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BillyG,
Thanks for the kind comments. I agree with many of your statements, & yes, if you fitted a MSD 6AL or equivalent 'box' to a car that had points ign, you will very likely notice improvements such as easier starting, idle quality etc.
My point [ pardon the pun ] was & is: that if the engine had HEI & it was replaced with an MSD box, there would be NO difference in all but the highest output engines.........except for a lighter wallet. Also, the 'box' ign systems add more components & connection points that can fail, so there is also a reliability factor involved.
Now, some of the elec ign conversion kits that retain the stock coil & ballast resistor/resistance wire really just provide breakerless triggering, but no increase in spark energy like the HEI does. So replacing one of these with the MSD 6XX might well provide an improvement you can feel. But overall, the HEI is hard to beat for cost, reliability & performance.
Much easier to tailor an advance curve on the MSD distributor than on an HEI plus the HEI is a space eater. (and ugly)
 

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I've read the literature that came with the 6AL2 and have a question about
the coil that will work with the unit. MSD says a standard stock type coil
is all that is needed.

Reading between the lines it seems that using an excellent coil will ruin
the MSD unit. That is if you have an ultra performance coil that is great
at performing the inductive spark it might not be so good with a
capacitance discharge system.

Any one have experience regarding this issue?

Your thoughts are appreciated.

Cheers
I use the 6al and the msd 8202 coil with success.
 

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The bigger cap diam of HEI might be 'ugly', but the wider segment spacing reduces the chance of crossfire inside the cap, as a consequence of the increased spark energy of HEI over the small cap points dist. Ford went to the bigger cap also with their elec ign systems, even though there was no coil-in-cap. Unless Ford had excess cash they wanted to get rid off, there was no engineering reason to tool up for the bigger cap other than to reduce crossfire. These elec ign systems can & do run 0.060" plug gaps & this also is a good reason to have a larger cap with larger segment spacing, to reduce crossfire.

Coils with MSD CD igns.

You can use an inductive coil with CD, but you CANNOT use a dedicated CD ign coil with inductive igns. To get the best out of a CD ign, it is best to use the recommended coil.
 

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The bigger cap diam of HEI might be 'ugly', but the wider segment spacing reduces the chance of crossfire inside the cap, as a consequence of the increased spark energy of HEI over the small cap points dist. Ford went to the bigger cap also with their elec ign systems, even though there was no coil-in-cap. Unless Ford had excess cash they wanted to get rid off, there was no engineering reason to tool up for the bigger cap other than to reduce crossfire. These elec ign systems can & do run 0.060" plug gaps & this also is a good reason to have a larger cap with larger segment spacing, to reduce crossfire.

Coils with MSD CD igns.

You can use an inductive coil with CD, but you CANNOT use a dedicated CD ign coil with inductive igns. To get the best out of a CD ign, it is best to use the recommended coil.
HEI is still ugly. The standard chevy cap diameter (non HEI) is still used on many very very quick cars. In some instances the large cap is preferred and MSD has the cap a dapt for those situations. Then there are crank triggers. Lol
 

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I have a blaster ss 8207 coil with my msd 6-al2 box like I said earlier seven years and thousands of street miles still going strong. Personaly I wouldnt run wider than .045 gap with a HEI or msd 6 box. Theres a chart showing wich coil that will work with a msd box.
http://documents.msdperformance.com/techlibrary_coil_compability.pdf

I have got electric shocks from points, HEI and a msd 6-al box and I can say that the shock from the msd box was worse than what you get from 230v wall socket like we have here in Sweden and the HEI wasnt even close to the msd so Im convinced a msd box puts out a stronger spark than a HEI and my small cap msd distributor #8361 havent had any problems with crossfire. That said a HEI is still hard to beat especially for the money.
 

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I have got electric shocks from points, HEI and a msd 6-al box and I can say that the shock from the msd box was worse than what you get from 230v wall socket like we have here in Sweden and the HEI wasnt even close to the msd so Im convinced a msd box puts out a stronger spark than a HEI.
Ha Ha Ha...that's one heck of a way to perform a spark/current test Marcus.Way to take one for the team. I love it :D that IS kinda interesting though :thumbsup: Anyway thanks for that MSD chart. Awhile back, I purchased the MSD Blaster HVC II coil for use with my MSD 6 box, but I haven't installed it yet. I'm no electronics expert by any means. This coil is a little hefty in the price tag, and I wouldn't be quick to make the claim that their HVC II coil is even worth the extra money I paid for it. But I think that it has a little more output than the standard MSD coils do, and it is the number one recommended coil for the MSD 6 boxes(which the MSD chart that Marcus posted the link to reflects).


