MSD 6421 or 6425 or 6530 or 6462

yellowstang

Well-known member
ok trying to pick my ignition. ( in case i haven't said it; Thankyou for helping me!)

I have 1968 mustang convertble, 200 cu in, 3.3L in-line 6.

Isky 256 cam, 202@.050, .450 lift, 112LSA

I am putting on a turbo and intercooler. blow thru a holley 8007 390cfm 4bbl progressive carb.

recently purchased duraspark2 dual vaccuum 30-2670 and mr gasket 925D( only 1 spring).

will I need the 6421 suit me or do I need the 6530. is the 6462 better than all 3. all look great. the 6530 is about $100 more than the 6421

Let me know,
Pete

MSD 6AL
 
The 6462 will only control timing during boost and you get to program how many degrees per lb of boost to retard the timing. Linear relationship only.
The distributor's mechanical advance and vacuum advance will need to control the rest of the timing as usual.
The rev limiter is controlled using RPM modules which are purchased separately.

The 6530 controls all of the timing and lets you program the mechanical advance as well as the vacuum advance and boost retard.
The programming is done by a timing versus rpm curve for the mechanical advance and a timing versus absolute manifold pressure for the vacuum advance and boost retard.
The distributor's mechanical advance and vacuum advance will need to be locked so the distributor can deliver a steady reference signal to the MSD 6530.

Because the programming is done using a curve it does not have to be linear and you can create any timing relationship to rpm or manifold pressure/vacuum you want.

The 6530 also has 3 rev limiters, burnout, launch and upper limit and are programmed with the software. No rpm modules needed.
There is also a step retard for nitrous or you can use it to retard the timing during starter cranking.

You will have to purchase a MAP sensor to work with the 6530. 2 Bar for up to 15 lbs of boost or 3 bar for up to 30 lbs of boost.
 
The MSD box is a good piece but the software is kind of hard to understand. Also, in addition to the pricey box, you need to purchase a MAP sensor.

Take a look at the CB Performance Black Box. 3D mappable ignition using a locked out distributor. MAP is built in. Best part is it's half the price of the MSD. Works on 4-6-8 cylinders engines.

http://www.cbperformance.com/Articles.asp?ID=320
 
Why not just do EDIS? Stupid-simple to install and tune and fully programmable. Not much more to build this than the 6BTM and far, far better.
 
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