MSD6AL is down and had to revert to an HEI module until the MSD is repaired.

[63 Sprint]

The MSD6AL is not energizing when ignition is turned on. I needed the truck for a job. For now, I’m using an HEI module. I noticed fuel consumption increased in the past couple days. It looks like I’m getting just under 2 mpg loss in economy. So, it seems like, that it could be true that the MSD improves fuel economy. I noticed that my foot is now more on the throttle. Loosing just under 2 mpg is a considerable loss in economy.

I will verify the results when I get the MSD going again.

 

[63 Sprint]

Well, this morning the truck would not start up. Ran some tests and it looks like the EEC relay near the original air cleaner location is not working. This relay switches the 12 volt power on and off to operate the MSD 6AL and for now, the HEI Module.
Searching nearby junk yards of the relay. I’m thinking that the MSD box might still be ok. Hopefully I’ll know something later today.

 

[63 Sprint]

Found a matching relay at an LKQ pick and pull. Pretty much cost me $3.00 admission fee and some gas. They did not charge me for the part.

At Autozone it would have costed about $26.00 plus tax.

Put the relay in and the truck fired right up. So, the HEI module along with the adapter was removed and the MSD was plugged back in. The MSD works fine. What a relief.

Have not taken it out on the road yet. Possibly later. Just glad it’s back up and running once again.

 

[bmbm40]

picnpulls are awesome.

 

[63 Sprint]

Just got done with driving the same route and I can verify that there is a slight difference.

It’s not as much as I expected. The reason why is when the tank was topped off on Friday afternoon before taking a test drive with the HEI module the truck was driven on back country roads with a top speed of 50 mph for the past week.

When I tested the truck the first time with the HEI module I was driving on the highway at 65 mph.

Today, when the MSD was plugged back in, I ran the same highway route at 65 mph.

The results showed:
With HEI Module
•. Miles driven: 73.3 miles
•. Fuel tank topped off: 4.469 gallons
•. MPG: 16.4

With MSD6AL Box
•. Miles driven: 73.3 miles
•. Fuel tank topped off: 4.141
•. MPG: 17.7

A 1.3 mpg difference with the MSD6AL on the top.

The test would have been more accurate if I ran through at least 3/4 of a tank on both tests. So there is a greater margin of error.

The test costed me $32.00 and some change. At least we have some sort of numbers to go on.

Driving impressions:

With HEI Module
Truck ran fine, I noticed that I had to push down slightly more on the pedal than what I’m used to.

With MSD6AL
Truck ran like I’m accustomed too. Less pedal pressure needed. Actually, once the truck reaches 65, I get the feeling of backing off on the pedal slightly and the truck maintains speed. Truck feels like it’s running normal. I’m used to this feel.

Is there is a difference? Yes.

Is the test accurate? Not as well as it could have been. The numbers could be a + or - either way.

Is it a huge enough of a difference to consider installing an MSD box? It’s up to the individual to decide.

If a person hardly uses the truck throughout the year, probably not.

If a person uses the truck often and racks up thousands of miles a year, probably something to consider.

 

[Bronctopia]

Umm, is this truck running on a carb, stock EECIV efi, or some third party fuel injection?

 

[63 Sprint]

1989 stock EFI engine with:

• Stock EFI exhaust manifolds

• Offenhauser C

• 1 inch thick, 4 hole, aluminum spacer with the same bore diameter as the Holley 390 bores.

• Holley 390

• DSll distributor (re-curved)

• MSD6AL

 

[Bronctopia]

Thanks.
Any idea what AFR you are running at highway cruise?
Stock EFI is limited to stoich, but carbs and "others" could go leaner.
I'm wondering if the hotter spark is most notable in "lean burn".

 

[63 Sprint]

Cruising the AFR reads 13.7 - 14.2
Don’t want to go any leaner. No anti knock protection. The truck hauls some pretty good loads.

The jetting allows me to use:
Ethanol Free fuel 89 - 91 octane.
E-10 fuel 89 - 93 octane.

 

[PSIG]

Stock EFI is limited to stoich, but carbs and "others" could go leaner.
I'm wondering if the hotter spark is most notable in "lean burn".

Correct, and a big part of economy tuning and reducing pumping losses. High-energy ignition (HEI, Ford TFI, DS-I, P-II, etc) consistently allows better fuel economy with wider plug gaps when tuned properly, than CDI (MSD, P-III, etc), and one reason the OEMs use it and not CDI. I and others have repeatedly shown HEI to properly light 0.5 to 1 AFR leaner than CDI consistently. CDI is great for rich AFRs, drilling through polluted mixtures such as radical cams at idle, 2-stroke oily fuels, extreme rpm, etc, but the spark is sharp and thin and lights fewer fuel molecules on each spark. One reason they fire multiple sparks when possible. That's the general gist of it and why CDI is usually not the top pick for street and most racing these days.

However, using HEI will not gain you economy unless tuned to take advantage of it. Stock EFI is limited in the AFRs it can run, and inconsistent without WBO2. Other factors such as constant high-throttle heavy load towing may not allow enough power at cruise for leaner tuning. So while HEI should make better mileage, and is used in racing for this reason (less fuel consumption = reduced race weight or fewer stops), certain conditions or EFI systems may preclude effective economy tuning for certain conditions.

[EDIT]

Cruising the AFR reads 13.7 - 14.2
Don’t want to go any leaner. No anti knock protection.

