Finally replaced the MSD box

[tortuga]

Quite a few people have not a lot of good things to say about the device, so out with it and in with a Daytona sensors cd-1 control box. Pretty straightforward swap out, only bummer is all the empty holes in the passenger footwell, (mounting pattern is totally different)...

The cool part is that the advance curve is programmable, so the next step after getting her fired up in conventional mode (Done) is to interface with the box and program my curve then lock out the distributor. No more silly springs, bushings, weights To mess with...

CD-1




Steve H
SPF 1764

[Gaz64]

Steve,

You'll need an adjustable rotor, and a spare cap drilled with a large hole to verify the rotor phasing versus the whole advance curve.

Gary

[tortuga]

Gary
Please explain?
Thanks

[Gaz64]

With a centrifugal advance distributor, the rotor tip will be aligned to the cap terminal at any rpm.

With a locked distributor, and electronic advance, (which is really a retard), the rotor tip only aligns at about the midway point in the advance curve.

So if we want 30 at 3000, and 14 at idle, a curve of 16 degrees gets split to give 8 each side of middle. So at at 22 degrees, the rotor will be in the middle of the terminal.

You can see this with a timing light, as you rev the engine the spark should go from one side to the other. Otherwise you risk crossfire within the cap.

An adjustable rotor or adjustable pickup is necessary for this to be possible.

Gary

[spdbrake]

I used this MSD video to figure how how to set mine up.

https://www.youtube.com/watch?v=aWMlNwGW0tM

[Michael C Henry]

My car came with a Mallory set up, Distributer, coil, and HyFire ignition box. The original builder had a rev limiter built into the dash.. It turned out that the rev limiter was to operate with distributer and coil.. So the rev limiter didn't work. When I redid Things I bought a newer version of Mallory ignition box that among other thing had a programmable rev limiter. That box crapped out during break-in
When the Mallory box crapped out it had a shorting plug that came with it that eliminated the box for testing and running with out the box. It was concluded that the Mallory box was to blame. The box was still under warranty so I returned and ordered another. It has worked flawlessly for twenty years now. I really liked the Mallory stuff. I was upset when I learned that MSD had taken over Mallory . Competition is a good thing. Why spend to improve with out any competition. My symptom was as I got farther from home the car would run worse and worse so I'd turn the car back towards home thinking it wouldn't keep running, but would idle just fine but getting the car t6 leave the light was terrible. But it idled just great

[tortuga]

Originally Posted by Gaz64

With a centrifugal advance distributor, the rotor tip will be aligned to the cap terminal at any rpm.

With a locked distributor, and electronic advance, (which is really a retard), the rotor tip only aligns at about the midway point in the advance curve.

So if we want 30 at 3000, and 14 at idle, a curve of 16 degrees gets split to give 8 each side of middle. So at at 22 degrees, the rotor will be in the middle of the terminal.

You can see this with a timing light, as you rev the engine the spark should go from one side to the other. Otherwise you risk crossfire within the cap.

An adjustable rotor or adjustable pickup is necessary for this to be possible.

Gary

Thanks I’ve got to wrap my head around this...Really appreciate the heads up, things aren’t always as simple as they seem...

Steve H

[Karl Bebout]

Never thought of myself as particularly lucky, or unlucky, but I had an MSD 6AL in my NAF for 13 years with no problems and I have one in my current ERA for the 5 years I've owned it as well as the 7 years the original owner had the car. The NAF had 30k+ miles and my ERA has 52k+ and I've not any problems. HOWEVER, all that being said, I do carry a replacement spare in the trunk.....

[tortuga]

Originally Posted by Karl Bebout

Never thought of myself as particularly lucky, or unlucky, but I had an MSD 6AL in my NAF for 13 years with no problems and I have one in my current ERA for the 5 years I've owned it as well as the 7 years the original owner had the car. The NAF had 30k+ miles and my ERA has 52k+ and I've not any problems. HOWEVER, all that being said, I do carry a replacement spare in the trunk.....

And mine would probably have gone a million miles, BUT, a lot of guys who I consider to have expertise far in excess of mine have nothing but horror stories about the thing.

I hate having a potential problem in the back of my mind, especially given the remote areas I like to drive. This is especially true when I have my wife along, she’s a trooper, but I feel like an idiot when something goes haywire, not to mention safety...

Steve H
1764

[tortuga]

So I ordered an adjustable rotor and cut a hole in a spare cap next to #1 terminal in order to see the rotor once I get the new rotor.

So the plan is to shoot the rotor with the timing light and adjust it such that the the base and total timing positions are equidistant from centered on the plug post. I’m only running 14 crank degrees between base and total timing so the angle in the dizz should only be 7 degrees.

Guessing that the swept circumference of is on what a 4” circle, the circumference Is about 12.5” or .035”/degree...7 degrees is only .24”, less than the width of the rotor tip.

I’m thinking I should therefore be able to adjust the rotor so that all spark occurs with the rotor tip always next to the cap electrode.

Thanks

Steve H
1764

[Gaz64]

Yes, so rev the engine to half way up the retard curve, and the rotor should be centred on the cap terminal.
The purpose of an adjustable rotor.
Gary

[tortuga]

So I made a check cap out of a spare by hole sawing a window from the top of the cap right next to #1.

With the timing light, initial is just short of the terminal, full advance is overlapped...pretty good, but with the adjustable rotor I’ll be able to get it overlapping all the time.

Thanks again for pointing me down this road! ESP Gary!

Steve H
SP 1764

[Gaz64]

Steve,

Once you get the knack of everything combined, you can target less terminal overlap on the "high rpm side", say 40/60, rather than 50/50.

Gary