msd7al-3 problem
 

kind of a weird deal.supergas car-msd7al-3 on car.35 degrees total timing with flying crank trigger. all msd parts.at idle car has 35 degrees total timing,as soon as you rev it up it drops 10 degrees timing! tried 3 dif timing lights-2 different boxes-changed all the chips-changed crank trigger sensor.msd says it can't do that . took dist out and checked gear and camshaft-all perfect.it idles at 1200 rpm,as soon as it gets to 1500 rpm it drops 10 degrees instantly,we raced the car by setting the timing at 45 degrees and as soon as it goes up it drops to 35 degrees.went 3 rounds that way.but it ain't right! also run a shielded crank sensor wire. have been told to look at all the grounds on car.this car is 2 years old and nothing has been moved or changed. thought maybe somebody out there has seen this before.low profile billet dist for crank sensor setup.

Re: msd7al-3 problem
 

Check timing belt/gear/chain first---as you rev up the engine the stretch tends to retard the timing---next any MSD system needs to be wired this way or gremlins can present themselves


all Wiring MUST BE STRANDED wiring at least #12 preferably #10

at the least #4 starter wire--prefer #2 or #0 same for ground



ground heads to block

ground block to frame

ground MSD directly to the battery

Re: msd7al-3 problem
 

jesel belt drive.new and only has 45 runs on it.ground goes to engine block at bellhousing. steel block-aluminum heads.heads are not grounded.

Re: msd7al-3 problem
 

Ground heads to block !!!! anyway--- Belt defective and stretching??? check with Jesel ??? bet they can give you an answer--FED 387

Re: msd7al-3 problem
 

reverse green and violet wires from the crank trigger to the box at the box see what happens to your timing....mine did the same as yours reversed the wires ,,fixed!

Re: msd7al-3 problem
 

I agree about the polarity of the crank trigger wires. I've seen it and fixed it before.
Dan

Re: msd7al-3 problem
 

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

Re: msd7al-3 problem
 

YEP, had a freind 2 weeks ago was about to load up after trying everything he had, motor just didn't sound right either. So I asked him what have you done...he said nothing just pulled this chip out cause I didn't need it, he put it in FIXED. Those units require a chip in each position always.

Re: msd7al-3 problem
 

I have 0 retard chips in each retard slot.even took them out and put 4 more new ones in!

Re: msd7al-3 problem
 

All 4 retard inputs must also be grounded besides having the zero pill in if the retard is not being used.
I'd check that ground .

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.

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!

Re: msd7al-3 problem
 

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.

Re: msd7al-3 problem
 

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.

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.

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"

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

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

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.

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.

Re: msd7al-3 problem
 

Anyone ever find out what is causing this ??

Re: msd7al-3 problem
 

I figured it out what was causing the timing to retard of idle.the crank trigger wheel was installed backwards ! that reversed polarity and caused the problem. reversed the M+ & M- wires and that fixed it but I wanted to know why? kep looking and figured it out.looked in a old MSD trouble shooting book and it had a whole page on asking and telling you to make sure the wheel is on correctly.