427 SO Timing/cooling fans

[undy]

There's another potential cause, a very weak idle too. A very lean idle mixture could be easily "upset" by the increased alternator load trying to keep the battery up to snuff.

Dave

[RICK LAKE]

For Paw Let's start in the beginning. Do you know the Alt output?? Yes, No, maybe? You need an Alt that can keep all the electrical loads running and keep a min of 12.5 volts going to the battery at 1000 rpms. THE ALTENATOR is what powers all the loads once the motor is started. The battery is for staring the car and backup if the car idles for a long time with everything on,lights, cooling fans, blower motor, Msd module, Msd coil, electric fuel pump, etc. The batttery also absorbs the charging spikes from the ALT. What pulleys are you running? If they are not about 6" in diameter for the waterpump and crank pulley, they are TOO SMALL. The March system is underdriven and is good for racing and high rpm motors but not street driven low rpm cruiser. Here is some facts, MSD module draws about 16-20 amps, the coil draws about 6-10 amps, coolant fans, depending on how many from 10-30+ amps, electric fump pump 8-15 amps, Head lights and tail lights about 8-14 amps depending on what type, heater blower motor depending on speed, about 12-17 amps. With just the 6 thing a have here you are over most alt outputs at idle. An MSD system will not work below 10.4 volts. This is the steady drain on the system. Turning things on and off you are looking at spike loads of double to triple the running loads. This is why your car starts running rough. Not enough juice. A 100 amp min is the standard thing with normal pulleys. Most new car that are loaded are running 200 amp alts. Your playing with the timing is not helping. What is the CCA, cold cranking amps of the battery?? You should have something in the 800-1000 if possible. If you are going to idle the car for more than a minute or 2. Shut the motor off and just run the coolant fans. Lets a solid lifter motor run at idle is not good for the valve train IMO. Get the right pulleys for the car to start, make sure you have a large CCA battery, and replace the Alt with a min of 100 amp. A 140 would be better and cost about the same. Make sure the MSD system is hooked up directly to the battery for the red and black wires. This should help fix your problems. If you have any questions call me 732-254-3536 in the evening est time Rick Lake. Ps MAD Alt and PA Alt have real easy alts to swap into your car for plenty of charging. You may have to swap your amp gauge to a volt gauge with the power increase. There kits are 1 or 2 wire. Something to look into. Rick

[Hans-Olof Blom]

The current draw for a MSD 6AL unit is 1 Amp/1000rpm. At idle this means a current draw of about 1 Amp.

A standard alternator is enough for most Cobras.

[RICK LAKE]

Hans-Olof Blom Hans if you go to the MSD site and check out Q&A you need 5 amps and 10.2 volt min. This doesn't include the coil. Do you know how big the compasitors need to be to put out on an HVC that makes 80-100,000 volts with 1 amp. About the size of a paint can. I have been running an MSD system for 10+ years on the cobra and another 15 years on my Trans-am. Number have posted above are very close to the real world numbers. Rick L. Ps I think you are saying that with the addition of 1,000 rpms the amps need to run the system increase 1 amp. It's more like 2-3 per 1,000 Also a 60 amp Atl can't power a ERA cobra with all the power on at idle with an MSD system. Alt putout is about 35-38 amps at idle. Msd, lights, blower motor, and 3 cooling fans, are over the max. I know from racing the car. Rick L.

[For Paw]

Thanks for all the advice. Just to set the record straight, the wiring has been done with the best of breed components-everything from 0 gauge non-oxidising bat cables used in high end audio applications run directly to the Alt, ground run right to the block/starter, to all the ground straps one could think of to mig welded ground bolts on the chassis. I have had great advice from the best in the industry and have followed their advice and double checked to make sure that i have not missed anything. The carbs have been tuned within an inch of their miserable lives, and I am as close to the sweet spot as possible without going to a Dyno (These are going to be replaced by a Weber Stack system over the winter once I get this idle issue solved) So I have chased this on and off for over a year now and everything keeps pointing to the Alt. I guess MSD like any other manufacturer can goof every once in a while.

I have decided to order a new Reactor 100A alt to replace the MSD 105A I had. The main difference in the two is that the Reactor deliver full capacity at 1450 rpm vs MDS at 3000 and delivers more at 1000 rpm (idle for my engine) than any 1 wire on the market. I plan on measuring all the outputs once I get my parts and install them.

Rick, Alt output is 14.7. In one of my tests I unhooked the alt wire before starting and I did not have the problem when the fans kicked in. It might be something as simple as this Alt is malfunctioning. I have a 6.5 crank and larger water pump. I don't want to start changing Pulley ratios as this could start a chain reaction of water pump and cooling problems. The engine has been built to my specs by Southern Auto and they seem to know their stuff and have done these for many years now. This is a problem I have caused-I should have used their 65A alt supplied but i did not like the 3 wire system appearance and wanted something more advanced-that is pretty much where all this began. I did not realize that the 3000 rpm kick in on the MSD would be a problem. I am still holding that Alt ready to go if the Reactor does not work. All I need to do is get a voltage regulator or convert that to a one-wire. We'll see soon enough.

