Posted By: kick_the_reverb
Stupid question - lockout dist but have vacuum advance? - 11/29/09 04:01 PM
Hi, this might be a pretty stupid question, but I haven't messed with distributors, so here goes:
I bought a used MSD 6530 programmable 6al-2. But reading more into the instructions I realized it has boost retard, but not really vacuum advance.
So, I know there are some workarounds with the programmable map, but was wondering if there's a way to lock out the mechanical advance of a stock distributor, yet retain the vacuum advance capability?
Thanks,
Ran
Posted By: skep419
Re: Stupid question - lockout dist but have vacuum advance? - 11/29/09 05:40 PM
I believe the answer is no. If you lock out your dist. Your full in all the time. Where the vacuum advance would ad timing with less vacuum.
Not for sure but thats my understanding.
Posted By: Evil Spirit
Re: Stupid question - lockout dist but have vacuum advance? - 11/29/09 06:54 PM
Mechanical and vacuum advance are two separate sections in the dist, and can be modified as needed. You can lock out the weight system so it doesn't change with RPM, and use the ported vacuum port of the carb connected to the vacuum pod to get some advance out of the dist. I don't know what exactly you are trying to do, so unless you want to spend a lot of trial and error time, a programmable dist might be a better option for you.
As to stupid questions, I read them here all the time. A "stupid question" is one that is asked without making an attempt to find the answer first. Some people make no attempt to figure things out on their own; instead, they just fire off questions, expecting others to do their thinking for them. IMO, those are "STUPID QUESTIONS".
Posted By: kick_the_reverb
Re: Stupid question - lockout dist but have vacuum advance? - 11/29/09 09:48 PM
Thanks guys.
To further explain:
Street vehicle - I always want to have vacuumm advance.
Will be adding a blower in the future, so I liked the idea of the programmable 6al-2, which already has a boost retard function and a programmable advance curve through software.
BUT - I didn't read enough before buying it, I assumed it had the function of vacuum advance like the programmable E-Curve distributor. Turns out it doesn't.
The unit requires a locked out distributor at full total timing, and you can plot the curve so the unit retards as much as you want according to the curve.
It has the option of using one of three MAP sensors:
1-Bar, for normally aspirated engines, PN 23111
2-Bar, for 2-30 psia, PN 23121
3-Bar, for 2-45 psia, PN 23131
So...I was reading that for N/A one can get the 1-Bar MAP sensor and get some "vacuum advance" - lock out the distributor at say 50-52 degrees, and as less vacuum "more boost" comes in, you retard it.
But, what happens when I add a blower? I'll have to jump to the 2-Bar MAP sensor, and then that function won't really work.
So, if I can lock out the centrifugal advance in the distributor, but retain the vacuum advance, I can basically plot the mechanical advance curve through the program, and keep the vacuum advance simple with the vacuum canister.
So, from the last two replies I'm getting that it is feasible. I'll be happy to hear some more opinions.
Thanks,
Ran
Posted By: Anonymous
Re: Stupid question - lockout dist but have vacuum advance? - 11/29/09 10:30 PM
i don't get why you want vacuum advance. you have a programable msd. either use the preset curves or custom program your own.
but there is no way to lock a dizzy and still use the vacuum advance on the dizzy. you'd hafta get a lean burn for that.
Posted By: kick_the_reverb
Re: Stupid question - lockout dist but have vacuum advance? - 11/30/09 12:55 AM
Thanks guys...
Ghost, I want vacuum advance because it's not a race vehicle. I have no problem plotting the mechanical advance using the software.
Just to make sure we're clear - I'm talking about an MSD 6al-2 p/n 6530 which is an ignition box, not a distributor.
So if going by what aarcuda says, the Mallory style/new MP should have that capability, and the stock type might not.
I guess I'll find out when I start messing around with the distributor.
Thanks,
Ran