Crank Trigger issue

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Crank Trigger issue

Post  maverick532 on January 11th 2015, 9:28 pm

I have an issue with my msd crank trigger , maybe someone can shed some light on . Have watched a video on set up , read instructions several times , reconfirmed tdc , checked wiring and set up of ignition box ( msd 7al3 ) checked to make sure arrow on crank trigger is facing out , set it up for 32 degrees of timing and when fired up shows 6 degrees , am using msd timing light , have checked phasing of distributor , spot on . distributor is msd and advance is locked out as it should be , aggravating me to no end , since distributor still has mag pickup in it , I disconnected crank trigger and plugged in the distributor , fired up , timing checked out at 32 degrees engine idles properly and sounds great . Anyone have a problem like this ?
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Re: Crank Trigger issue

Post  rmcomprandy on January 11th 2015, 9:56 pm

maverick532 wrote:I have an issue with my msd crank trigger , maybe someone can shed some light on . Have watched a video on set up , read instructions several times , reconfirmed tdc , checked wiring and set up of ignition box ( msd 7al3 ) checked to make sure arrow on crank trigger is facing out , set it up for 32 degrees of timing and when fired up shows 6 degrees , am using msd timing light , have checked phasing of distributor , spot on . distributor is msd and advance is locked out as it should be , aggravating me to no end , since distributor still has mag pickup in it , I disconnected crank trigger and plugged in the distributor , fired up , timing checked out at 32 degrees engine idles properly and sounds great . Anyone have a problem like this ?

Something is not right.
Sounds like the distributor has the pick-up wires reversed.

(They should be phased in the most retarded position; there WILL be a difference).

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Re: Crank Trigger issue

Post  maverick on January 12th 2015, 7:05 pm

rmcomprandy wrote:
maverick532 wrote:I have an issue with my msd crank trigger , maybe someone can shed some light on . Have watched a video on set up , read instructions several times , reconfirmed tdc , checked wiring and set up of ignition box ( msd 7al3 ) checked to make sure arrow on crank trigger is facing out , set it up for 32 degrees of timing and when fired up shows 6 degrees , am using msd timing light , have checked phasing of distributor , spot on . distributor is msd and advance is locked out as it should be , aggravating me to no end , since distributor still has mag pickup in it , I disconnected crank trigger and plugged in the distributor , fired up , timing checked out at 32 degrees engine idles properly and sounds great . Anyone have a problem like this ?

Something is not right.
Sounds like the distributor has the pick-up wires reversed.

(They should be phased in the most retarded position; there WILL be a difference).


Yup.  Pay close attention to rotor phase with a 7al3.  It has an automatic start retard which can cause grief if phasing allowances are not made to accomodate the retard.  It's in the instructions...if you don't have 'em, download 'em.

The older 7al3 (like mine) retards the spark by 24* until the engine starts and revs ABOVE 1400 rpms.   If you're firing it up and letting it idle, you won't see the timing come back in.  Try taking the revs up to a couple thousand and checking again.
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Re: Crank Trigger issue

Post  maverick on January 12th 2015, 7:44 pm

One other note: A 7al3 with a crank trigger will show 4* less timing when running than you will see when timing at the balancer with the engine off. As an example, you'll probably need to set at 36* on the balancer to see 32* when running. Also in the instructions.

Don't treat the 7al3 like all other MSD's. DAHIK. Suspect
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Re: Crank Trigger issue

Post  c.evans on January 12th 2015, 8:09 pm

What Maverick said is correct, and also let me mention that you can defeat that cranking retard that's in the MSD box by clipping the gray wire.

Also what Randy said is correct and IMO most likely your problem. The MSD tech manual explains this as your polarity and most likely you have your mag+ reversed with your mag-. The black wire with the purple tracer is reversed with the black wire with the green tracer. Swap them around at the box. It will move the timing a bunch!

Charlie

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Re: Crank Trigger issue

Post  Lem Evans on January 12th 2015, 8:46 pm

c.evans wrote:What Maverick said is correct, and also let me mention that you can defeat that cranking retard that's in the MSD box by clipping the gray wire.

Also what Randy said is correct and IMO most likely your problem.  The MSD tech manual explains this as your polarity and most likely you have your mag+ reversed with your mag-.  The black wire with the purple tracer is reversed with the black wire with the green tracer.  Swap them around at the box.  It will move the timing a bunch!

Charlie

I could not agree more....the start retard function in the 7AL-3 box is 'retarded'.....lol!

I.m.o. the 7AL-2 Plus box is a better friend.

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crank trigger problems

Post  maverick532 on January 12th 2015, 9:14 pm

thank you all for your help , I looked it over again tonight and still don't know what the problem was . I ran the engine yesterday on the distributor and set timing at 32 degrees at idle speed 1500 rpm , I then hooked up the start retard function of the 7al3 to be in play only when engine is cranking over , I checked polarity as suggested , I had it wired right , all parts are new msd . I checked the set up again all is good , plugged the crank trigger in crossed my fingers hit the switch she fired right up , let her warm up a little checked timing , shows 30 degrees idling at 1500 . I'm happy it's working now it's time to get the rest of the car back together so I can go test . Again thank you all . Paul .
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Re: Crank Trigger issue

Post  the Coug on January 12th 2015, 9:18 pm

I prefer the 7al2 been dependable heard to many horror stories about the 7al3s
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Re: Crank Trigger issue

Post  hienergy557 on January 12th 2015, 9:32 pm

http://www.innovatorswest.com/964-Crank-Trigger-Sensor.html

Read the notes on the above link.
I did have to swap mine around. (7AL-2 with a start retard box & innovators sensor)
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Re: Crank Trigger issue

Post  Curt on January 13th 2015, 12:52 pm

It's easy to remember, using an analog system is retarded and using a digital system in more advanced.
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Re: Crank Trigger issue

Post  BigDave65 on January 14th 2015, 10:07 am

What balancer are you using. Sometimes with an ATI you have to buy a different hub to get it indexed properly!

FWIW, I've used a 7AL3 since 1998, with a crank trigger and the start retard, without a single issue. There is times I've blamed the box but it was always something else.
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