this 77 I been working on has a Msd 6AL system, can anyone tell me about it, it is limited to 6000 rpm, I want to change that, HOW!!! Also does this replace the ignition module or what is the real purpose.

attached is a picture of a part of it what is it !!

Thanks

Think the mod# is 6420

MSD-6AL has plug in "pills" or "modules" set at 100rpm increments that limit rpms in it circuitry. Haven't seen one like what is in your picture... here is more info. on the MSD unit.

http://www.msdignition.com/ignition_6_6420.htm

http://www.msdignition.com/pdf/6%20series/6series.pdf

http://store.summitracing.com/partdetail.asp?autofilter=1&part=MSD%2D6420&N=700+115&autoview=sku

2 & 3 step soft touch rev control modules are also available for adding timing control into your rev limiting too.

I use the MSD-6AL unit mounted under the passenger side glove box area protected from heat, moisture & vibration, with a 7000rpm pill installed. I also use an adjustable rpm shift light.

http://proformparts.com/PDF/ShiftLightInstructions6.pdf

http://store.summitracing.com/egnsearch.asp?N=700+400405+115+304978&autoview=sku

Good Luck.

Good info from Chino. To answer the other part of your question it does two functions. One is "capacitive discharge". This means instead of charging the coil with 12V to get the spark, the MSD uses a capacitor to bump that up to a higher number, I think its around 450V. It doesn't charge the coil for as long, but running more voltage to the coil means a higher voltage spark. Under 3000 rpms it will also produce 3 sparks per power stroke. Over 3000 it reverts to one. This is especially an especially good feature for old carbureted cars and will make them run smoother at lower rpms. The MSD also replaces the module in an electronic ignition system.

You can wire it up to run in conjunction with the stock module, but then the MSD is only doing its capacitive discharge thing, and not doing the module thing. I had my own setup running like this for a long time, then I found out it could be done the other way. It just makes sense to me that if the MSD can do it, it should, as that eliminates one more point of failure from the system.

That picture you have is not the 6420, by the way. http://www.msdignition.com/ignition_6_6420.htm

You'll find MSD's have something of a reputation for failure. I've run mine for a long time and never had a problem, but you'll find both sides of that story online. A friend of mine dynoed his 510 with Mikunis back to back with stock EI and the MSD and gained 9 or 10 hp with the MSD in a car that was putting down ~100 whp. I feel it's a good bargain.

That looks like an adapter for your tachometer. Sometime necessary when installing MSD-6.

Yep, some tachs and injector systems won't recognize the trigger signal and need this adapter to convert it to be recognized... looks sorta like this one.

http://www.msdignition.com/pdf/8910_21247.pdf

http://cgi.ebay.com/ebaymotors/MSD-8910-Tach-Fuel-Adapter-for-Pre-1989-Honda-SCI_W0QQcmdZViewItemQQcategoryZ33691QQihZ020QQitemZ300075316223QQtcZphoto

The adapter unit is used with the MSD-6AL box.

ok we're getting there, now how about the pills in this thing for rev limit, where are they located and were can I get one for say 7000 rpm!

They plug into the side of the MSD unit and they say the limit right on them. Shouldn't be hard to find. Any MSD supplier will have different pills. You can purchase them in 1000 rpm ranges by 200 rpm increments, so you might get a pack that has 6200, 6400, 6600, 6800, and 7000.

If you call Summit Racing they could possibly get you a set in the range you wish to limit your rpms.

Example: http://store.summitracing.com/partdetail.asp?autofilter=1&part=MSD%2D8745&N=700+115&autoview=sku

If you have a one now you can remove the chip or pill that is plugged into the side of your unit and see what is printed on it, should give you the rpm limit...say 6000. I think you can remove the pill and it will run just fine, but will have no limit (just be carefull). I believe I was doing some testing in the past with and without the pill... I had a problem of not being able to get above 5800rpms. It happen to be fuel supply and not an rpm limiting problem at the upper end. But you can test yours by removing it to verify it is being limited by a pill or perhaps you are seeing a different problem?

You can download the manual for it from the MSD website. It doesn't say much about the rev limiter that hadn't already been said. It's just as simple as replacing the module the the RPM limit you want. The item you pictured in your first post is actually the Tach Adapter needed to get many older tachs to work with the MSD ignition in place, but I'm assuming you know that by now.

Here's a link to the manual:

http://www.msdignition.com/pdf/6%20series/6series.pdf

great info guys,wet sanding right now but within a week time to fire it up again, wanna have all my ducks in a row!