26 replies to this topic

[booton]

ok doing the timing from scratch on my mini.

people keep saying i could be a 180 deg out.

don;t really know what they mean.

could some one explain. thanks steve

[miniman94]

Hi,
this means that basically the spark plug is trying to ignite when the first cylinder is coming up for the exhaust stroke rather than coming up for the compression stroke. as the crankshaft rotates twice in a full cycle, it is easy to remove the distributor and put it back in with the drive dog180 degrees wrong(although it won't be a pleasant fit that way round). this would mean that the rotor arm will be aligned with the 3rd cylinder rather than the first which it should be. The easiest fix in this scenario is to remove the distributor drive shaft from the block and flip it 180, although when re-inserting it remember that it will turn slightly due to the angle of the teeth.

[Cooperman]

When the ignition timing is set, cylinders no 1 & 4 need to be both at top dead centre at the same time. If, in fact, the cam has both valves closed on no.1 that is the cylinder which should be sparking. However, if the spark is at no.4 at this point, the timing is 180 degrees out.
To check this, take the rocker cover off, bring pistons 1 & 4 to TDC and see which rockers have clearance. i.e., you can get a feeler gauge under both inlet and exhaust. Now, without moving the engine, remove the distributor cap and see where the rotor arm is pointing. The contact in the cap towards which the rotor arm is pointing should have its ignition lead connected to the plug which is fitted to the firing cylinder (that's after you re-fit the plugs of course). Then, working round the cap anti-clockwise as you look at it, the plug lead order is 1-3-4-2, so, if for exampole, you just fitted no.4 lead because no.4 was at the firing point, the next lead round ant-clock will be 2, then1 rhen 3.

[booton]

ok good.

on a different note. because the crank shaft turns two times to one of the cam shaft, when doing the cam timing from scratch, does it matter which turn the crank is on for it to be dot to dot.

i assume that the turn of the crank shaft doesn't change. but i just wanted to check this. that it doesn't matter which cycle its on. ( if this makes sense.)

[booton]

thanks for your help makes more sense now. will have a play tomz.

[Cooperman]

No it doesn't matter. When you line up the cam sprocket and the crank sprocket dot-to-dot, and the chain is then fitted, the cam is timed correctly. When doing this pistons 1 & 4 are at TDC anyway.

[booton]

good good i thought this what people was on about when they said they said it could be 180 deg out.

so, this makes it easier. lol

thank goodness for this site. don't know where i would be

[Cooperman]

With the cam fitted and timed and the timing chain on, bring 1 & 4 to TDC, then put push rods into the push rod holes for 1 & 4 inlet and exhaust valves. Push down on all push rods whilst turning the crankshaft a bit both ways. You will feel two of the push rods don't move but on the other cylinder there will be some vertical movement of the push rods. The ones which don't move are those of the cylinder which is in firing position. If this is not no.1 rotate the crank 360 degrees so that it is. Once it is firing on number 1, make sure the distributor drive is correctly position as shown in the Haqynes or Rover workshop manual. Then the dizzy will time in easily.

[jaydee]

Sorry but i really dont get how you would have fitted the camshaft 180° out.
People who are you listening to are probably referring to the DIZZY driveshaft.

[Cooperman]

Sorry but i really dont get how you would have fitted the camshaft 180° out.
People who are you listening to are probably referring to the DIZZY driveshaft.

I assumed he meant the ignition timing at 180 degs out. After all, if you time dot-to-dot and the dots are in line with 1 & 4 at TDC the cam is timed correctly.
It is not absoultely vital to get the dizzy drive shaft in the correct position so long as you connect the ignition leads to the correct cap locations for that position and the dizzy will actually fit having regard to the vac adv/ret fitting having clearance to go in and turn a bit to get the timing accurate.
If you did dot-to-dot and the dot on the cam sprocket was diagonally opposite the dot on the crank sprocket it would be possible to be 180 out, but surely no-one would do that, would they................??

[jaydee]

Exactly, and with the standard gears theres no room for such an operator error..
I wouldnt be surprised if his problem is fuelling related instead.

[mrbridger]

I lined them up like this with a 'modified' straight edge steel rule with cylinders 1 and 4 at TDC and it was fine.

[booton]

 23092011941.jpg   587.15K   9 downloads
i've done the exact same thing.

the only problem is i have a veneer timing kit so its adjustable.

so i could be out a little because of the adjustment that can be made,

hopefully it should start from this, will put piston 1 to tdc (with the dots joining) i believe from reading that there should be clearance between both valves on cylinder one. to see it the timing is done right.

correct me if i'm wrong.

[Cooperman]

 23092011941.jpg   587.15K   9 downloads
i've done the exact same thing.

the only problem is i have a veneer timing kit so its adjustable.

so i could be out a little because of the adjustment that can be made,

hopefully it should start from this, will put piston 1 to tdc (with the dots joining) i believe from reading that there should be clearance between both valves on cylinder one. to see it the timing is done right.

correct me if i'm wrong.

The valves with clearance on both could be 1 or 4, but it doesn't matter so long as the plug leads go to the right plugs.

[jaydee]

What crank gear is that? is that fitted the other way round? If i recall correctly I've seen only with dots at the front and not with that mark..
And measure lift at overlap, you must have equal lift when the camshaft is poperly dialled in.

Edited by jaydee, 27 September 2011 - 05:45 PM.