msd7al-3 problem - Page 2

flash · 09-26-2015, 11:45 PM

I just checked my wiring of the car.none of the 4 retards are grounded. wired car by K & R wiring diagram and it does not show that either.easy enough to do but how does this get missed? talked to MSD twice and they never mentioned it either.will try thay tomorrow.

flash · 09-27-2015, 07:50 PM

thanks for all the advice! just thought everybody would want a followup on what was the problem and what fixed it.I tried grounding all 4 retard terminals and that did not change anything.I reversed the 2 wires from crank trigger-greem & purple wires that go to -M & +M to reverse the polarity and "that fixed it" timing is dead on 35 degrees. but the question is this-what happened or caused this to happen? wired the car 2 years ago with a K & R wiring kit.and we have checked and changed timing several times and it was always right.then one day the car slows down and we start checking things and found this problem.will it happen again and have to switch them back? happy to have found the problem and fixed it so easy. thanks to everybody that chimed in with advice!

Bobby Fazio · 09-28-2015, 10:20 AM

Quote:

Originally Posted by GaryGoFast

I think that box has to have "0" degree retard chips when no retard being used.

I had the same problem. Take these chips out and do a OHM test with a multimeter. They should have 0.00 ohms. Regardless, if not using high speed timing control, throw these chips away altogether and ground the Timing #1, #2, #3, #4 terminals on the side of the box. Daisy chain three of the them and then run to a good ground. I had this same problem.

buzzinhalfdozen · 09-28-2015, 03:45 PM

Quote:

Originally Posted by flash

thanks for all the advice! just thought everybody would want a followup on what was the problem and what fixed it.I tried grounding all 4 retard terminals and that did not change anything.I reversed the 2 wires from crank trigger-greem & purple wires that go to -M & +M to reverse the polarity and "that fixed it" timing is dead on 35 degrees. but the question is this-what happened or caused this to happen? wired the car 2 years ago with a K & R wiring kit.and we have checked and changed timing several times and it was always right.then one day the car slows down and we start checking things and found this problem.will it happen again and have to switch them back? happy to have found the problem and fixed it so easy. thanks to everybody that chimed in with advice!

Replace the crank sensor, switching polarity is not normal and would think it a sign the sensor has issues. Just change it and throw the old one in the tool box as an emergency spare, just be sure to tag it as to the issue you were having.

Mike Pearson · 09-28-2015, 05:15 PM

I would also replace the sensor. My car slowed down and I thought something was wrong internally in the engine. I freshened up the engine and found nothing wrong internally. When I went to start the engine after the freshen up the engine would not start. I replaced the sensor and it started.

flash · 10-10-2015, 04:35 PM

Found the problem,crank trigger wheel was mounted backwards.that reverses polarity,which is why reversing the crank trigger wires fixed the issue. took the crank trigger wheel off and reversed it,changed wires back to correct way and it works rock solid with timing light. note- the crank trigger wheel does have a register and a small arrow pointing the direction it should rotate,but it will mount either way.I guess it was that way since we had motor out last time and just never noticed the timing moving if you brought the motor up off idle. Feel like a "dummy"

buzzinhalfdozen · 10-12-2015, 03:30 PM

Flash, I'm glad you found a problem, however I doubt that will be the long term fix as the magnets will not change polarity (ie North or South pole) due to being turned in an opposite direction. I'd still consider putting a new pick up on as it's been documented many times that they can actually change polarity. I'm not exactly sure how or why they do it but I've seen it quite a few times. Perhaps we have an electical engineer on here that may be able to shed some lite on that subject. All this of course is moot if you're not running the "flying magnet" wheel. Good luck Joe

flash · 10-12-2015, 07:23 PM

I purchased a new sensor,changed it ,and still had the problem-that's when we read a 2002 msd troubleshooting manuel and it had a full section on being sure you did not have the wheel backwards.thats when we discovered the wheel was backwards because we could see the direction arrow on the back side with a mirror and was pointing the wrong way. we reversed the wheel,put the wires "-M & +M " the correct way and it worked. really not happy with MSD tech as we talked to them 3 separate times about this and all the said was that's not possible! I got better info on classracer.com

buzzinhalfdozen · 10-14-2015, 03:10 PM

Flash, glad to here that, though the reasoning behind it eludes me. Thanks for the follow up sure to help someone else with a similar issue.

OhioMafiaWireGuy · 12-23-2015, 10:54 AM

This is becoming problem we see more and more. When a car comes into our shop, that I cant start for any reason, I tape a note to the switch panel reminding the owner they have to check the timing and then reverse the polarity and check it again.

MSD has even published an Appendix stating the same. The rule of thumb is this: Check the timing and then reverse the wires and check it again. For Analog ignition boxes you want the mag pick up wiring that gives you the most retard. For Digital boxes you want the most advance. Leave the polarity that yields one of those for that given type of box.

On a dyno, I have seen this be worth 96 Hp on my personal motor.

In regards to the 7AL3's... ensure the box is grounded directly to the battery! Ensure all the 0 chips are installed! AND...ground the unused step retards.

