MSD 6530 boost retard question - Chevelle Tech
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post #1 of 24 (permalink) Old Jun 25th, 19, 10:42 AM Thread Starter
Kevin
 
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MSD 6530 boost retard question

Iíll be installing a MSD 6530 and MSD pro billet dist (with vacuum adv ) in a few weeks and have a question about setting up a vacuum advance curve. With the mech and vac advance locked out, Iím building a run curve for a big block thatís 16 deg initial 34 deg max all in at 2800.
If I decide to install a map sensor and build a map to allow a 10 degree advance curve, will the run curve need to be modified?


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post #2 of 24 (permalink) Old Jun 25th, 19, 1:15 PM Thread Starter
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Re: MSD 6530 boost retard question

Hope this image will help a little.
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If I build the run retard curve first and upload it will it need to be modified later to keep the same values if I add the boost retard curve and map sensor?
Sorry for any confusion.


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post #3 of 24 (permalink) Old Jun 25th, 19, 2:11 PM
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Re: MSD 6530 boost retard question

The run curve runs independently of anything else. So if you have a run curve taking timing out over x time, say 6 degrees and ramping back in over 2 seconds, and you have boost, say 5 psi with 1įout per psi, then you would have 11 degrees out total for a period of time.


Keep in mind rotor phasing is very important when you are dealing with this.
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post #4 of 24 (permalink) Old Jun 25th, 19, 6:07 PM Thread Starter
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MSD 6530 boost retard question

Thanks for the reply. Iíll have to do a lot more research to fully understand most of it the timing x time with boost retard threw me a curve. I do remember seeing a comment on phasing the rotor but havenít started reading up on it yet.
Point and condenser I can do, the electronic versions not so much.
If I understand this correctly (and to bring it down to a level I can start to understand), if I install the locked distributor, set it at 16 deg btdc at an idle I should have approx 36 deg btdc at 3200 rpm and up with only the first chart uploaded.

When I install the map sensor and upload the second chart, I should have the same timing curve as before with an additional 10 degrees when the vacuum conditions allow. (?)

If anybody has suggestions for additional information on this please post (or im) the links. While a little overwhelmed itís been an interesting read. Thanks again.



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post #5 of 24 (permalink) Old Jun 25th, 19, 6:39 PM
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Jim
 
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Re: MSD 6530 boost retard question

No. You have to install the locked out distributor at the highest point of timing advance that you want the engine to see throughout its rpm and load range. The 6530 can only retard timing, it cannot add degrees of timing. For example, I set my distributor in locked at 40 degrees advanced. My run curve has a start retard of 10 degrees from 0 to 600rpm for easier starting. My engine idles at 900-1000rpm and likes the 40 degrees of advance at idle and low load cruise when vacuum is at its highest. Overall, after the start retard, my run curve retardis zero. Now, I donít want to be under moderate to high engine load with timing at 40 degrees, this is where the map sensor (vacuum curve) comes in and retards timing as vacuum drops, at full throttle, and very low/no vacuum I pull a total of 8 degrees from the timing yielding 32 degrees. Hope that helps.
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post #6 of 24 (permalink) Old Jun 25th, 19, 6:46 PM
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Re: MSD 6530 boost retard question

btags beat me to it. He is correct. the 6530 can only retard timing. So based on your screen shot you would be installing the locked distributor at 38 degrees. That would mean pulling 22 degrees to get to 16 degrees. This would likely lead to a cross firing situation as that is a ton of timing to pull.

As Rick mentioned, rotor phasing plays a big part in all of this but I just don't know if even a perfectly phased rotor would work with pulling 22 degrees. But it might....I just haven't tried it.
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post #7 of 24 (permalink) Old Jun 25th, 19, 7:36 PM Thread Starter
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Re: MSD 6530 boost retard question

Quote:
Originally Posted by btags View Post
... start retard of 10 degrees from 0 to 600rpm for easier starting ... Hope that helps.

Start retard is 10 degrees off of the 40 total timing?

Big help, thanks.




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post #8 of 24 (permalink) Old Jun 25th, 19, 7:45 PM Thread Starter
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Re: MSD 6530 boost retard question

Quote:
Originally Posted by Greg Owens View Post
btags beat me to it. He is correct. the 6530 can only retard timing. So based on your screen shot you would be installing the locked distributor at 38 degrees. That would mean pulling 22 degrees to get to 16 degrees. This would likely lead to a cross firing situation as that is a ton of timing to pull.



