MSD Ignition

[EagleMark]

This covers wiring of MSD 6a in all applications including installing it in a stock EFI system.

[Six_Shooter]

The ignition module gets connected to the ECM, to both trigger the ECM and allow the ECM to control timing. The igniton control module also triggers the MSD box. Look at the points trigger setup using the white wire.

[JeepsAndGuns]

Ok now I'm getting confused. Are yall saying he can use the MSD box instead of the 8 pin HEI module (for the op, thats the ignition module used with a the 16197427 pcm we are talking about, and many others) Or are yall saying he can continue to use the MSD box WITH the 8 pin module?

[Six_Shooter]

He can use the MSD box with the 8 pin module.

[EagleMark]

Yup!
http://www.msdperformance.com/product.aspx?id=4685

[JeepsAndGuns]

He can use the MSD box with the 8 pin module.

Not to highjack the thread. But next question is why would you want to install the msd box? Looks like its simply going inbetween the coil and the stock harness, so whats it really doing? Seems like simply adding un needed parts that could fail or make problems.

[EagleMark]

Really it's not needed and wears out cap, rotor and spark plugs 3 times quicker.

It fires spark three times at low RPM and one time longer at high RPM.

Really helps in very rich old carbs with big cams. Helped to keep cars on carbs running WAY rich when Nitrous was not on and no way to add fuel like with EFI.

[FSJ Guy]

Not to highjack the thread. But next question is why would you want to install the msd box? Looks like its simply going inbetween the coil and the stock harness, so whats it really doing? Seems like simply adding un needed parts that could fail or make problems.

Why not? It gives you multiple sparks below 3,000 rpm. If it does fry and let the smoke out somehow, you simply unplug the connector harness and put the connectors back together with the OEM system. The make a plug n play harness for the GM dual connector coil.

[Six_Shooter]

The MSD provides a hotter spark than without. I would use an MSD box with a dizzy, due to all of the gaps that the spark has to juno on it's way to the plug. On DIS systems they don't provide as much of a gain or benefit.Caps and rotors don't wear out any quicker than without an MSD box.

[EagleMark]

Caps and rotors don't wear out any quicker than without an MSD box.How can you say it won't wear out cap and rotor faster with hotter spark three times more often? It will also disenagrate a cheap quality cap rotor button leaving the spring dangleing in distributor! Using one on a large cap HEI distributor, carb 454 truck, we burned up three coils half way to Texas from Idaho, removed MSD box and drove the other half way to Texas and back home on one coil no failures. All personal experiances...

If your going to use an MSD box then use MSD Cap, Rotor, Wires and Coil. This is the only way I never had a failure, but also was not a daily driver or did long highway trips.

[Six_Shooter]

I've installed many MSD boxes on cars using stock ignition components, I can't recall one premature failure of any part. I had a 6AL installed on my Sunbird and Skyhawk for about 2 years before I did an engine swap to an engine with DIS, never experienced any premature failure of ignition components.About your experiance, the first thing that comes to mind is poor grounding of the coil, the next thing is something wrong with the components used. Many people, myself included have used MSD boxes on in cap HEI coils without issue.

[1project2many]

FWIW I've badged MSD as Must Soon Die. The race grade products are worth owning and there are systems built in the '70s and '80s that are still working fine today. But the consumer grade products are completely hit or miss, and when they're a miss they're a big miss. I've been left stranded in 3 of my own cars due to failures in an MSD ignition system over the years and I've diagnosed issues ranging from misfiring cylinders to poor quality REF signals to misinterpreted timing signals and random stalling back to consumer grade boxes.

Large cap HEI in stock form will spark across a .100" plug gap with plenty of energy. Stock DIS systems in good shape can easily throw spark across .500" gaps. Unless you're running in an RPM range where the stock ignition system is having trouble or you have a specific set of conditions that are causing the stock system to perform insufficiently, I personally see no need to spend extra money on an MSD. If anything I'd get an improved aftermarket module and adjust the computer controlled dwell period in the stock calibration for slightly longer spark.

More sparks in a given time frame can definitely cause more frequent parts failure. LT1 owners are probably familiar with GM's Optispark vent campaign in the early cars. Ozone created when sparks occur plus moisture in the cap would react and create nitric acid which would quickly degrade the rotor, cap, and even the distributor itself. The positive ventilation installed in the Opti ensured no buildup of ozone or nitric acid. I've used that same thinking plenty of times on standard distributors. Small cap HEI distributor rotors often get "stuck" to the shaft due to rust and I've seen the insides of the distributor full of corrosion from the terminals in the cap while the end of the rotor just sort of dissolves. In my '57 I cut the end off an old carburetor dashpot with a .020" orifice and installed it in the small cap dizzy. I connected the other end to ported vacuum so air would only draw through when the throttle is open. That was in '93. I have never changed the cap or rotor and they are still in great shape today. In our 5.7 Vortec vans we have problems with moisture buildup in the cap after a large rainstorm or on days with high relative humidity and large temperature swings. It's so bad it can actually cause a no start. In the 20 or so repeat offenders that I've installed positive ventilation the moisture problems are completely gone, and we've moved from changing the cap/rotor at 40-60k mile increments to changing it at 100k mile increments (or when the dang plastic body fails). When using a multiple spark or high voltage spark ignition in a street distributor I would definitely consider a similar modification. The more sparks occur, the more ozone is present, and the greater the potential for acid formation.


