Got towed home yesterday need engine help - Page 2

Silverstreak02 · #21 (**permalink**) 06-28-2012, 07:26 PM

I finally got a chance to work on the Cobra tonight. It's definitely an ignition problem and I believe the distributor may be the culprit. I'd like to run this by everyone to get opinions.

I hooked my inline spark tester into the #1 spark plug and motored the engine. The light in the tester would light one time as soon as the engine started to turn over and then nothing. I tried this several times with similar results except for once the light came on several times and the engine tried to start. As soon as the light went out the engine stalled. I moved the tester to another spark plug and had similar results.

I checked for power and ground being supplied to the distributor with a test light and the light came on. I tried to get power at the output of the distributor to the coil, but I didn't get any. I think the distributor has to be spinning for this power, but I'm not sure. I moved my spark tester to the coil wire and disconnected the power and ground wire for the coil from the distributor. I ran a hot (12vdc) wire directly to the hot side of the coil and touched the ground wire to ground. Each time I touched ground the light in the tester came on. Since this was consistent I believe it means the coil is working correctly when it has a known power supply. I reconnected the power lead from the coil to the distributor and tried starting the engine again. As the engine was turning over I grounded the coil ground wire to the block. Sometimes the light would come on and other times it wouldn't. As expected the engine tried to start if I got several sparks in a row.

I believe this proves it is an ignition problem and the coil seems to be working correctly. That gets me down to the distributor not supplying power to the coil on a reliable basis. I plan to call Mallory tomorrow and ask if they can test and repair my Max-fire, but want to ask you guys if my troubleshooting and conclusion is correct. Is there anything else I can try? Am I out to lunch? Thanks for any comments.

Jeff

mln385 · #22 (**permalink**) 06-29-2012, 05:22 AM

Sounds like a bad pickup module in the dizzy.

mln385 · #23 (**permalink**) 06-29-2012, 05:37 AM

Try this link it may help. Century Performance Center, Inc. :: Mallory MBI Module Testing

HighPlainsDrifter · #24 (**permalink**) 06-29-2012, 10:59 AM

Hi,
1st- Do you have a resistor in the positive lead to the distributor, should be mallory 700. If you do not have the resistor you will burn out your coil.
Replace coil and add the resistor in the power line.
good luck,
Perry.

Silverstreak02 · #25 (**permalink**) 06-29-2012, 06:00 PM

I called and talked to Mallory today. I explained all the symptoms and my troubleshooting procedure. At the end of my long story he said something like this is hard to diagnose over the phone, but said it sounded like the coil was working correctly and something was going on with the distributor. He recommended sending in the coil and distributor for testing. I downloaded the online repair form and will remove the components for testing this weekend. I'll put them in the mail on Monday. He said the testing will take between 2 to 3 weeks and then someone will call me with the results and repair options. It looks like I'm going to have some time to catch up on my honey do's

Jeff

Silverstreak02 · #26 (**permalink**) 06-29-2012, 06:07 PM

Quote:

Originally Posted by HighPlainsDrifter

Hi,
1st- Do you have a resistor in the positive lead to the distributor, should be mallory 700. If you do not have the resistor you will burn out your coil.
Replace coil and add the resistor in the power line.
good luck,
Perry.

Perry

The wiring directions for the Maxfire said there should not be any ballast resistors or loom resistance wire in the red power wire going to the distributor. It also said to make sure the red wire supplies 12vdc in the start and run position. I guess the Maxfire is different than some of the others. I don't have a resistor and have confirmed the 12vdc.

Jeff

Silverstreak02 · #27 (**permalink**) 07-26-2012, 12:10 PM

Mallory called today after testing the coil and distributor. They said the coil was fine, but they found a loose condenser on the printed circuit board of the distributor. They replaced the circuit board and tested it with my coil for 1 1/2 hours at different rpm's and it worked fine. They shipped it this morning so I should get it early next week. Believe it or not they did the work for free. Pretty amazing considering they have a 90 day warranty and these parts were bought more than 2 years ago. I'm very happy with their support and look forward to hearing the Cobra fire up again.

