| tex42 | -- 04-21-2013 @ 2:51 PM |
|
I'm in the process of restoring a 42 Tudor that's was my wife's father's car. I had the engine rebuilt several years ago ( had a 46 Merc in it). Boarded .60 over with Offenhouser 2 Duce manifold and Edelbrock Aliminum heads, and Protronix ignition. Started the engine up and in checking for the reason for a miss, I found that #3. & 7 cylinders are not firing. Checked fire to plugs and even changed these two plugs and they are getting fire. I have 120 lbs at all cylinders. I pulled the intake and checked the valve setting and all were close to specs. I even connected tube to plug holes of 3 & 7 and I can not blow into each when the exhaust valve and the intake valve is closed. Anyone have any thought why I do not have fire to these two cylinders? David
|
|
| carcrazy | -- 04-21-2013 @ 3:44 PM |
|
This sounds like a really perplexing problem. Are you sure you have fire to spark plugs numbers 3 and 7? What kind of ignition wires are you using? Are you sure you have continuity from the terminal in the distributor cap to the spark plug in each case? Could the wires to cylinders no. 3 and 7 be in the wrong locations in the distributor cap? Are you running the wires through metal conduits that could allow the wires to cross-fire to another cylinder? Assuming everything is correct mechanically and you have fuel/air mixture going to the problem cylinders, the problem has to be one of no or too little voltage to the plugs.
|
|
| supereal | -- 04-21-2013 @ 3:57 PM |
|
I 'd suspect the non stock ignition. Over the years, we have removed several of them for problems like yours. As cylinders 3 and 7 are on opposite sides of the block, the ignition is the only common link. These aftermarket ignition systems get cranky (no pun) when they sit for a long time. Unless you are racing, a stock ignition is perfectly adequate.
|
|
| deuce_roadster | -- 04-21-2013 @ 4:28 PM |
|
Listen to Super. If you still have the 42 distributor, have it rebuilt with good points and condenser and put it on. That is what I run on my 32 and it is VERY reliable, in fact for many, the 42 "crab" distributor is the one of choice.
|
|
| tex42 | -- 04-21-2013 @ 7:01 PM |
|
I've already converted it to 12V Neg ground. I also have an Protronix high voltage coil. I've also removed the resistor to the coil. Will the original Distributor run off of 12 V? Do I now need a new coil? I'm sure I have to replace the resistor in the ignition. Anything else? David
|
|
| supereal | -- 04-21-2013 @ 9:21 PM |
|
I'm not familiar with Protronics ignition, but the ones we have worked on of other brands have a variety of elements to control the function of contact points in the original type. They can be a reluctor wheel, Allen effect, or other kinds. As you are getting spark in six of eight cylinders, it appears the coil is operating, but the distribution of spark is at fault. When capacity discharge systems were popular, we saw plenty of that. They were subject to loss of the critical gap of the trigger. In many cases that produced erratic ignition. Others were temperature and/or temperature sensitive. With old Fords, they are a solution in search of a problem.
|
|
| tex42 | -- 04-22-2013 @ 4:22 AM |
|
I'm getting spark to all 8 cylenders.
|
|
| supereal | -- 04-22-2013 @ 5:55 AM |
|
You said that in your original post, but the question is, as I understand it, is that the cylinders you mention are not actually firing, causing a pronounced miss, even though you detect spark at those plugs. With good compression, a strong spark is required for actual firing. That is why, without actually seeing your car, that the distribution and strength of the ignition appears to be the obvious cause. The only other possibility would be a timing problem, unlikely as the other six cylinders are OK.
|
|
| EFV-8 Club Forum : | https://www.earlyfordv8.org/forum |
| Topic: | https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=5953 |