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is this the problem?? |
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CC 79 
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Joined: October-19-2004 Location: United Kingdom Status: Offline Points: 19 |
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 Topic: is this the problem??Posted: November-03-2004 at 8:23pm |
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I need to ascertain which plug leads go where from the distributor cap to the plugs. Here is how my 79 nauti Ford 351 is wired: i.e the no1 piston is directly behind driver seat,(closest to raw water pump)
1 2 3 4 5 6 7 8 The lead from no1 piston goes to cap point directly above the rear cap screw clip,( looking from above) and the order is 18456273 going counter clockwise round cap ( again from above) Is all this right??? It is nearly midnight here in UK or else i would phone shop and ask, but i have only just thought that this may be my problem. Help!!! |
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jameski
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Joined: May-18-2004 Location: United States Status: Offline Points: 368 |
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Posted: November-03-2004 at 9:45pm |
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Yes, That is the correct firing order.
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79nautique
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Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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Posted: November-04-2004 at 11:19am |
This may or maynot be the starting point on the dist cap. The best way to find out where your no.1 lead starts is to remove the no.1 spark plug, bump the starter until you here air coming out of the cylinder. Basicly you are finding the TDC of piston no.1. Now remove the dist cap and the tower that the tip of the rotor is pointing to is where the no.1 spark plug lead goes, then go clockwise for the remaining leads according to the firing order. |
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66polyhead
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Posted: November-04-2004 at 3:10pm |
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Also remember, No. 1 cylinder has an exhaust stroke, and a compression stroke, the plug fires on compression and not exhaust!
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Tim D
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Posted: November-04-2004 at 4:03pm |
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TDC is when both rocker arms are in the down position. With the valve cover off you really know TDC.
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Tim D
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CC 79
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Posted: November-04-2004 at 5:10pm |
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79nautique, you said:
then go clockwise for the remaining leads according to the firing order. Did you mean counter clockwise? |
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captan1
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Posted: November-17-2004 at 5:16pm |
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I've researched this a little and I think I remember that the firing order is reverse like mentioned from CC79 and the cam is turning reverse also by way of the timing chain, but the cam gear is ground opposite of a car which makes the driven distributor gear spin the normal direction making the rotor spin the same direction as a car motor, just firing in a different order. So whatever direction the auto book says is correct, and same for the reverse rotation 351. That's why Comp Cams have special cam cores to grind whatever spec's you want for reverse rotation engines.
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79nautique
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Posted: November-19-2004 at 11:47am |
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The distributor rotates in the same direction for reverse and standard rotation PCM engines.
66polyhead and tim D you are both correct but you forgot onething, when it is on the exhaust stroke the exhaust valve is open until the piston reaches the top of it's stroke then the valve closes before the down stroke. With this in mind you will not have air expelled out of the spark plug opening or there will be very little and you can tell the differnce between the compression stroke verse the exhaust stroke. Also another check is to look at the timing mark on the compression stroke the mark will be lined up on the exhaust stroke it will not be lined up. |
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Keith
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Posted: November-19-2004 at 1:39pm |
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Hey 79Nautique, It is easy to tell the difference between compression and exhaust. During compression, both valves are closed. An easy way to do this without the valve cover off is to put your thumb in the spark plug hole and have someone bump the starter until air is forced past your thumb. This is the compression stroke.
The timing mark on the balancer will line up on both exhaust and compression strokes. Obviously the piston is at TDC once for every crankshaft rotation. This means that the timing mark will line up every time the piston is at TDC. Also, both valves will not be closed between the exhaust and intake stroke. The intake valve opens before the exhaust valve shuts. This helps get the intake charge in early and to force out the remaining exhaust. The only time both valves will be shut at TDC is during the compression stroks. |
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captan1
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Posted: November-19-2004 at 2:06pm |
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I agree, no matter what stroke you're on the timing mark connected to the pulley connected to the crank and on 0 degrees that piston better be at the top of intake or exhaust or you have bigger problems. If you take off the valve cover over no. 1 cylinder to watch the intake valve open then close knowing the next time 0 degrees is on the timing pointer you are at TDC on the compression stroke and no matter where you start the no.1 firing order on the distributor cap (can be anywhere on the cap the rotor is pointing to) you will be in the right place.
In the old day's I would find TDC on no.1 cylinder, pull the distributor and rotate the housing to where ever I wanted to look best or to route the wire like I wanted and then drop it back in and it didn't matter where it slipped in, I just start the firing order on the cap at 1 where the rotor pointed, makes no difference as lone as no. 1 is TDC on compression stroke, and you start the firing order from there. I love ignition stuff, you can gain HP if it is right on including your advance curve or you can be sluggish with lousy response if it's not enough or coming in to late. |
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79nautique
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Posted: November-19-2004 at 3:16pm |
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Yes I agree that it is pretty easy to find TDC for the no. 1 cylinder and that you can orient the dist about anywhere as long as it is at TDC for the no. 1 cyl when you install dist.
It just seemed to me that others where trying to imply that you could not tell the diferent between the exhaust stroke and the compression stroke when the spark plug was removed. And that you had to remove the valve cover to know wheather it was on the exhaust or compression stroke. Also the timing mark will only line up on the compression stroke and not the exhaust stroke. |
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captan1
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Posted: November-19-2004 at 3:40pm |
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OK, so... piston at TDC compression, timing mark on 0, plug fires and piston goes down, piston comes up ( exhaust stroke )and piston at TDC 0 on the timing mark then piston goes down on the intake stroke and comes up on the compression stroke to 0 on the timing mark and fires the plug. Two TDC's and four strokes of the piston, down up down up. Right?
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Keith
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Posted: November-19-2004 at 3:53pm |
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79Nautique, you don't know what you're talking about on the timing mark. Captan1 is correct. Timing mark lines up every time the piston comes up.
You may be confused with the rotor. It will only line up with the No. 1 spark plug wire on the compression stroke. On the exhaust stroke, the rotor will be pointed 180 degrees away from the No. 1 spark plug. BTW, the crankshaft makes two revolutions every time the camshaft (which turns the distributor) makes one revolution. But the timing mark on the balancer, which is attached to the crankshaft, lines up with the mark on both the compression and exhaust stroke. Keith |
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new86owner
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Posted: November-19-2004 at 4:01pm |
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Here are some additional links to help anyone out who is confused.
http://auto.howstuffworks.com/engine4.htm http://auto.howstuffworks.com/engine11.htm |
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CC 79 wrote: