes two revolutions to get back to where it was as it runs at half speed. The cam and ignition is what makes the difference as to what is actually going on.

The difference is that when the crank does its one turn, the cam does its half turn and as a result the valves are now and have been in different positions relative to the pistons. In the one case cylinder one is in compression, four in exhaust, three is in the power stroke and two is in intake. Alternating through the firing order and the four strokes of an Otto engine process.
 
Just an update guys

I can’t get the car started with all the suggestions from this post. My next step is to remove the head from the car and see what damage has been done. Can anybody suggest where I can get the head work done or should I just buy one from MW. Any comments on replacing valves on a 1300 head, can it be done by me or should I get a pro to do it. What things should I look for when taking it apart

Thx Jeff

Thx for your
 
before you go pulling the head, a simple check for valve bend is to check the lash clearances... bent valves = excessive lash clearance (usually)

if it ran (albeit chugging a bit) then it's probably just timing / spark ...

SteveC
 
Take advantage of modern tools, like an inspection camera that you can feed into the cylinders to look at the valve faces, to see if they are all seating. You can come to the valve from the other direction, too, but of course it's not as easy, requiring removal of the carb/FI plenum for the intakes and the downpipe for the exhausts. Looking in the hole, most (but not all) of the time, contact hard enough to bend a valve will leave a mark on the piston.

Or go old school tool with a leakdown tester, which pressurizes the cylinder. Given your circumstances, if you can't get a hole to hold air regardless of camshaft position, then likely there is a valve stuck open from contact.
 
You should also check compression before going whole hog.

I would go back and verify your setup one more time, the static engine timing and then carefully run through the ignition timing.

As this is a points car, one way to get very close to correct ignition timing right out of the gate is after getting the mechanical timing of the engine mechanical parts correct, set the crank pulley at 5 or 10°BTDC depending on what you want. Then take a 12v led or standard light bulb with the ground lead to the points post on the distributor and the positive to the hot side of the distributor. Verify that #4 is approaching TDC with the valves closed, turn the ignition to ‘On’ the light more than likely will be on. Then loosen the distributor clamp and rotate it until the light turns off. You will be effectively properly timed. Tighten the clamp and give her a go.
 
Jeff Fischer said:
My next step is to remove the head from the car and see what damage has been done.
Click to expand...
Don't pull the head yet. First thing to do is to turn the motor until the crank timing mark is lined up and see where the cam mark is (and if the cam mark looks about 1/2 turn off, turn the crank over one more turn to line things up). If the cam mark is a little bit off, chances are that the motor was just mistimed before you started in on it and nothing is broken.

If you can't get your cam timing mark to line up, take the belt off, move the cam until it does line up, replace and retension the belt (Don't force the cam pulley if it doesn't want to turn, but seeing as how you've already run the engine, any valve-piston smash has already happened so turning the motor over by hand isn't going to make anything worse). Then try starting it again, with the distributor set to fire #4 when everything is lined up.

If it still runs like crap and you can't get it right by playing with the timing.... Check compression, and like @fiatfactory says above, check your valve clearances. If the valve clearances are not suddenly way way too high and the compression is reasonable, you haven't broken anything.

Report the results of these tests before you go pulling the head. also consider the possibility that it's running badly because you have some crud caught in the carburetor's idle circuit and that's misleading you.

But in any case..... DO NOT pull the head until all other possibilities have been excluded.
 
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Hi Guys

Thanks for this, I will try these ideas this week. I am a bit miffed off on the whole car thing right now and want to cool down for a couple of days. I will get back to the post and let you know what I find.

Thx Jeff
 
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