Cylinder and Firing order question.

L

Los

Low Mileage
Quick question.

When standing at the back of the car from left to right what is the Cylinder order and the Firing order respectively?

When establishing timing which Cylinder should be at the top of its stroke at TDC?

These are elementary questions that are probably written in a manual I don't own yet...... but I like a challenge. :hmm:

Glenn
 
Quick answer

Cylinders are numbered 1-4 from the front of the motor (right side of the car).

So from left to right it's 4-3-2-1.

Firing order is 1-3-4-2.

Early cars are timed from cylinder #1. IIRC, later cars are timed from #4. So we'd need to know the year of your car for that one.

But that does bring up an ancillary question: what year did ignition timing start being taken from #4? Assuming my memory isn't playing tricks on me....

HTH,

///Mike
 
Well.... just how old are ya ///Mike?

I'm really old but I still time ALL cars offa #1 from a ELECTRICAL standpoint.

I believe the CAM timing )on all X's) is where we set the CRANK at TDC, then align the timing mark for the CAM on its mark, and then the ROTOR should be pointing at #4.

I've thought really hard about this over the years and still don't really get it. #1 and #4 are exactly opposite of each other (1-3-4-2) and I'm unsure WHY it makes a difference, or IF it really makes a difference, from an ELECTRICAL standpoint, but it sure appears to make a difference from a MECHANICAL standpoint.
 
Well...

...I knew #4 was involved somehow. At least I could get credit for that.

Am watching Transporter 3 and I have a serious thang for redheads. I'm lucky I can remember my name.

///Somebody
 
#1 and #4 are both at TDC at the same time...

once for every revolution of the crankshaft, but because the camshaft turns at half the speed of the crankshaft, the camshaft can be in either of two positions - either the cam pulley mark is lined up, or it is halfway around.

At TDC, one of these cylinders will have both valves open for the end of the exhaust stroke and start of the intake stroke. The other will have both valves closed, the compression stroke just finished and the power stroke starting. This is the one that you want the dizzy to fire (actually, to have just fired, because you probably want a few degrees of advance). Turn the crankshaft another full turn from there, and the camshaft will go a half turn, and the two pistons will come back around to TDC but with the valves the other way around.

The way the stock camshaft and pulley on the 1300 works, when you've lined up all the timing marks it is #4 cylinder that should fire.

I have a '79 1500 engine that needs #1 cylinder to fire when all the timing marks are aligned. I have no idea whether that's standard 1500 behavior or whether I have a weird cam and/or cam pulley.

When you're using a timing light to set the timing, you can use either #1 or #4 to trigger the strobe. You only get a flash every other rotation of the crankshaft anyways, and the crankshaft is in the same position when #4 and #1 fire.
 
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You can time from #1 or #4, makes no difference

Here's why - as with most I4 motors, the 1 and 4 pistons are in lock step (as are the 2 and 3). So when the 1 is up, so is the 4 (and when 1 and 4 are TDC, 2 and 3 are BDC). The only exception to this involves a bent crankshaft.

Now when timing an engine, the only part of the top end that is involved is a plug wire. You attach a probe to a wire (1 or 4) and when the motor fires that cylinder, the timing light fires and you see the freeze-frame of the flywheel position. However, since it's a 4-stroke-cycle engine, the flash only occurs every other engine rotation (the flash does not occur when the piston is near TDC on the exhaust stroke).

So if you numbered the engine rotations from 1 to x, and timed off the #1 wire, you would see the flashes for the odd rotations (1, 3, 5, etc). If you timed it off the #4 wire, you would see the flashes for the even rotations (2, 4, 6, etc).

Bottom line is, it makes no difference whatsoever. The manual may have changed at some point which wire it stated, but the end result is identical.

Clear as mud? :)

Pete
 
Clear as mud?

Well, clearer than my explanation :)

There is one last pitfall out there: The Haynes book and many other sources (including at least my copy of the '74 shop manual) tell you to set the distributor to fire #1 cylinder when the timing marks are aligned.

But it's #4 for the 1300s. I thought it was #4 always, but it's not for the only 1500 I've owned. Because it's the only one, I don't know whether mine is an anomaly or the 1500s are all that way. In any case, it's just a matter of where on the cam pulley the mark is.
 
Cool movie!!!
With great car action :woot:
Love the part where he 'enters' the train :shock2:
/Paul
 
Good points (no pun intended)

Those points are very valid for assembling an engine and preparing it for firing.

My comments assumed an assembled and running engine.

Pete
 
///Mike said:
But that does bring up an ancillary question: what year did ignition timing start being taken from #4? Assuming my memory isn't playing tricks on me....

HTH,

///Mike
Click to expand...

As far as my experience goes, and it goes back to mid 1950's Fiat products, then. I have not had earlier engines apart, but out of habit I would time them on 4. Unless it had more or less cylinders!
 
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