09-26-2015, 11:45 PM	#11
flash Junior Member Join Date: Apr 2012 Posts: 89 Likes: 1 Liked 6 Times in 5 Posts	Re: msd7al-3 problem I just checked my wiring of the car.none of the 4 retards are grounded. wired car by K & R wiring diagram and it does not show that either.easy enough to do but how does this get missed? talked to MSD twice and they never mentioned it either.will try thay tomorrow.

09-27-2015, 07:50 PM	#12
flash Junior Member Join Date: Apr 2012 Posts: 89 Likes: 1 Liked 6 Times in 5 Posts	Re: msd7al-3 problem thanks for all the advice! just thought everybody would want a followup on what was the problem and what fixed it.I tried grounding all 4 retard terminals and that did not change anything.I reversed the 2 wires from crank trigger-greem & purple wires that go to -M & +M to reverse the polarity and "that fixed it" timing is dead on 35 degrees. but the question is this-what happened or caused this to happen? wired the car 2 years ago with a K & R wiring kit.and we have checked and changed timing several times and it was always right.then one day the car slows down and we start checking things and found this problem.will it happen again and have to switch them back? happy to have found the problem and fixed it so easy. thanks to everybody that chimed in with advice!

09-28-2015, 05:15 PM	#15
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,318 Likes: 546 Liked 1,629 Times in 502 Posts	Re: msd7al-3 problem I would also replace the sensor. My car slowed down and I thought something was wrong internally in the engine. I freshened up the engine and found nothing wrong internally. When I went to start the engine after the freshen up the engine would not start. I replaced the sensor and it started. __________________ Mike Pearson 2485 SS

10-10-2015, 04:35 PM	#16
flash Junior Member Join Date: Apr 2012 Posts: 89 Likes: 1 Liked 6 Times in 5 Posts	Re: msd7al-3 problem Found the problem,crank trigger wheel was mounted backwards.that reverses polarity,which is why reversing the crank trigger wires fixed the issue. took the crank trigger wheel off and reversed it,changed wires back to correct way and it works rock solid with timing light. note- the crank trigger wheel does have a register and a small arrow pointing the direction it should rotate,but it will mount either way.I guess it was that way since we had motor out last time and just never noticed the timing moving if you brought the motor up off idle. Feel like a "dummy"

10-12-2015, 03:30 PM	#17
buzzinhalfdozen Senior Member Join Date: Sep 2006 Location: Bellevue Ohio Posts: 985 Likes: 0 Liked 12 Times in 9 Posts	Re: msd7al-3 problem Flash, I'm glad you found a problem, however I doubt that will be the long term fix as the magnets will not change polarity (ie North or South pole) due to being turned in an opposite direction. I'd still consider putting a new pick up on as it's been documented many times that they can actually change polarity. I'm not exactly sure how or why they do it but I've seen it quite a few times. Perhaps we have an electical engineer on here that may be able to shed some lite on that subject. All this of course is moot if you're not running the "flying magnet" wheel. Good luck Joe __________________ Joe Buchanan SS/BX 3117

10-12-2015, 07:23 PM	#18
flash Junior Member Join Date: Apr 2012 Posts: 89 Likes: 1 Liked 6 Times in 5 Posts	Re: msd7al-3 problem I purchased a new sensor,changed it ,and still had the problem-that's when we read a 2002 msd troubleshooting manuel and it had a full section on being sure you did not have the wheel backwards.thats when we discovered the wheel was backwards because we could see the direction arrow on the back side with a mirror and was pointing the wrong way. we reversed the wheel,put the wires "-M & +M " the correct way and it worked. really not happy with MSD tech as we talked to them 3 separate times about this and all the said was that's not possible! I got better info on classracer.com

10-14-2015, 03:10 PM	#19
buzzinhalfdozen Senior Member Join Date: Sep 2006 Location: Bellevue Ohio Posts: 985 Likes: 0 Liked 12 Times in 9 Posts	Re: msd7al-3 problem Flash, glad to here that, though the reasoning behind it eludes me. Thanks for the follow up sure to help someone else with a similar issue. __________________ Joe Buchanan SS/BX 3117

12-23-2015, 10:54 AM	#20
OhioMafiaWireGuy Junior Member Join Date: Dec 2015 Posts: 1 Likes: 0 Liked 0 Times in 0 Posts	Re: msd7al-3 problem This is becoming problem we see more and more. When a car comes into our shop, that I cant start for any reason, I tape a note to the switch panel reminding the owner they have to check the timing and then reverse the polarity and check it again. MSD has even published an Appendix stating the same. The rule of thumb is this: Check the timing and then reverse the wires and check it again. For Analog ignition boxes you want the mag pick up wiring that gives you the most retard. For Digital boxes you want the most advance. Leave the polarity that yields one of those for that given type of box. On a dyno, I have seen this be worth 96 Hp on my personal motor. In regards to the 7AL3's... ensure the box is grounded directly to the battery! Ensure all the 0 chips are installed! AND...ground the unused step retards.