302 firing order - Ford Mustang Forum
 
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post #1 of 13 (permalink) Old 09-01-2013 Thread Starter
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302 firing order

Greetings,
I have a 302 engine and all i know about it is that it is a 302. I know that there are two different firing orders,one for the 302 and another for the 302 HO. Right now I have it set with the 302 HO firing order and the car runs but it is a bit rough. My questions are: will the engine run if I switch to the other firing order? Will the engine be rougher with the other firing order and how do I know which firing order to use? I thank you in advance for your help.
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post #2 of 13 (permalink) Old 09-01-2013
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If it's an early 302, it needs to be set to that firing order, assuming it doesn't have a 5.0 cam in it.
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post #3 of 13 (permalink) Old 09-01-2013
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here is a video with both the firing orders in it. interesting how the HO set up eliminated the infamous number 3 rod knock.

https://www.youtube.com/watch?v=3I-_iEFCPOI

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post #4 of 13 (permalink) Old 09-01-2013
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302 H.O. and 351 Windsor small block- 1,3,7,2,6,5,4,8
All other ford V-8's- 1,5,4,2,6,3,7,8
The only difference in an H.O. 302 and a non H.O. 302 internally is the camshaft. Just use the correct firing order for the cam you have. They will interchange. Just remember That ALL '85 and up H.O. cams are roller cams. '84 H.O. and most other 302 cams are not.
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post #5 of 13 (permalink) Old 09-02-2013 Thread Starter
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Greetings,
Thank you all for responding to my question. I looked at the video and it is very good. Does any one know how I can tell if I have the car set up with the wrong firing order for the 302? Someone told me that if I had the firing order wrong the car will not run. Others say that it will run but not very well. Please let me know how I could tell if I have the firing order correct. Thanks.
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post #6 of 13 (permalink) Old 09-02-2013
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I'd start by putting the timing on TDC and check if the #1 piston is in the up position. Then pop the distributor cap and see if the rotor is pointing to the #1 spark plug wire on the distributor cap. If it is, then check your firing order going in a counter clockwise position from spark plug wire #1. Depending on what cam you have, will determine your firing order. In otherwords, say your firing order is 15426378. The next wire going in a counterclockwise position should be #5 cylinder. #1,2,3,4 are on the passenger side of the block, 5678 on the driver's side in that order. Then the next wire should go to #4 and so forth. If #1 does not line up with the distributor rotor, you'll have to pull the distributor and reinstall in the proper position. MAKE SURE THE PISTON IS AT THE TOP OF CYLINDER #1 and the timing mark is on TDC.
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post #7 of 13 (permalink) Old 09-03-2013 Thread Starter
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Thanks for the information. Perhaps I might be confusing everyone on this issue. My question is: the car is running on one of the two firing orders now but it is a bit rough. Can I change the firing order to the other one and run the car and if so what should I look for in the way of better/worse performance? If I have guessed on the wrong firing order will the car even start and if so will it run much worse if it is the wrong firing order? Any help will be much appreciated. Thanks.
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post #8 of 13 (permalink) Old 09-03-2013
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The firing order is completely different between the two. One should not even start the car. You probably have the correct firing order, but the whole sequence could be off by one. That is why I said to check if the #1 wire is pointing to the rotor at TDC. That will tell you if the distributor is in correctly. Otherwise, I'd check your ignition wires to see if they are broken or have a bad connection, etc. Sometimes, ignition wires can have a break and will shorten causing a serious misfire.
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post #9 of 13 (permalink) Old 09-04-2013 Thread Starter
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Thanks for the quick reply. That is what I thought would happen if I had the wrong firing order. The wires are new but there still could be an issue with them. I will do as you recommended and check the diet for proper alignment with #1. If everything lines up perhaps there might be an issue with one of the cylinders. I will reply with what I fine. Again thanks.
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I just went through this on a 289 rebuild using a new cam. The guy who had the cam said that it was the newer firing order so that is the way I wired it. The engine started, ran, but had no power. The engine would quickly die as soon as the clutch was engaged. I changed to the 15426378 order and problem was solved. Car ran fine. Interesting thing, the idle was pretty much the same regardless of which firing order was used.
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post #11 of 13 (permalink) Old 09-06-2013 Thread Starter
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Tinhorse,
I hope to get time next week to try the TDC/rotor position as well as your suggestion. I will reply with results as soon as I get them. Thanks.
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302 firing order

Hello killerzap,

I would like to offer a whole new approach to this issue.
In my opinion - -this has been going on TOO long.
My suggestion MAY cost you $20.00 BUT it will tell you a LOT.

I mean no disrespect to the GREAT ideas you have been given
BUt this is what I think you should do and you will KNOW what cam is
in there.

So here we go
Remove the valve covers. You MAY have to get a set of valve cover gaskets
BUT yours MAY be OK. Depends if they are CORK or rubber and if the Previous owner
used silicone

So with the valve covers OFF you can see the rocker arms. They sit on the
valve stems.
I am going to try to explain this in simple terms in case you or others and not
that familiar with the make-up of heads.

Each cylinder has 2 valves. One is for intake and the other is for exhaust.

The rocker arm - -that is above the exhaust PORT is of course the exhaust valve
meaning the other valve is the intake valve.
To be sure you understand - - - Look at the driver side FIRST CYLINDER.
That cylinder is #5 - - now look at the exhaust manifold - -see where it attaches to the head? - -just above that will be the exhaust VALVE and ROCKER.

Have an assistant sit in the car - - BEFORE they do anything - -PULL the COIL wire.
That is the wire that is in the CENTER of the distributor cap. With the coil wire removed the motor WILL NOT start.

Now - - have the assistant - -turn the key to the start position for about 1 second.
The motor will crank.

What you want to do is WATCH for when the #1 INTAKE "rocker" starts to go down. GREAT - - -now have the assistant - -"tap the key again and see what is the
NEXT INTAKE rocker that starts to go down.

It will either be #3 OR #5.

Then look at the firing orders imlowr2 posted for you.

I HOPE this makes sense. You watch the #1 intake open - - -then watch to see if the #3 or #5 intake moves downward next.

Once you know this you can then at least know for CERTAIN te firing order.

Once you know the FO - -then you can do as others suggest and take #1 to TDC on compression stroke and see if the rotor is close.

I think the FIRST thing you need to do is determine the correct Firing ORder

then we can help fine tune.

Let us know if you do any of these things and we will help more

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post #13 of 13 (permalink) Old 09-15-2013 Thread Starter
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Print Dad and all the others, thanks so much for the input. What I have done so far is to test both firing orders and on one order the car will start but runs very rough and backfires, on the other firing order it starts and runs smoothly. I did not drive the car during this test, I just let it idle for fear of doing damage. The firing order that works is: 1,3,2,6,5,4,8,1. I want to see where the rotor is pointing to when cylinder 1 is in the compression phase and at TDC. That is next on the list. I hope to get to that shortly. Being unemployed everyone at home thinks I have all the time in the world so I am doing more things for them than if I actually had a job. Again, thanks for the help and I will report as soon as I can.
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