Geoff can correct me on that if he knows differently. When it comes to the electronic technical details, it sounds like his knowledge surpasses mine in that area. All I know is that the MSD 6 boxes have always made a very noticeable difference in the operation of my hi-perf street driven cars with carbs. But we don't need to re-visit that debate as far as I'm concerned. I just chimed in here again due to the post from Marcus (thanks). Here's that coil in the pic (& link) below...

https://www.summitracing.com/parts/msd-8253

 

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Ha Ha Ha...that's one heck of a way to perform a spark/current test Marcus.Way to take one for the team. I love it :D that IS kinda interesting though :thumbsup: Anyway thanks for that MSD chart. Awhile back, I purchased the MSD Blaster HVC II coil for use with my MSD 6 box, but I haven't installed it yet. I'm no electronics expert by any means. This coil is a little hefty in the price tag, and I wouldn't be quick to make the claim that their HVC II coil is even worth the extra money I paid for it. But I think that it has a little more output than the standard MSD coils do, and it is the number one recommended coil for the MSD 6 boxes(which the MSD chart that Marcus posted the link to reflects).


Geoff can correct me on that if he knows differently. When it comes to the electronic technical details, it sounds like his knowledge surpasses mine in that area. All I know is that the MSD 6 boxes have always made a very noticeable difference in the operation of my hi-perf street driven cars with carbs. But we don't need to re-visit that debate as far as I'm concerned. I just chimed in here again due to the post from Marcus (thanks). Here's that coil below...


LOL Im no expert either maybe thats why I have performed the test :D
Stupid things happen and I have done my share :D
When I performed the msd test I got stuck into to the coil wire and had it come loose all I can say is that Im more careful now.
 

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Have a stock SS 396 with Rochester 4bbl, thinking of installing an MSD 6AL Ignition Control Unit, will I notice better performance?
No. Not worth it especially with the new stuff.
 

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LOL Im no expert either maybe thats why I have performed the test :D
Stupid things happen and I have done my share :D
When I performed the msd test I got stuck into to the coil wire and had it come loose all I can say is that Im more careful now.
WARNING!! OFF-TOPIC POST HERE....move on to the next post if you're looking for technical info;)

....Pardon me for the digression, but that reminds me of when I was in school, our science teacher brought some type of very old generator that had a hand crank and a handle on it with a light bulb attached. I don't know where she found such a thing, but the faster the hand crank was turned, the brighter the light bulb lit up.

So ofcourse most of the boys in our class (myself included) lined up to see how fast they can crank the handle and how bright they can get that light to glow. I don't remember any of the girls being all that interested in it,( Kinda funny how that works, eh?)

Anyway, there were two terminals on the generator. the whole apparatus was mounted on a piece of plywood (or perhaps it was metal, I dunno, it was a long time ago) and boys being boys many of us found that if we placed our finger on the one terminal while our buddy was cranking the trigger, it gave you a mild tingling sensation through your hand which intensified as the crank was turned faster and faster by your eager and willing male classmate.

It became a game among us boys in that classroom to challenge each other to see who can keep their finger on that terminal the longest while the crank handle was being turned furiously by a willing buddy before that tingling sensation became so intense that you just had to pull away. :D

Well after this thing being in the classroom for a week or so, apparently someone must have gotten the idea to place his finger on the other terminal that nobody had messed with prior to that since we all were under the assumption that both terminals had the same amperage/same current flowing to them.

Who ever it was that made this brilliant discovery kept it to himself so it can then be used as a prank on his fellow classmates. :D All I can tell you for certain is I was one of those who found out the hard way that the other terminal on this contraption had considerably MORE current flowing to it when the crank handle was turned, (you can see where this is going, right?)....

One day a "friend" of mine says to me "Hey Billy, instead of puting your finger on this terminal that we've been toying around with, try placing it on the OTHER terminal." :D So being the adventurous kid that I was, I took his suggestion.... as I went to touch the OTHER terminal on this weird machine that we had been toying around with (when the teacher wasn't looking) he says to me "wait a second, first let me crank it up" and he then proceeded to turn that crank handle with an intensity that would've made an Olympic cyclist proud, (that right there should've gave me a hint what was about to happen) and stupid me didn't bother to stop and think, but instead, I just proceeded to place my finger onto that OTHER terminal thinking that it would be the same experience that I had been having all of that week as I did with the other more familiar terminal.

