MSD 6A?? Worth it?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

67chevemall · 01-11-2005, 10:11 PM

I was thinking of getting a better ign. system and was wondering if the
MSD 6A is a good upgrade?
How much more spark is it? Does it just install with power from the
batt. and the Ign. wire like a big relay!

**'70_402** · 01-11-2005, 10:16 PM

from what i have read and understand is that you should only need a ign box like that if you are racing, regularly get you motor above or around 6500 to 9000 rpms, and have very high compression ratios. other than that if this is a street truck that sees some race track time. then a good high performance hei will work just as well. you are probally not going to see any hp gains just from adding this.

I once was plagued with this same question.

Rick

68w/sbc406 · 01-11-2005, 10:17 PM

i got a 6AL and it was easy to wire up. mine had a wire diagram on the back of it. you used on set if you had a MSD dizzy and you used a different set if you didnt.
EDIT: i went from a L6 w/points to a V8 with MSD, i didnt really notice a MPG increase

my new 72 · 01-11-2005, 10:28 PM

An MSD 6AL box is worth it. Even if you are just looking for a bit better mileage. Before I got mine I had an HEI and the difference on the little 305 that was in the truck at the time. With the 385, it definitely is earning it's keep.

Fred T · 01-11-2005, 11:51 PM

On my friends 52 with a hot 261 (I-6) he started with a Uni-lite distributor. Later added the MSD-6 box. Made a huge difference in the idle smoothness and added a lot of power to the low end. The only downside is his electricity consumption at high rpm. With a 60 amp alternator he had to switch to an Optima battery to have more amps available at short notice.

We were able to get his idle down to 600 rpm with a full race cam. I've never been able to get that low of an idle with a cam that hot.

*dtlilly* · 01-12-2005, 03:12 AM

I had one in my old GMC with a built 355. Was mounted where the glove box liner would go to keep it dry and out of view.

SweetandLong68 · 01-12-2005, 05:25 AM

Definetly a good upgrade....

The only thing is I wouldn't skimp and just get the 6A....Go ahead and get the 6AL. It might save your motor one day. And it is always good to have a rev limiter.

I like Mallory's Uni-lite distributors over MSDs just because of the way that they are made...One using magnets and the other using LEDs.

lata
CHRIS

4x4Poet · 01-12-2005, 10:20 AM

MSD boxes work well and I, too, used to be on the solely capacitive discharge bandwagon for street engines that weren't raced or otherwise run above 6000rpm. I used a few Jacobs systems. But for street engines, I now think Pertronix has it right with their Second Strike box that adds a CD spark to the inductive, long-duration spark that is superior for low-rpm combustion. From their website:

"Second Strike is the only ignition system to provide a powerful second spark throughout the entire RPM range, unlike other multiple spark discharge systems, which typically drop off to one spark at about 3000 RPM. This micro controller based ignition supplements most inductive type systems (points, GM HEI, Ford TFI and Duraspark, Ignitor and Ignitor II) with a powerful capacitive discharge second spark resulting in more complete combustion of the fuel/air mixture. Increased burn time at very high RPM levels also reduces misfires resulting in more peak horsepower and torque...."

CD only systems must use multiple sparks at low rpm to compensate for the short, albeit hot, duration of CD sparks. Even though the CD spark is hotter than an inductive system's spark, given the same coil output, a single CD spark cannot effectively burn the A/F mixture thoroughly at low rpm when combustion chamber process is slower and cooler than at high rpms when CD sparks shine. At low rpms, the inductive system's long-duration single sparks are superior, given a high quality inductive system. High rpms get two sparks (inductive & CD) instead of one CD spark most CD systems provide after 3k rpm. With the Pertronix Second Strike, you get the best of both ignition system types from idle up to the rev limit. (High rpm race only engines no doubt use a higher quality CD spark system that can provide multiple sparks at any rpm. More $$ too).

An inability to set a low idle rpm on inductive systems probably has more to do with the system's condition such poor quality (including low voltage coils), worn, or damaged ignition wires, coil, points, cap, rotor, and maybe spark plugs. If you install a CD system and notice an improvement at low rpms then you probably just proved that the original system was worn, damaged, or an inferior type of inductive ignition system for which the multiple CD sparks compensated.