Wasn't there an LT1 manifold swap somewhere in this thread?? :)
EDIT: EagleMark Thread Split

[EagleMark]

So that's what that green corroision is?

FWIW the LT1 vent system is sold new still for like $56. It consists of vacuum line, an elbow to intake, a filter that looks like a one way valve (haven't tested if it is) on intake side to engine and I think... something else on intake to distributor... have to look later. I may do this upgrade on my Suburban as it was greenish inside last cap and rotor change about 4 years ago...

[Nasty-Z]

I had a 6AL installed on my Sunbird

Funny you should mention that , I had a 6AL box on my daily driver Sunbird years ago also , simply because I could .....

I will join the no problems club here , MSD ignition boxes , distributors , and electronics since I was old enough to buy them , I have never had a failure , or have experienced premature failure of any quality component.

TOM

[PJG1173]

I run crane HI6 products in my two projects. haven't had any issues which I attribute to they are full digital unlike the MSD unit. I really didn't see any improvement by installing them though. I use them mainly for rev limiters since I would rather cut spark than fuel.

[JeepsAndGuns]

Ya know, after watching that vid mark posted about the optispark, and reading this, I am almost tempted to add a vaccume line ent to the distributor cap on my wrangler. I have a aftermarket coil on it and use the BWD brass terminal cap/rotor, and every time I change it, there is always this thick golden brown film on the inside of the cap. I'm about due for a change, I might try this. Anyone know of a orifice I could install in a vac line? I doubt I need a full open vac line, probably too much of a vac leak.

[93V8S10]

No problem here with the ignition boxes, but I will never own another MSD distributor. Lots of moisture and corrosion, went to start it one rainy day and the darn thing jumped spark so bad that the engine kicked back so hard that it broke the starter drive.

[1project2many]

Anyone know of a orifice I could install in a vac line? I doubt I need a full open vac line, probably too much of a vac leak.

What I've been doing lately is using a 90 degree elbow for 1/8" vacuum / washer hose. I put a paper clip or small wire in one end, mix up a little epoxy and fill the fitting around the wire, and as the epoxy is hardening I pull wire out. Give a .020" - .040" orifice.

[gregs78cam]

I was thinking about putting a fitting in base of the distributor, run a small hose to a check valve and then over to the valve cover opposite the PCV. So that all air that gets sucked into the crankcase comes from the distributor cap. Any problems with this thought?

[EagleMark]

that's not going to be near enough air on it's own...

[1project2many]

So that all air that gets sucked into the crankcase comes from the distributor cap. Any problems with this thought?

Possible problem if the check valve fails and lets crankcase vapors back into the cap under pressure. Could make a mess or worse.

[EagleMark]

You should have plenty of left over ported vacuum ports on those 2 TBI units!

I haven't had time to search yet for a simple one way valve or one way valve with filter or just filter for vacuum line. There should be plenty of options from conglomerations of vacuum lines, valves, switches from carburetors cars around 1986 down before EFI. Remember what a mess they were? Well there's the parts we need!

[JeepsAndGuns]

What I've been doing lately is using a 90 degree elbow for 1/8" vacuum / washer hose. I put a paper clip or small wire in one end, mix up a little epoxy and fill the fitting around the wire, and as the epoxy is hardening I pull wire out. Give a .020" - .040" orifice.

That sounds like a good idea, I may just give that a try!

[1project2many]

You should have plenty of left over ported vacuum ports on those 2 TBI units!

I haven't had time to search yet for a simple one way valve or one way valve with filter or just filter for vacuum line. There should be plenty of options from conglomerations of vacuum lines, valves, switches from carburetors cars around 1986 down before EFI. Remember what a mess they were? Well there's the parts we need!

Windshield washer hoses often have a check valve. 96+ Chrysler Co. minivans are one option but they're under the cover under the wiper arms. S10 Blazers usually have them in the hose to the rear washer somewhere near the washer bottle. These valves usually have a stainless checkball and spring because washer solvent is Methanol and very corrosive. But I can't tell you how much vacuum it takes to open one 'cause this is a whole new application. :)

[EagleMark]

Good idea! Wouldn't have even looked there cause there's so much stuff available from vacuum side of those diaster engines of that period. Your idea may be cheaper, easier to find in JY.

But back to Opti Vented it is specifically a filter first coming from distributor going to vacuum, I do not know if it's a one way also, One way may be thing in vacuum line to distributor?

Just have to find time to research it and the perfect parts will come together.