WRONG!!!! I touched that thing, and WHAMMO!!!! I was hit with so much electrical current that it literally felt like a huge fist hitting me HARD right into my chest!!! I mean I did NOT even feel anything on my finger nor on my hand, nor even up my arm at all. The shock wave went immediately and directly right to my chest. I had never felt anything like it. It almost knocked me off my feet! The kid manning the crank handle immediately burst out in histaric laughter, as he took his hand off of the crank handle (what a nice kid, eh?). Sorry for this long off-topic post. I just had to share.;)

In all honestly, I really don't remember if I ever went near that thing again, or if I followed suit by playing that same prank on other classmates who had not yet heard about that OTHER mysterious terminal that none of us had previously known about. What a science class that was. :D
 

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As I said in post #23, CD coils should not be used with ind ign .

The HVC coil that Billy posted a photo of looks like the 8253 or the 8261. Their prim/sec resistances are 0.16 ohm/630 ohm & 0.016 ohm/30 ohm. The 8261 is for use with the higher output MSD 7 series & puts out a 2 amp spark versus 0.45 amp for the 8253.

A coil for inductive ign typically has a pri resistance of 0.3-0.6 ohm, certainly no less than 0.3 ohms, & the secondary is several thousand ohms. Using one of these coils with CD ign will reduce the spark current & the lost energy gets converted to heating of the coil from the excessive resistance of the coil windings.
 

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Thank's for posting that list Marcus aka Malibu 22 64.

I think mine will work.

Any of you gents using the MSD boxes that interface to the comptuer?
or that are programmable?

While I'm not so interested in the programming aspect of it,
but as long as i'm buying a new box (I haven't installed the 6AL-2 yet)
for a little bit more money it's supposted to have some memory or
recall.

So do we go with the compute rinterface job for data logging?
or spend way more money on a stand alone data log unit
and devices, etc?

Thoughts? Comments? Experience?

Cheers,

USMC_Spike
 

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No. Not worth it especially with the new stuff.
@Chris, what is this NEW stuff you talked about?
The HVC coil that Billy posted a photo of looks like the 8253 or the 8261. Their prim/sec resistances are 0.16 ohm/630 ohm & 0.016 ohm/30 ohm. The 8261 is for use with the higher output MSD 7 series & puts out a 2 amp spark versus 0.45 amp for the 8253.

A coil for inductive ign typically has a pri resistance of 0.3-0.6 ohm, certainly no less than 0.3 ohms, & the secondary is several thousand ohms. Using one of these coils with CD ign will reduce the spark current & the lost energy gets converted to heating of the coil from the excessive resistance of the coil windings.
@GTO, this is all good info. I'll go back through the coils that I have
and take some measurements.

@Whom-ever posted the link from Dr. Holden with his research papers discussing ignitions and coils thank you very much.

@Everyman, My goal is to do some testing of what I have
using Dr.Holden's method--outlined in the Appendix to "CAPACITIVE DISCHARGE IGNITION and MAGNETIC DISCHARGE IGNITION.

I'll try to keep y'all posted about what I find out too.

Cheers,
 

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As I said in post #23, CD coils should not be used with ind ign .

The HVC coil that Billy posted a photo of looks like the 8253 or the 8261. Their prim/sec resistances are 0.16 ohm/630 ohm & 0.016 ohm/30 ohm. The 8261 is for use with the higher output MSD 7 series & puts out a 2 amp spark versus 0.45 amp for the 8253.

A coil for inductive ign typically has a pri resistance of 0.3-0.6 ohm, certainly no less than 0.3 ohms, & the secondary is several thousand ohms. Using one of these coils with CD ign will reduce the spark current & the lost energy gets converted to heating of the coil from the excessive resistance of the coil windings.
OK Geoff, so to be clear on this, what you're saying is that there's very good reason why that coil that I posted a pic of which has the blue case, (the MSD 8253 "HVC II" coil ) is the number one recommended coil for the MSD 6 boxes, since it will work much better with those units. Am I getting this right? That is a sincere question on my part Geoff. Thanks
 

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Some of all this is absolutely hilarious. I see this stuff EVERY day fixing the same for a lot of people.

The biggest problems an MSD box has, is not inside itself, it is the coil used. The MSD Blaster series of coils used to be just plain top notch when they were made in Andover, Indiana, then, Blaster coil production went to Juarez, Mexico, just across the river from MSD in El Paso, which gave those Blaster coils 70 percent average coil failures and problems, then now, made in China.