Randy

[McD00]

Originally Posted by For Paw

Thanks for all the advice. Just to set the record straight, the wiring has been done with the best of breed components-everything from 0 gauge non-oxidising bat cables used in high end audio applications run directly to the Alt, ground run right to the block/starter, to all the ground straps one could think of to mig welded ground bolts on the chassis. I have had great advice from the best in the industry and have followed their advice and double checked to make sure that i have not missed anything. The carbs have been tuned within an inch of their miserable lives, and I am as close to the sweet spot as possible without going to a Dyno (These are going to be replaced by a Weber Stack system over the winter once I get this idle issue solved) So I have chased this on and off for over a year now and everything keeps pointing to the Alt. I guess MSD like any other manufacturer can goof every once in a while.

I have decided to order a new Reactor 100A alt to replace the MSD 105A I had. The main difference in the two is that the Reactor deliver full capacity at 1450 rpm vs MDS at 3000 and delivers more at 1000 rpm (idle for my engine) than any 1 wire on the market. I plan on measuring all the outputs once I get my parts and install them.

Rick, Alt output is 14.7. In one of my tests I unhooked the alt wire before starting and I did not have the problem when the fans kicked in. It might be something as simple as this Alt is malfunctioning. I have a 6.5 crank and larger water pump. I don't want to start changing Pulley ratios as this could start a chain reaction of water pump and cooling problems. The engine has been built to my specs by Southern Auto and they seem to know their stuff and have done these for many years now. This is a problem I have caused-I should have used their 65A alt supplied but i did not like the 3 wire system appearance and wanted something more advanced-that is pretty much where all this began. I did not realize that the 3000 rpm kick in on the MSD would be a problem. I am still holding that Alt ready to go if the Reactor does not work. All I need to do is get a voltage regulator or convert that to a one-wire. We'll see soon enough.

Randy

Are you running a amp gauge? Sometimes they limit your current flow. I run a
regular ford 65 amp alternator and it powers my fans,lights and msd at the same time no problems. Sometimes all these fancy pants alternators are not the way to go.
Shelby just used a regular alternator and if it's good enough for him it's good enough for me.

Long live the Cobra!!

[undy]

nudder thing.....

Most fan manufacturers rate their fan CFMs above battery voltage. Spal, as listed here, rate theirs @ 13.0 volts. I believe Flex-a-Lite rates theirs even higher. If you have an "undersized" alternator that goes into discharge at idle then your electric fan isn't providing it's rated CFM. If you're driving the typical "cooling challenged" Cobra, that's not a good thing. With everything on my alternator provides a constant 14 volts, at the battery OR the fan. If your car's wiring "infrastructure" is also inadequate, which a LOT are, then the problem's compounded. With your car running, at idle, run a voltage test at the cooling fan. A lot of people would be suprised. With my Lone Star's painless harness and provided 65 amp alternator I was getting 10.2 volts to my cooling fan till I rewired the whole circuit.

Dave

http://www.spalusa.com/fans/automate.../1516-1517.pdf

[RICK LAKE]

For Paw Randy Please read the info on MAD alt site and PA performance on there site. Yes some alt don't putout alot of amps at idle or 1,000 rpms. Some one wire systems need a min of 2,000 rpms before they start to charge the car after startup. IMO this is bad for both the electric system and the motor. Cold oil that is thick having to turn higher rpms than should be needed for a cold start. This is why you need a high cca battery. To be honest, 14.7 is high voltage for any system unless you are running a 16.0 volt system, then you are low. This sounds like a weak cell battery in your car. You need to have the battery tested for CCA and load. Most Alt deliver max output by 1,500 rpms. This is nothing new. The voltage regulator controls the output anyway. I run a 70 amp alt with all the same things you are running without any problems. For high ampage systems you should switch over to a voltage gauge. You need to find out what the ampage rate is first. Pulleys on the motor to water pump should be 1-1. pulley ratio should be about 3-1 on the alt to the other pulleys. Rick L.

[Hans-Olof Blom]

Rick,

You are recommending a minimum of 100 Amps for the alternator and that 140 Amps would be lot better. Then you write that you are using a 70 Amps alternator?

I am using an MSD Digital-6 unit with a current draw of 0,7 Amps/1000rpm. The numbers for the MSD units are from MSD's specification. I assume that they know what they manufacture and sell. A minimum of 5 Amps is probably what is needed to be able to drive the car.

I have a standard 65 Amps Ford alternator which is what ERA recommends. I have no problems with the electrical system. Yes, the Amp-meter goes negative when my 3 cooling fans kicks in at idle. But that is one reason why I have a battery in the car.