msd pro billet distributor

[fryedaddy]

i bought a slightly used msd dist off a round track racer.i have it in my 433 fe.those guys had the heavy springs in it  and the blue bushing.i bought a bush-spring kit for it.i understand how the different springs make the timing advance at different rpms,and the bushings lets you play with the initial timing but i dont understand the ADVANTAGES of witch spring combo to use.i changed the heavy springs to the lite ones so it would advance quicker.i left the blue bushing in.is this ok if not could someone explain about the springs and which ones i need for street/strip

[Drew Pojedinec]

Summit and MSD both have the instructions for these distributors and you can also get a tuning kit if needed (springs and bushings)

[fryedaddy]

I have the chart above and the spring -bushing kit but i dont understand which combo is best for my needs or the advantages of diff. springs

[Drew Pojedinec]

My engines normally wind up with the "E" spring chart and a black or blue bushing.  Lotta factors tho contribute to this tho (cam, converter, etc)
It's kinda like trying to suggest carb jetting, you can guess close, but I don't think anyone could tell you exactly what will work.

This is just from trial testing how it runs in my usage.  I don't think anyone (well maybe someone like Faron that does this all the time) could tell you exactly what works best on your engine.  I've reverted to using Duraspark stuff only, but the same theory applies.  The Duraspark has a tab that can be bent to fine tune spring tension.
If I was you, I'd start with 16-18initial, whatever bushing gets you there and springs that bring advance in near 3,000rpms.  Too high or too low and it feels like you lose some power.  good luck!

[cjshaker]

The bushing is what LIMITS your advance. So add your initial to the corresponding bushing on the chart above to get your total.
Example: if you have 18* initial, the blue bushing will give you another 20* of advance. That would total 38*, which is about perfect.
If you want 40* total, you'd have to go with the silver bushing and back initial off to 15*. 40* is what a lot of iron headed FE's really like, but it really depends on gas quality, which isn't so great in some places.

The blue bushing is nearly always the best given what our engines like for initial (16*-18*), but the springs you can play with easily. I'd start with the 2 blue light springs. Then try the 1 silver (light) and 1 blue (light) and see if your engine can handle the advance coming in by 2500rpm.

[plovett]

I use the "C" curve with the black bushing.  18-19 degrees initial and 36-37 total, all in by 3000 rpm or a bit earlier.

As for what works best for you, it depends on your whole combination.  You can find your best total timing on the dyno, or strip.  Or you can make a good guess depending on what cylinder heads you have. 

The speed of the curve you pick can be influenced by the need to avoid detonation under load.  If your car is heavy or your octane is low, you might want to slow the curve down.

For initial timing, I think more is better, up to a point.  More initial timing makes the off idle response crisper.  Too much initial timing could make it hard to start or make it hard to get a reasonable idle speed with normal adjustments.

I think in general a hot rod FE likes 14-16 degrees initial, 37-40 degrees total, with the total all in by 2500-3000 rpm.  It depends on what your specific combo is, though.

JMO,

paulie

[fryedaddy]

thanks,im starting to understand,i believe i will try the black and blue bushings and try the med. springs and the lighter ones and one of each and see what i come up with.i might try 38 and 40 total with the diff.spring-bushing combos too

[JamesonRacing]

"E" for me, timing is stable below 1000 rpm, then quick to full advance, black bushing as my BP pro-ports like about 33 total, so I can keep the base timing up where it needs to be

[fryedaddy]

JamesonRacing,you are right 66 was a great year for fomoco,me and my dad have several 66s,gt fairlanes,fairlane 500s,comets,and even a 66 pu.1966 in my book was the best all around year for fomoco