I asked if they were seeing very many of the Maxfires come in for repair. My thought was maybe it's not a great idea to have electronic stuff inside the distributor. She said they don't see any more of them than any of the other distributors they make. I guess that's good news. She said I could exchange it for a different model for an additional $120 if I wanted to go back to the old style mechanical advance. I'm going to stay with what I have.

Jeff

CowtownCobra · #28 (**permalink**) 07-26-2012, 01:38 PM

Good to hear, I've used Mallory for years with good results. Glad they fixed the problem (and are still in business!)

Dirty Harry · #29 (**permalink**) 07-26-2012, 07:52 PM

Your local parts store will sell you a spark tester for under $10 and you don't have to just lay the plug on the engine and hope it's grounded.

Silverstreak02 · #30 (**permalink**) 07-31-2012, 07:34 PM

I got my distributor and coil back from Mallory tonight. I was happy since I haven't driven the car since fathers day. When I unpacked it I discovered my alignment marks were gone on the shaft, but I sort of expected that. When I took the cap off to set the rev limiter and timing curve I discovered the cap and rotor were brand new. I thought replacing the cap and rotor was nice, but unnecessary since they only had 1800 miles on them. I got my settings right, put a little assembly lube in the gear and tried to install it in the engine. It wouldn't go in more than a few inchess. It stopped as soon as the fat part of the shaft started to go into the hole. I looked at it closely and it looked like the shaft of the distributor was larger than the hole. I figured I was doing something wrong so I tried again with the same results. I gave up and brought out the calipers. The shaft measured 1.555 and the hole was 1.485. So the numbers tell the story. The distributor shaft is .070 larger than the hole in the engine. When I talked to Mallory last week it sounded like they had repaired mine and was sending it back, but I'm not sure where this one came from. They also sent a clear plastic bag that has the software, all the wiring and cover. I think maybe they sent me a new distributor. Of course that doesn't explain why it doesn't fit. I'm bummed out.

Jeff

HighPlainsDrifter · #31 (**permalink**) 07-31-2012, 09:12 PM

Hi,
Sounds like they sent you a 351 dist instead of a 302. Is the 6 sided hex oil pump shaft hole on the bottom 1/4"= 302 or 5/16"=351.
Good luck,
Perry.

Silverstreak02 · #32 (**permalink**) 08-01-2012, 05:51 PM

Quote:

Originally Posted by HighPlainsDrifter

Hi,
Sounds like they sent you a 351 dist instead of a 302. Is the 6 sided hex oil pump shaft hole on the bottom 1/4"= 302 or 5/16"=351.
Good luck,
Perry.

It is 1/4" and according to the part number it is for a 302. See my next post for more information.

Jeff

Silverstreak02 · #33 (**permalink**) 08-01-2012, 05:54 PM

I called and spoke to the women that repaired my distributor. As soon as I told her the shaft was too large for the hole she knew what was wrong. She said there are two sizes of shafts that look exactly the same, but one is larger than the other. She said she must have installed the wrong one. She apologized over and over and offered to make it right. It was nice that she admitted to the mistake and apologized for it. I printed out another repair form and will ship it back tomorrow. It looks like it'll be a couple more weeks before I hear the engine come to life again.

Jeff

Silverstreak02 · #34 (**permalink**) 08-12-2012, 01:02 PM

The distributor arrived earlier than expected on Friday. I installed it last night and finished the details this morning. I really wanted to use my new piston stop to find TDC since my damper isn't marked. Unfortunately the piston stop won't thread into the cylinder. It looks like the right diameter and is the right thread pitch, but it won't fit. Anyway I'll have to figure out the timing later. Now to the good part. I rolled the car out into the driveway added a little bit of gas to the carburetor and it started on the first crank. The sound of that motor was music to my ears. It went up on the high idle and ran very smooth. Smoother than before to be honest. I kicked it down after it was up to temp and it went into a nice 650rpm idle. I shut it off to put the air cleaner on and it started instantly without touching the gas. While I have no way of knowing for sure I think the timing must be pretty close. I'll work on that more later, but for now I'm a happy camper.