Anything Blaster that ISN'T made in USA, JUNK. They layer short, overloading both MSD boxes, AND HEI modules to failure. The main problem, the layer insulation degrades and then falls away from the windings, causing a "layer short", which changes the loading to and of the HEI, and/or other outside "box" to failure.

The next comedy show is "the large cap HEI was developed to combat spark scatter and over fire", YUP, heard all that, not even close. Anyone ever see the predecessor to the large HEI? It was, and is called the "unitized", and is built on a point base size body, small cap, with coil in cap. Module is outside the body. Anybody ever see an MSD distributor and cap" They are the SAME diameter as a stock GM window style point distributor and cap, and they have no cross, nor over fire issues, even when the significantly stronger capacitor discharge systems fire inside them.

Now, the large cap, with coil in cap was designed to have all the components in one package, and from the Unitized before it, the actual size of the body was too small, so, larger diameter allowed the module to go inside the cap, along with the coil also in the cap. And, this was done mostly for emissions regulations, as back then, the EPA was cracking down on tailpipe emissions, and that meant all systems had to go 50K miles WITHOUT ANY MAINTENANCE, AND/OR CHANGES OF ANY KIND.

How do I know all this? Well, it seems I worked at Chevrolet Skunk Works then, and on both the Unitized, AND large cap HEI development, and now, I am still involved in the ignition system business, have been for 4 plus decades.

Like I said, hilarious.
 

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The biggest problems an MSD box has, (snippage) made in China.

EFI (snippage) meant all systems had to go 50K miles WITHOUT ANY MAINTENANCE, AND/OR CHANGES OF ANY KIND.(snip) Chevrolet Skunk Works (snip)I am still involved in the ignition system business, have been for 4 plus decades.
@Dave Ray , me thinks you are the guy I need to talk
with about ignition, as you are the learned one.

I presume that the MSD Box works fine with a
good USA Made coil? What's a good Np/Ns ratio?
Measuring the primary tap what do we want to see?
for MSD?
for HEI?
for MDI?

Have you suggestions as best method for measuring
secondary resistance? Inductance?
Suggestions for measuring leakage Inductance?

I know it might be a lot to ask for, but I'm all ears
and having issues trying to separate out the
leakage Inductance from the Inductance
measurements as I run up against the coils
resistance. In one of my tests, I've located
the resonant frequency on the old Accell
super coil, 17.5kHz - 18kHz.

When I went back through it for scheisse and grins,
I looked into the THD numbers to see what the
residual harmonics looked like, as shown:
-58dB +-2 @ f
-63dB +-2 @2f
-70dB +-2 @3f
-80dB +-2 @4f
-52dB +-2 @5f
I suppos I could inject a 88.75kHz signal
into it and see what the harmonics look
like above that...but correlating it back
to the fundamental could be tricky.

If I understand things correctly, the next
resonant frequency should be somewhere in
the range of 330kHz to 400kHz, but I haven't
verified that yet. These resonances play havoc
when trying to identify the correct turns ratio.

This is in the area of applied physics as the
EE texts and most automotive texts don't cover
it.

If you have any thoughts about this I would
enjoy investigating it further. We could clear
up some TC misconceptions regarding things.

BTW, where you were with the General? Down at
12 Mile? Milford? Goleta?


Cheers,
 

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So Dave, do tell us why Ford tooled up & spent money on a bigger dist cap they didn't need because their system does have the cap-in-coil.
 

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GM tech info on the introduction of HEI:

"The size of the dist was increased due to the wide spacing that MUST exist between the dist inserts to prevent high voltage arc over. A wider spacing was also needed between the cap inserts & the dist housing to prevent arc-over & leakage to ground.
The higher voltage output of the HEI system reqd new insulation materials. To prevent ign failure due to carbon tracking tracking, a special material is used for the dist cap & rotor."

Nothing hilarious about that...
 

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Thank's for posting that list Marcus aka Malibu 22 64.

I think mine will work.

Any of you gents using the MSD boxes that interface to the comptuer?
or that are programmable?

While I'm not so interested in the programming aspect of it,
but as long as i'm buying a new box (I haven't installed the 6AL-2 yet)
for a little bit more money it's supposted to have some memory or
recall.

So do we go with the compute rinterface job for data logging?
or spend way more money on a stand alone data log unit
and devices, etc?

Thoughts? Comments? Experience?

Cheers,

USMC_Spike
I have a 6230 6al digital something that is going in with my new motor. Will be a lot easier to deal with the nitrous tuning.
 
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