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Erratic timing MSD 6-al

Posted: Sun Jun 14, 2009 7:46 pm
by fat bastard
Has anyone seen this?

I am running a 6-al box, billet distributor, locked out timing set at 34 degrees, When ever I throttle up, soft ot hard, it reaches a certain point and engine starts to break up, timing setting bounces down to 10 degrees and back to 34, when it is at 34 degrees engine runs fine. Then it is like a switch is flicked and back to 10, starts stumbling missing etc.

I swapped in a new pick up, still there, could it be the box? or something else.

Checked dist gear, ok. I disconnected the two step and the rev limiter. Still there.

I appreciate all answers.

One racer told me he fixed the same situation rejetting carb, I don't think so, what relation would that have in the timing jumping? This is a fresh motor, about a 40 runs on it, timing chain and gears new.

Re: Erratic timing MSD 6-al

Posted: Sun Jun 14, 2009 8:48 pm
by hugger73hatch
Does it stay at 10 or so just while on the gas, or does it go back up to 34 while still on the throttle?

Also, is it a roller setup?

Re: Erratic timing MSD 6-al

Posted: Mon Jun 15, 2009 5:46 am
by fat bastard
no, it bounces back and forth.

When it goes to ten, its like its skipping/breaking down and then bam, back to 34 and runs ok, this
all happens quickly and no pattern.

Yes it is a roller cam.

Re: Erratic timing MSD 6-al

Posted: Mon Jun 15, 2009 7:28 am
by bbc68nova
were is the box located at on the car
it might be geating to hot

Re: Erratic timing MSD 6-al

Posted: Mon Jun 15, 2009 8:07 am
by coony278
I would be willing to guess that the cam is walking. What kind of front timing chain cover do you have ?

Re: Erratic timing MSD 6-al

Posted: Mon Jun 15, 2009 4:16 pm
by hugger73hatch
coony278 wrote:I would be willing to guess that the cam is walking. What kind of front timing chain cover do you have ?
That is exactly what I was thinking....did you check the camshaft end play on the motor?

Re: Erratic timing MSD 6-al

Posted: Mon Jun 15, 2009 6:18 pm
by fat bastard
-- I'm more inclined to think electronics, small block fords have a plate holding the cam and
timing chain has little to no play. I could be wrong though, wouldn't be the first or last time.

Re: Erratic timing MSD 6-al

Posted: Tue Jun 16, 2009 9:00 pm
by bracketracer
Does that box have a start retard???? Best way to check it is find another box like yours and try it....If the cam is walking it will just retard and stay there while the rpm is up... You should be able to here the tone of the engine change if it does retard 10 degrees...You can also swap a wire and did you think that your timing lite may have taken a dump :scratch: ...

Re: Erratic timing MSD 6-al

Posted: Wed Jun 17, 2009 1:16 pm
by fat bastard
I would love if it where only my timing light taking a dump. At this point I've oredered a new box, dist cap, rotor and
wires.. waiting for the stuff to come from the speed shop.

Will let everyone know when I get it. Still can'T see cam walk on a ford?

I did check out MSDs forum, lots on there about this, still no diffinitive solutions...

Re: Erratic timing MSD 6-al

Posted: Mon Jun 22, 2009 10:40 pm
by BracketNova
I experienced a SIMILAR (ie not the same) problem with my 6AL-2. What timing light are you using? This may not be your problem as you say your car stumbles, etc. (mine does not). On my car I was having a problem with the timing moving about 4000 RPM or so. Below that it would read say 38 ish and move around a little and above 4k it would SNAP go to 42 dead on. After researching forums and not finding anything I waited on hold with MSD fo 32 minutes and they said my timing light was probably not multi-spark compatible. I never thought of this but it totally made sense. The multiple sparks below 4k were freakin out my light and as the owners manual of the MSD says the multi spark feature is shut off at 4K...yealding a true timing reading.

Maybe this does not quite relate to your post...but maybe it will help someone who searches later?

Greg

Re: Erratic timing MSD 6-al

Posted: Tue Jun 23, 2009 11:08 pm
by hugger73hatch
I just thought about something else regarding the timing light. MSD recommends to use a regular timing light, not a dial back type, but I use a dial back and have matched it with a regular light and get the same reading...however, whatever you do make sure none of the timing light wires come in contact with another spark plug wire, especially the inductive lead wire as it will make it jump around like crazy. I had forgot about that until reading the above post...hope this helps!

Re: Erratic timing MSD 6-al

Posted: Wed Jun 24, 2009 7:34 am
by fat bastard
Well, Thank-you all that replied. I must admit sometimes you just don't want to
admit how much you don't know. 1st off, never use a digital timing light to check
ignition timing with an MSD ignition. 2nd don't spend alot of money to guess. 3rd
go back to your basic training and recheck all the obvious things.

Here's what I found after changing, Ignition pick up, dist cap, rotor, wires and
MSD box. I isolated all the wires coming from the MSD and moved everything
away from electric waterpump and alternator. Problem was still there. Then
I took my carb off, swapped it with another one. Miss was better, timing change
better. Not gone. Then as light dawns on marble head. " hey just for kicks, lets try
an older non digital timing light." WOW it stopped.

The lesson here is FOLLOW DIRECTIONS and use the right tools.

But still had a little miss as you throttled up vehicle, appears tobe carb related.
That maybe another post.

Thanks again all that replied.

Fat Bastard

Re: Erratic timing MSD 6-al

Posted: Sun Jun 28, 2009 10:50 am
by hugger73hatch
We've all been there, glad you got it figured out.