Ok, I'm having problems with my '71 Mav (302 w/ stock 2bbl Carb). I'm running a Pertronix Ignitor III w/ HV E-Core (60kV) and everything else stock. I recently replaced the distributor cap, rotor, plugs and plug wires and a tachometer. So here are my problems: 1) My old plug wires were glowing blue at night and my old plugs were looking pretty fouled on the 1-4 cylinder side. I was hoping that it was just the cheap wires. The new wires are good 8mm wires and I just got some Platinum Autolite plugs. I'm still seeing the wires glow blue, especially the lead from the coil. I can see them arching over to the block and the wheelwells, which I'm sure isn't good. At idle, if feels a little bit rough when first warming up, but smooths out when warm. When accelerating, it feels like maybe I'm getting cross-fire or a weak spark or something....it's hard to explain. The power seems decent when accelerating but something isn't quite right. Is there anything like a bad ground or anything like that, that could cause the ignition problem I'm having? I have a voltage gauge to install, but haven't got to install it yet. I will be adding this hopefully this weekend. Would this tell me anything? 2) I had a pretty bad overheat a few months back but the motor survived but now has a light knocking noise when starting until the motor is warm, when it quiets down. Lately I've been having to add water to the radiator on pretty much a daily basis, but never see my temp light come on. I had replaced the thermostat and bought new radiator hose and a new cap, but I'm still losing water. I don't see the motor smoke at all from a head gasket leak. I've seen water come out of the tube by the radiator cap after over-filling with water, but somewhere over the course of my daily 70 mile commute, the water is coming out somewhere. I have a temp gauge to install but not sure where to connect the sensor. 3) I'm having some rough idle after the car warms up. If the RPM is higher than 1000, it seems to be somewhat smooth. I really only see this problem when the car is in "Drive" and sitting still after being warmed up. Normally, in "drive" my car idles at around 700-750 RPM. I have to apply throttle to keep it from wanting to die now. When it is below 1000, the RPM will drop eratically to the point of the motor almost dying. I'm not sure if this is being cause by problems #1 or #2 above or not, but it's got me worried about being stranded on the side of the road. I didn't see this problem before replacing the cap/rotor/plugs/wires/tach. Thanks for all your help! I really need to get this figures out so I don't have to take my other vehicle to work and leave my pregnant wire at home with no ride! Jory
Sounds like you blew a head gasket when you over heated. Here is why I say that. 1) Blue glow and sparks have nothing to do with the head gasket, but feeling a loss of power and poor accleration could be from poor compression between 2 or more cylinders, where the gasket is shot. 2) That knocking noise "could" be air escaping from one cylinder to the other through the hole in the gasket. It sounded like a light ping in one I worked with. Going away when it warms up and gasket partially seals again due to heat expansion??? 3) That water IS going somewhere. Either into the cylinder and evaporating, or possibly into your oil pan. You are running on less than 8 cylinders. Six or less. So you will have erratic idle, poor acceleration, and possible dying engine. I am not saying that you DO have a blown head gasket, but based on your descriptions, i would start looking there. Check your oil...is it milky or gray looking from water being mixed in? Also, there may be oil in the radiator coolant?
Thanks for the reply Scooper! The acceleration is pretty good but more of the sound than the feel, where something seems weird. I've already checked my oil for water and didn't notice anything. The water in my radiator (the original) is/has always been rust colored, even when I'm using coolant with the water. I try to flush it regularly, but it's definitely going somewhere now. I forgot to mention that the lower hose on my radiator looks slightly pinched at the bend going up to the water pump. Could I be getting some pressure build-up at that point causing the radiator to spit water thru the over-flow? I haven't gotten to replace that hose with a better one (used a universal hose, not the custom bent hose...probably why it look kinked). I plan on replacing that too. I know that kink isn't good/right but I'm trying to troubleshoot everything I can. The spark issue is killing me because I can't figure that one out for anything!
I would first address your coolant loss problem. Go to a parts store (or buddies house) and borrow a coolant pressure tester. Check the radiator cap while you are at it. If it is weak, your coolant could be leaking out the overflow while you drive. They also have chemical tests that can check your coolant for combustion gases, indicating a head gasket leak. Do your spark plugs show the burning of water? If your plug wires are shorting to the block/firewall, then you will definitely have a weak (or no) spark at the spark plug. This could cause any or all of your drive-ability problems. What are "good 8mm wires"? I assume you gapped the new plugs?
MercGT73: I don't know anyone with that kind of equipment but there are several parts stores nearby. The radiator cap is brand new because I thought the old one might have been the problem. Could the kink in the lower hose be the problem by not letting water flow correctly and cause pressure to make me lose water thru the overflow hose? The plug wires are MSD Streetfire 8mm wires. They are "good" compared to the bottom-barrel wires I bought at Autozone for around $12 or something. The new plugs are all gapped to .035. Assuming that the plugs are good, the wires are good...what else could cause the wires to be "bleeding" the way they are? Grounding?
The kinked lower hose would cause overheating due to insufficient coolant flow. The water pump cannot create enough pressure to overcome the radiator cap. The pressure required comes from excessive heat (specifically, overheating). I ruled out poor engine grounding because you said the wires short to the block. If they did not short to the block, and only to the firewall, then the engine ground could be suspect.
MercGT73: Ok, thanks for the explanation for the lower hose. That's definitely getting fixed this weekend. For the wire arching, it isn't a strong arch from the wires to the stuff the wires are touching. The strongest arc I'm seeing/feeling is from the lead wire from the coil. If you wet your finger, you can feel it some. The others look more like a small arc anywhere they touch anything under the hood (wheelwells, wires, etc.). The leads from the Pertronix unit going to the coil are glowing slightly too. Not sure if they're getting some arching to them or not. If grounding were the problem, where is the best place to look?
To quickly test for poor grounding, take 1 lead of a set of jumper cables and connect your engine block to the negative battery post. If the arcing stops and your engine smooths out, check your engine ground.
While I'm already recruiting your help, where is the best spot to add the temp gauge sensor? I'm not using the vacuum tree coming off of my thermostat housing...can it go there? Is there somewhere better to put it? What about the oil pressure tubing/coupling? The instructions are very vague and I know a lot of you have already done this. I hope to install this stuff this weekend.
Best bet for the temp sensor is on the intake manifold itself. If your car has a sending unit for an isiot light I would use that spot as with a guage the light isn't really required.
My block has a small terminal with a wire on it in front of the carb, in the center. Is this what you're refering to? Does this just unscrew and you drop in the new temp sensor?
That's not a good place for it. If you put it there you won't be reading the temperature of the engine until the thermostat is open. If the thermostat stuck some day, you wouldn't be getting the engine temp either.
Did you remove the resistor wire when you put the pertronix in? I'm not sure if it will work correctly with less than 12volts.