I'm still learning, but I think I can make the following claim as to which systems would be best (excepting $1k up race systems):
1. DUI (HEI) distributor tuned to specific engine with Pertonix Second Strike.
2. HEI with high voltage coil and Pertronix Second Strike.
3. Pertronix Flamethrower Distributor with Second Strike.
4. 69-74 dist with Pertronix II, Flamethrower II coil, and Second Strike.

And, as usual, I'd like to recommend the perusal of the first three articles on Magnecor's website. Very informative regarding the ongoing high perf ignition wire marketing scams.

I strongly encourage dissent. I might learn something.

67chevemall · 01-12-2005, 03:26 PM

Thanks guys! I've been babying my motor and the plugs are always carboned when changing them. So I thought maybe more spark might help the engine last longer!
Or maybe I should start stomping on it more!~

SweetandLong68 · 01-13-2005, 07:17 PM

I vote for no more babying of the motor!

Run it! Clean out that carbon! hahaha

lata
CHRIS

71Rat · 01-13-2005, 07:28 PM

go with MSD i got a mallory box, the thing has been headaces since i got it..... well this is the second one the first one didnt work for anything...complete junk.. now this one wont start the truck and when i am driving just randomly shut the truck off.... i have checked everything like 10 times, it is the box..... i am saving for an MSD 6AL..... go MSD and never have to replace it...

Rat

SweetandLong68 · 01-13-2005, 07:38 PM

Quote:

Originally Posted by 71Rat

go with MSD i got a mallory box, the thing has been headaces since i got it..... well this is the second one the first one didnt work for anything...complete junk.. now this one wont start the truck and when i am driving just randomly shut the truck off.... i have checked everything like 10 times, it is the box..... i am saving for an MSD 6AL..... go MSD and never have to replace it...

Rat

Did you use a Mallory Power Filter? It is a MUST when using the powerful Mallory Ignitions...

Here is a link and a pic to show you what I am talking about...

http://www.jegs.com/cgi-bin/ncommerc...27&prmenbr=361

lata
CHRIS

01-11-2005, 10:11 PM	#1
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	MSD 6A?? Worth it?? I was thinking of getting a better ign. system and was wondering if the MSD 6A is a good upgrade? How much more spark is it? Does it just install with power from the batt. and the Ign. wire like a big relay! __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

01-11-2005, 10:16 PM	#2
'70_402 Senior Member Join Date: Dec 2003 Location: Pampa, Texas Posts: 1,553	from what i have read and understand is that you should only need a ign box like that if you are racing, regularly get you motor above or around 6500 to 9000 rpms, and have very high compression ratios. other than that if this is a street truck that sees some race track time. then a good high performance hei will work just as well. you are probally not going to see any hp gains just from adding this. I once was plagued with this same question. Rick __________________ https://www.ebay.com/itm/29620574751...mis&media=COPY

01-11-2005, 10:17 PM	#3
68w/sbc406 Got Light Emitting Diode? Join Date: Apr 2004 Location: Newberg, OR Posts: 2,485	i got a 6AL and it was easy to wire up. mine had a wire diagram on the back of it. you used on set if you had a MSD dizzy and you used a different set if you didnt. EDIT: i went from a L6 w/points to a V8 with MSD, i didnt really notice a MPG increase __________________ 1968 1/2 ton 2wd lwb 6 lug disc and bags up front. Next c notch and rear bags '02 Chevy Silverado LT ext cab short bed 2WD 5/7 drop on 22's(the family car) 1993 Cherokee work ride/weekend wheeler Last edited by 68w/sbc406; 01-11-2005 at 10:31 PM. Reason: mo info

01-11-2005, 10:28 PM	#4
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	An MSD 6AL box is worth it. Even if you are just looking for a bit better mileage. Before I got mine I had an HEI and the difference on the little 305 that was in the truck at the time. With the 385, it definitely is earning it's keep. __________________ I'm going to Law School, wanna debate? It's good practice.

01-11-2005, 11:51 PM	#5
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	On my friends 52 with a hot 261 (I-6) he started with a Uni-lite distributor. Later added the MSD-6 box. Made a huge difference in the idle smoothness and added a lot of power to the low end. The only downside is his electricity consumption at high rpm. With a 60 amp alternator he had to switch to an Optima battery to have more amps available at short notice. We were able to get his idle down to 600 rpm with a full race cam. I've never been able to get that low of an idle with a cam that hot. __________________ Fred There is no such thing as too much cam...just not enough engine.

