No fire

[55312]

OK - I'm running out of ideas. I have a 427 top oiler that has run like a fire hose up until last week. Out of the blue, it won't start. At first I had it flooded and just assumed it was my impatience. After it sat and dried up a bit, it fired up and ran. I drove it down to hose it off and when I went to start it again, it wouldn't. Still convinced it was the fouled plugs, I put new ones in, got it fired up and took it out to hammer the cylinders clean for a short , spirited run. Parked it in the shop and when I went to take it out the next day....no go. I have an MSD 6AL box and MSD Billet distributor. Ran the MSD diagnostics by jumpering the mag pick up and it shoots nice blue fire out of the coil wire from the distributor so I assumed the MSD box and coil were OK. Ohmed out the mag pickup and it came in around 650 - 700 ohms. MSD says 400 to 900 is normal. The kicker is when I pull a plug and crank it over, I get no spark. I've spent all day tracing wires and did find the coil wired backwards with the positive and negative leads from the MSD box reversed and a black "mystery" wire doubled up on the negative pole. MSD said it would still run but don't double up wires on the coil posts. So.....I put the wires on the post where they belonged and took the "mystery" wire and added it to the block ground. Checked the box out again tonight and it passed the test with good blue spark from the coil wire but still no spark to the plugs. I'm stumped...........Anyone have any ideas? I hate swapping parts blind and would like to find a smoking gun. All I can think of is the Mag pickup in the distributor. I have a new cap and rotor coming tomorrow but doubt they are the problem. This engine has been stout and started fine a week ago!

All suggestions are welcome [u]

[xlr8or]

If the lead from the coil to the center of the distributor is firing but the plug wires are not, there are only two things between them. Check the cap and rotor for burn marks or wear. It's possible the contact on the inside of the cap from the coil wire is not contacting the rotor or the rotor tip is bad.

[RICK LAKE]

55312 When I put my car togeather and wired everything up I had the same problem A brand new 6al box. If the ground wire is not on a GOOD ground location or tight you will blow the shunt in the box. The test will pass but the car will not run. I sent mine back to MSD and it was repaired at no charge. What coil are you running? You cann't run any coil on that system. You need the HV one for street. The others will burn up internally. You will get the same problem, good spark on test but car will not run. I have spare 6AL box and distributor module that stay in the car with the tools to change them. I would buy a new box and pickup. replace one part at a time. It will run again and keep these spare parts for the future in the trunk just in case. Rick Lake

[trularin]

I have had several incidents of the rotor burning through and making it appear the ignition was ca-put.

But there have also been a number of threads on running the MSD box. May I recommend a search on this topic after you have replaced the rotor and cap?

Just my $0.02

[55312]

Rick - I'm running an MSD Blaster 2 coil. The mystery to me is that everything has run well up until now. I didn't build this car but have spent the last 4 months finding the warts and cleaning them up. The miswired coil was only the latest thing I've found.

[Tom Wells]

Yo 55312,

My 6AL/Blaster2/MSD distributor combo ran fine for 11,800 miles.

That's how long a Blaster 2 coil lasts when bolted to my intake manifold. My car stopped completely after a few hiccupy episodes.

My coil passed MSD's test. Ohms were OK and it made a spark. It was bad anyway. Replaced it and the problem was totally solved.

Point is, if you can easily swap in a new coil to check this, it may be worthwhile.

Turns out the oil-filled coils don't like heavy, continuous vibration. I have a "Vibration-Proof" MSD Blaster coil in there now. We'll see

If this doesn't work, RICK LAKE has a real good pair of suggestions for the next two substitutions to try.

Let us know how you make out!

[55312]

Thanks Tom.

I have 8,900 on the clock on this one. Will try a new coil. Got a new rotor and cap from MSD today and being brain dead, I forgot the plug wire kit to adapt to a tower cap. Ordered that from Jegs tonight and the new mag pickup will be in Monday. I hate to buy a new box and if it turns out to be that, it'll go back to MSD to be repaired.

Tim

[Rick Parker]

I have a MSD 6T box that has served me well since 1988 (no kidding). Once I was adjusting the idle & timing and it chose that moment to burn through the top of the rotor and begin to ground the secondary into the distributor shaft where the rotor fits over the top of the distributor shaft. I had to look hard & long to find that problem. It wouldn't start after I shut it down.

Those of you that live in humid areas have another issue to contend with too.

Rick

[RICK LAKE]

55312 The coil I am using is the MSD blasterHVC coil # 8252. I was told by MSD tech this is the only one to use for street driving or long periods of cruising. Heat and vibration kill coils. I have never been a fan of mounting a coil on a motor or having it lay on it's side. Oil filled coils need to be in an upright position only. I had a super coil from Accell explode under my hood on my Jeep because of not mounting it up and down. You can go to the Pep boys and get any 12 volt coil to TEST your car. Then bring it back if it works and get the right coil for the application. I would call the horses mouth and ask MSD. Tim ask about a resistor in the system. Some cars need them others do not. Let us know Tim. Rick Lake Ps it's going to be a nice HOT day out. Get it running and go for a drive. Something wonderful is going to happen

[trularin]

Rick, sometimes you can make even the most interesting problems seem okay.