Half my engine is not firing... I'm stumped

I'm very puzzled...
I'm tring to sooth out the final details on my engine swap (5.0 from 95 mustang) and just hit a brick wall. It seemed to me that the engine was missing so I stared to investigate by taking the ignition wires off the distributor one by one. Removing wires 3, 2, 5, 8 made no difference in how it runs. 1, 7, 6, 4 changed the idle and I, therefore, concluded that they are working. With 3, 2, 5, 8 all removed the engine runs just the same as it did when I started. As of now I'm only running on four cylinders (1,4,6,7). These happen to be every other wire on the distributor whitch leads me to believe that it is no coincidence.
What Ive tried: I tested the ends of all the wires and they all spark (but mabe not at the right time??). Tried the old 302/289 firing order but was much worse. I reset the distributor making sure that #1 is at tdc and rotor pointing to #1 wire. Reset timing to 12 degrees before tdc. I quadruple checked that all the wires are in the correct place and that the firing order is right (1-3-7-2-6-5-4-8)
Details that might matter: Spark plugs are all new (autolites) and new wires. original ford electronic ignition. Accel distributor that I bought on ebay "lighly used." I was told that the springs were changed inside the dist. to alter the curve (I can't think why this would matter).
I really hope that someone out there can think of someting...
Thanks, Dan

 

Put the original Duraspark Distributor in there to see if it runs ... don't run it too long because it'll grind down the cast dizzy gear pretty quick ...

 

that sounds like a good idea. I still have the original Duraspark Distributor but no longer have the cap or wires that fit (i now have the hei style). I threw out alot or old "junk" 2 weeks ago that I thought I would never need again... bad move . I'll see if I can somehow get a hold of some... Thanks

ps this is a pic of the distributor I now have

 

I have thought long and hard on this one. I believe since so far this is an all Dan thread it can be figured out. Dan HInes idea of trying another distributor is really the only way to troubleshoot the one you are trying to use. Keep us posted.
Dan

 

Would a 5.0 even be able to run on 4 cylinders? I don't think so ..perhaps it really isn't missing on every other one. You running a stock coil with the aftermarket dizzy and aftermarket wires? What spark plug gap you running? I know the Duraspark II calls for gapping at .050 ... not sure if that changes with with the differenty dizzy and wires.

BTW .. I just did the same swap a month ago ... 1995 5.0 engine ... using a Pertronix Billet distributor, Accel Coil, Edelbrock Carb & intake ... gapped my Motorcraft plugs at .038 ... Runs great ....

 

Are you running a dual plane intake? If you are it sounds like a main jet or an idle feed is stopped up on one side of the carb.

 

My 302 ran on 4 cylinders once. Sounded good, too. Kinda "lopey".

I had a miss on 3 cylinders, killing 2 and 50% leak on 3rd (later found a bunch of bent valves). I pulled the two dead plugs, no difference. The pulled the 3rd, ran a little rough. Then plug #4, nice and lopey. I think it stalled when I pulled the 5th, don't remember.

At the time, I was more interested in which cylinders were dead, and why.

By the way, what are the differences between the 302 and the 5.0? Would I be better off buying a junkyard 5.0 and working it up, or pulling out my running 302 (w/55k miles) and rebuilding it? What benefits would I get?

 

Biggest difference is a Hydraulic Roller Camshaft! And going with a late model 5.0 is way way cheaper than retrofitting an early engine to a roller cam ...

 

I have the plugs gapped at .050. A 5.0 will run on only 4 cylinders, actually pretty well, considering. right now my 2,3,5,8 wires are not connected to the distributor and it fires right up and runs ok. (but I really want to turn this v4 into a v8 ). The coil is the one that came with the 5.0 but I have been planning to buy an msd blaster.

RegL404, I'd like to hear more on the dual plane idea. I have the dual plane edelbrock air gap and a new holley 4bbl carb. Is it possible that ONLY the two outter cylinders (1,4) on the passenger side and the two inner cylinders (6,7) on the driver side would work if one side of the carb is not working? Is that how dual plane is designed?

 

So you are saying that 2-3-5-8 wires are actually firing but maybe not at the correct time, if so what type of rocker arms are on the engine, are they adjustable? If they are the kind that you tighten down all the way then was any of the valve train worked on or modified? It sounds like the valves may be opened up on those cylinders or it could be 180 degrees out of time also.

 

The late model is a little lighter, and the crank is a little weaker.

As for the missing, actually on topic, ya got me...

 

The valve train was worked. I had to change the head gaskets so I took off all the rockers and pushrods. they are the factory stamped rockers. I tightened them all back down to the torque in the manual. Could I have done someting wrong that is causing all this?
(Tested the "180 degrees out of time" idea. It didn't really run, just some backfires).

 

That is exactly how the dual plane works. The 2 outer cylinders on one bank are paired with the 2 inner ones on the opposite bank....so if the carb only works on the left or right side, it will run on 4 cylinders more or less. Years ago, I ran a RPM manifold on a 302 with a Edelbrock carb on a race car (electric fuel pump). We'd put the car up for a couple weeks and shut off the fuel pump and run it until it'd die. Just before it died, it would run on 4 cylinders...and the way that it ran, it sounded like an old VW beetle.

cyls 3,2,5,8 all run off of the right side of the carb, 1,7,6,4 run off of the left side of the carb.

Might be onto something there....

 

Yeah, scratch my ealier post......the carb being dead on one side sounds logical to me, I didn't know what cylinders were paired together then. That's what I love about this board, there is bound to be an answer to your problems sooner or later. :bananaman