That's very rich for cruise, including stock. Typically with our engine designs, the low to mid-16:1 range burns cooler and much better economy. AFR heads can do this. However, the ignition must be tuned for the AFRs to burn properly and not too late, causing latent heat and potential detonation. Ignition tuning is a must.

 

[pmuller9]

What 63 Sprint has found is also what several others have experienced specific to the 300 six.
The MSD 6A and 6ALs offer a noticeable increase in both low rpm power and fuel mileage when compared to other ignition systems including other CDI units on the same engine/vehicle.

 

[sixtseventwo4d]

63 Sprint, where do you have your main power and ground connections?

 

[63 Sprint]

As MSD recommends. Right on the battery terminals.

 

[63 Sprint]

The alternator has been upgraded to the large frame 3G. So there is no problem with voltage. The wiring has also been upgraded to handle the load.

 

[bmbm40]

Just got done with driving the same route and I can verify that there is a slight difference.

It’s not as much as I expected. The reason why is when the tank was topped off on Friday afternoon before taking a test drive with the HEI module the truck was driven on back country roads with a top speed of 50 mph for the past week.

When I tested the truck the first time with the HEI module I was driving on the highway at 65 mph.

Today, when the MSD was plugged back in, I ran the same highway route at 65 mph.

The results showed:
With HEI Module
•. Miles driven: 73.3 miles
•. Fuel tank topped off: 4.469 gallons
•. MPG: 16.4

With MSD6AL Box
•. Miles driven: 73.3 miles
•. Fuel tank topped off: 4.141
•. MPG: 17.7

A 1.3 mpg difference with the MSD6AL on the top.

The test would have been more accurate if I ran through at least 3/4 of a tank on both tests. So there is a greater margin of error.

The test costed me $32.00 and some change. At least we have some sort of numbers to go on.

Driving impressions:

With HEI Module
Truck ran fine, I noticed that I had to push down slightly more on the pedal than what I’m used to.

With MSD6AL
Truck ran like I’m accustomed too. Less pedal pressure needed. Actually, once the truck reaches 65, I get the feeling of backing off on the pedal slightly and the truck maintains speed. Truck feels like it’s running normal. I’m used to this feel.

Is there is a difference? Yes.

Is the test accurate? Not as well as it could have been. The numbers could be a + or - either way.

Is it a huge enough of a difference to consider installing an MSD box? It’s up to the individual to decide.

If a person hardly uses the truck throughout the year, probably not.

If a person uses the truck often and racks up thousands of miles a year, probably something to consider.

I enjoyed the information you provided, very informative and appreciate your effort as well.
Pretty impressed that a full size pickup is getting 17.7 highway. Considering how many gallons used for driving over the years you own it will be a reduction in fuel costs, maybe not substantial but still money in your pocket.

 

[PSIG]

+1, tuning for both power and economy can reap large benefits. While not typical, one of my favorites was a '91 R2500 350 that improved 38% mileage economy with lean-burn and ignition tuning, and improved power as well. We're talking almost 20 years ago with basic TBI EFI, that saved (with those gas prices) over $900 per year in fuel costs. The ECM upgrade cost less than $200, plus tuning time. Keep in-mind the gains were mostly due to horrible regulatory emissions tuning for those years, but it would still pass emissions while making far better economy everywhere else in the operating range.

It proved MPFI was not the big improvement, but better control and tunability (tuning data interface) no matter the fueling control type. The changes in fuel tuning have forced changes in ignition types and tuning to support them. It's not all about power tuning and rich or stoich AFRs anymore (actually for a long time now), and ignition is the team-mate to fuel for optimal efficiency (power and economy) in one package. Interesting IDI vs CDI here: https://www.onallcylinders.com/2014...h-capacitive-discharge-vs-inductive-ignition/

 

[wsa111]

+1, tuning for both power and economy can reap large benefits. While not typical, one of my favorites was a '91 R2500 350 that improved 38% mileage economy with lean-burn and ignition tuning, and improved power as well. We're talking almost 20 years ago with basic TBI EFI, that saved (with those gas prices) over $900 per year in fuel costs. The ECM upgrade cost less than $200, plus tuning time. Keep in-mind the gains were mostly due to horrible regulatory emissions tuning for those years, but it would still pass emissions while making far better economy everywhere else in the operating range.

It proved MPFI was not the big improvement, but better control and tunability (tuning data interface) no matter the fueling control type. The changes in fuel tuning have forced changes in ignition types and tuning to support them. It's not all about power tuning and rich or stoich AFRs anymore (actually for a long time now), and ignition is the team-mate to fuel for optimal efficiency (power and economy) in one package. Interesting IDI vs CDI here: https://www.onallcylinders.com/2014...h-capacitive-discharge-vs-inductive-ignition/

With a carburetor & ethanol fuel you best keep your A/F ratio cruising close to the 14.5 area, WOT keep in the 12.3-12.5 range.
Non ethanol you can lean cruising closer to 14.8-15.0 area, WOT 12.8-13.1.
Since you are running an intake manifold mixtures can vary.
With direct port fuel injection & a computer, mixture is consistant to all cylinders so your engine is can handle possible leaner mixtures.
Don't try to convince our members to run those lean mixtures with a carbutor & intake manifold.
I am going to lock this thread for the safety of possible engine damage.