01-12-2005, 03:12 AM	#6
dtlilly Account Suspended Join Date: Jan 2003 Location: Shadow of Lambeau Field Posts: 5,597	I had one in my old GMC with a built 355. Was mounted where the glove box liner would go to keep it dry and out of view.

01-12-2005, 05:25 AM	#7
SweetandLong68 Your UncleBen Join Date: Dec 2002 Location: Indian Trail, NC Posts: 590	Definetly a good upgrade.... The only thing is I wouldn't skimp and just get the 6A....Go ahead and get the 6AL. It might save your motor one day. And it is always good to have a rev limiter. I like Mallory's Uni-lite distributors over MSDs just because of the way that they are made...One using magnets and the other using LEDs. lata CHRIS __________________ 68 C10 shortbed -- Street/Strip

01-12-2005, 10:20 AM	#8
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	MSD boxes work well and I, too, used to be on the solely capacitive discharge bandwagon for street engines that weren't raced or otherwise run above 6000rpm. I used a few Jacobs systems. But for street engines, I now think Pertronix has it right with their Second Strike box that adds a CD spark to the inductive, long-duration spark that is superior for low-rpm combustion. From their website: "Second Strike is the only ignition system to provide a powerful second spark throughout the entire RPM range, unlike other multiple spark discharge systems, which typically drop off to one spark at about 3000 RPM. This micro controller based ignition supplements most inductive type systems (points, GM HEI, Ford TFI and Duraspark, Ignitor and Ignitor II) with a powerful capacitive discharge second spark resulting in more complete combustion of the fuel/air mixture. Increased burn time at very high RPM levels also reduces misfires resulting in more peak horsepower and torque...." CD only systems must use multiple sparks at low rpm to compensate for the short, albeit hot, duration of CD sparks. Even though the CD spark is hotter than an inductive system's spark, given the same coil output, a single CD spark cannot effectively burn the A/F mixture thoroughly at low rpm when combustion chamber process is slower and cooler than at high rpms when CD sparks shine. At low rpms, the inductive system's long-duration single sparks are superior, given a high quality inductive system. High rpms get two sparks (inductive & CD) instead of one CD spark most CD systems provide after 3k rpm. With the Pertronix Second Strike, you get the best of both ignition system types from idle up to the rev limit. (High rpm race only engines no doubt use a higher quality CD spark system that can provide multiple sparks at any rpm. More $$ too). An inability to set a low idle rpm on inductive systems probably has more to do with the system's condition such poor quality (including low voltage coils), worn, or damaged ignition wires, coil, points, cap, rotor, and maybe spark plugs. If you install a CD system and notice an improvement at low rpms then you probably just proved that the original system was worn, damaged, or an inferior type of inductive ignition system for which the multiple CD sparks compensated. I'm still learning, but I think I can make the following claim as to which systems would be best (excepting $1k up race systems): 1. DUI (HEI) distributor tuned to specific engine with Pertonix Second Strike. 2. HEI with high voltage coil and Pertronix Second Strike. 3. Pertronix Flamethrower Distributor with Second Strike. 4. 69-74 dist with Pertronix II, Flamethrower II coil, and Second Strike. And, as usual, I'd like to recommend the perusal of the first three articles on Magnecor's website. Very informative regarding the ongoing high perf ignition wire marketing scams. I strongly encourage dissent. I might learn something. __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup. Last edited by 4x4Poet; 01-12-2005 at 10:33 AM.

01-12-2005, 03:26 PM	#9
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	Thanks guys! I've been babying my motor and the plugs are always carboned when changing them. So I thought maybe more spark might help the engine last longer! Or maybe I should start stomping on it more!~ __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

01-13-2005, 07:17 PM	#10
SweetandLong68 Your UncleBen Join Date: Dec 2002 Location: Indian Trail, NC Posts: 590	I vote for no more babying of the motor! Run it! Clean out that carbon! hahaha lata CHRIS __________________ 68 C10 shortbed -- Street/Strip

01-13-2005, 07:28 PM	#11
71Rat ran out of money Join Date: Apr 2003 Location: northern, NJ Posts: 925	go with MSD i got a mallory box, the thing has been headaces since i got it..... well this is the second one the first one didnt work for anything...complete junk.. now this one wont start the truck and when i am driving just randomly shut the truck off.... i have checked everything like 10 times, it is the box..... i am saving for an MSD 6AL..... go MSD and never have to replace it... Rat __________________ Modify everything, leave nothing alone!~



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