QuestionQUESTION: Hey Dick sorry to bother you, I am trying to fix a problem my cousin started, I have a 1978 Riviera that runs great, or did until earlier today, I have the spark plug firing order but I don't know where to start on the distributor cap! Can you help me? It seems clear to me but the car won't run now so obviously something's off.
Thank you.
ANSWER: This such a common problem that I've developed a sort of canned response to it. Before I add that below, just to make sure, I'll tell you what you already know, the firing order is 1 8 4 3 6 5 7 2.
Now here is what I wrote to the last person with this problem:
Answer: the firing order is 1 8 4 3 6 5 7 2.
Finding out which position on the distributor cap is #1 cylinder is a bit more tricky. Take out the (#1) sparkplug, then place a tuft of Kleenex in the spark plug hole, and using a wrench on the center bolt of the crankshaft, turn the engine clockwise (viewed from the front of the car) slowly until you see the Kleenex puff up out of the hole. (Be careful that you don't suck the Kleenex down into the cylinder on the intake stroke - block the throttle valve open to prevent this.). Now you know you are on the compression stroke on #1 cylinder. Now, slowly bring the piston all the way up to top dead center, still moving clockwise. Watch the timing mark to tell when you are at TDC.
Now the rotor on the distibutor is pointing at the spark plug wire position for #1 cylinder. Plug that wire in, and then the other 7 in the firing order around the cap, making sure that you are going around the cap the right way (by watching which way the rotor turns as you crank the engine clockwise). I hope this is clear enough - if not, ask me again. Dick
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QUESTION: Ok, thanks a lot Dick. So I've got the #1 position based on where the rotor is pointing and then I follow the distributor cap in a clockwise rotation (viewed from front end) plugging the cables in starting with 1 in the #1 position, followed by 8, 4, 3, 6, 5, 7, 2 correct? If this is correct, I still can't get the car to start. I'm baffled because the Riviera started right up and ran very well up until yesterday. I'm giving the car to my mom so that she has a dependable vehicle (because it always has been!)and I was simply giving it a minor tune up and changing the fluids, and after replacing the rotor and cap, the darn thing won't start! My cousin and I had noticed before changing the spark plugs that the firing order that it was currently in was incorrect; may the problem lie there? The firing order it was in was 1 2 7 5 4 3 6 8, which is also baffling, because the car ran very well; it did not sputter or stall out but it also did not have very much power. Dick, do you have any ideas before I have to tow this car to a mechanic?
AnswerThe car would not run with that firing order. I suspect we have a failure to communicate here, and the problem is my fault! The cylinders are numbered 2-4-6-8 down the passenger side, front to back, and 1-3-5-7 down the driver's side, front to back.
The wires go into the cap in the same order as the firing order, starting with #1, in the direction in which the rotor turns as you view it when you crank the engine with the starter (the fan goes clockwise when viewed from the front of the engine). The rotor may turn clockwise, or it may turn counter-clockwise, you have to look at it to see which, and insert the plug wires accordingly.
The piston comes up twice per rotor revolution - you have to do the kleenex trick, or else put a compression gauge in the #1 plug hole to make sure you are on the compression stroke and not the exhaust stroke.
If you picked the wrong cylinder to call #1, say the front one on the passenger's side, you will have to start over to get it running.
You may have used the FORD way of numbering cylinders (1-2-3-4 down the passenger side, and 5-6-7-8 down the driver's side) - if so, that would explain your problems.
All GM, MOPAR and independent brand cars use the cylinder numbering given above - only Ford uses the second system. I'm very sorry that I assumed you would know that - I take full blame for not making it clearer. One of the problems with this service is that I have to make an assumption about how much the person needs in the way of detail. I won't make that mistake again!
Dick