As Rick mentioned, rotor phasing plays a big part in all of this but I just don't know if even a perfectly phased rotor would work with pulling 22 degrees. But it might....I just haven't tried it.


Thanks for commenting on the amount of timing in these curves. To be honest, I was just tryIng to get the timing at cranking as close to the factory spec as possible to keep from overloading the stock starter. I didnít realize I was pushing the limit that far.


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post #9 of 24 (permalink) Old Jun 26th, 19, 8:00 AM
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Re: MSD 6530 boost retard question

With a vac. advance distributor why use a map sensor?
Wouldn't it be better to use the distributor vacuum can?

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post #10 of 24 (permalink) Old Jun 26th, 19, 9:46 AM Thread Starter
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Re: MSD 6530 boost retard question

Quote:
Originally Posted by LaVelle View Post
With a vac. advance distributor why use a map sensor?

Wouldn't it be better to use the distributor vacuum can?


With the map sensor the software is able to build a curve using any vacuum values you want. So if youíre running a cam that isnít creating a lot of vacuum you can still build a curve for it. At least thatís my take on it. You can also set the number of degrees you want added.


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post #11 of 24 (permalink) Old Jun 26th, 19, 9:57 AM
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Re: MSD 6530 boost retard question

Quote:
Originally Posted by LaVelle View Post
With a vac. advance distributor why use a map sensor?
Wouldn't it be better to use the distributor vacuum can?
No, because digitally you can make micro changes via a keyboard on a point by point graph. So lock out the distributor and do everything electronically.

If you want to keep VAC advance you might as well just put a simple ignition amplifier in there, because it's a total waste of the 6530's capabilities.

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post #12 of 24 (permalink) Old Jun 26th, 19, 9:11 PM Thread Starter
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Re: MSD 6530 boost retard question

Quote:
Originally Posted by Calculated Risk View Post
The run curve runs independently of anything else. So if you have a run curve taking timing out over x time, say 6 degrees and ramping back in over 2 seconds, and you have boost, say 5 psi with 1įout per psi, then you would have 11 degrees out total for a period of time.





Keep in mind rotor phasing is very important when you are dealing with this.


I finally found a little info on delayed step retard settings in the help files but canít really understand the benefits just yet. This system has a lot of functions to explore, some are a little confusing at best.

Found quite a bit on rotor phasing but didnít see anyone using a clear cap. Would that be an option instead of drilling a cap?



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post #13 of 24 (permalink) Old Jun 26th, 19, 9:16 PM
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Re: MSD 6530 boost retard question

Quote:
Originally Posted by flht01 View Post
With the map sensor the software is able to build a curve using any vacuum values you want. So if youíre running a cam that isnít creating a lot of vacuum you can still build a curve for it. At least thatís my take on it. You can also set the number of degrees you want added.


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The MSD Graph View software for the MSD 6530 will not ever add timing. It can only retard timing. The MAP based curve is boost retard. It can only remove timing under boost. It cannot add timing under vacuum. So if you are naturally aspirated there is no reason to add the MAP sensor.

At least that is the case with the version I have but it is 5+ years old. They may have changed it.
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post #14 of 24 (permalink) Old Jun 26th, 19, 9:25 PM Thread Starter
Kevin
 
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MSD 6530 boost retard question

Quote:
Originally Posted by Greg Owens View Post
The MSD Graph View software for the MSD 6530 will not ever add timing. It can only retard timing. The MAP based curve is boost retard. It can only remove timing under boost. It cannot add timing under vacuum.

I got my words a little backwards but understand the logic, at least a little better than before. BTW, If the MAP sensor reading is 14.75psiA or less, its actually vacuum. With these readings you can manipulate the timing based on vacuum in addition to the rpm curve.

When youríe using two curves at the same time it gets a little confusing. The way I have it figured, the boost curve will remove timing in addition to the run curve. I think...


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post #15 of 24 (permalink) Old Jun 27th, 19, 5:03 AM Thread Starter
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Re: MSD 6530 boost retard question

Quote:
Originally Posted by flht01 View Post
... BTW, If the MAP sensor reading is 14.75psiA or less, its actually vacuum. With these readings you can manipulate the timing based on vacuum in addition to the rpm curve ...
I found this topic
https://lateral-g.net/forums/showthr...t=48612&page=4
starting at post 34 helped with understanding the map sensor and vacuum.
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