MSD question
Thread Starter
Cruising
Joined: May 2005
Posts: 12
Likes: 0
MSD question
Installed an MSD 6A on '76 L48 auto. The car cruises nicely and WOT is improved BUT there is now a hesitation at take off unless I mash the pedal. Also before MSD install, the car would consistently chirp the tires at 1/2 throttle from a standing start. Now nothing. I certainly didn't expect to lose low RPM power with this ignition. I've never run into anything like this before. Installed MSD on an old Fairlane years ago and did not experience this problem. Any suggestions?
Thanks
Thanks
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
No way the MSD took away power. I believe at low rpm the MSD fires twice and as for 1/2 throttle chirping the tires again the MSD wouldn't loose power. Something else has changed. As for spark plug gap I just leave it the same as stock.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Originally Posted by rw131136
Sparks plugs were not removed or regapped. Nothing was changed. I expected low RPM improvement but for some reason this has not been the case.
Thread Starter
Cruising
Joined: May 2005
Posts: 12
Likes: 0
"A spark is a spark if it ignites the mixture."
Good point - IF it ignites the mixture. Standard induction ignition sparks are longer in duration yet less intense than a CD generated spark.
The mulitple spark function is supposed to make up for the shorter duration spark of a CD and that is why I can't figure out why I'm getting these kind of results.
I wrote MSD through their web site. Hopefully they can provide some assistance. If not I'll just take the thing off. 30 years ago I didn't mind giving up some bottom end power for more high RPM power, but now I just want a nice responsive street motor.
Good point - IF it ignites the mixture. Standard induction ignition sparks are longer in duration yet less intense than a CD generated spark.
The mulitple spark function is supposed to make up for the shorter duration spark of a CD and that is why I can't figure out why I'm getting these kind of results.
I wrote MSD through their web site. Hopefully they can provide some assistance. If not I'll just take the thing off. 30 years ago I didn't mind giving up some bottom end power for more high RPM power, but now I just want a nice responsive street motor.
Pro
Joined: Jun 2005
Posts: 660
Likes: 4
From: Fredericksburg VA
when installing an MSD it is possible to inadvertently bump the distributor and adjust the timing if only a few degrees. This will and can cause the symptoms that you are describing. Try to advance the timing 2 degrees at a time and see if the problem clears up. Use your head and don’t advance to far though. no more than 6 or 8 degrees past stock.
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Team Owner
Joined: Jun 2004
Posts: 20,216
Likes: 4
From: Smile, it's just the internet.
I have a digital 6, so I may be barking up the wrong tree. On mine, there are controls for "start retard" It can retard timing 20 degrees below 800 rpm. Any chance your idle is below 800 and your MSD is retarding the timing?
Le Mans Master
Joined: Jun 2003
Posts: 5,446
Likes: 2
From: Not Correctly Restored Stingray Fla.
Change plug gap to .045 and advance the timing 1 or 2 degrees. That should solve your problem.
In 1977 (close to when MSD first came out), I put a 6A box in my stock '71 Z-28 w/LT-1. I was one of the only mods that I actually felt a difference (for the better) right away. It was a much better pedal response.
In 1977 (close to when MSD first came out), I put a 6A box in my stock '71 Z-28 w/LT-1. I was one of the only mods that I actually felt a difference (for the better) right away. It was a much better pedal response.
Last edited by LOTAHP; Jun 14, 2005 at 01:41 PM.
Thread Starter
Cruising
Joined: May 2005
Posts: 12
Likes: 0
I checked the timing and it had not changed. Dist cap and rotor were replaced about a month ago. Wires are Moroso Blue Max. Plugs are gapped at factory spec .045
I think I'm going to put the HEI back in. If the problem goes away I'll know it's the box.
Thanks for all your suggestions
I think I'm going to put the HEI back in. If the problem goes away I'll know it's the box.
Thanks for all your suggestions
Le Mans Master
Joined: Oct 2002
Posts: 5,714
Likes: 6
From: Silver City NM
St. Jude Donor '05-'07
Originally Posted by rw131136
I checked the timing and it had not changed. Dist cap and rotor were replaced about a month ago. Wires are Moroso Blue Max. Plugs are gapped at factory spec .045
I think I'm going to put the HEI back in. If the problem goes away I'll know it's the box.
Thanks for all your suggestions
I think I'm going to put the HEI back in. If the problem goes away I'll know it's the box.
Thanks for all your suggestions
Dep
Thread Starter
Cruising
Joined: May 2005
Posts: 12
Likes: 0
HEI is back in and the low RPM power has returned with no more hesitation or stumble on take off 
I guess this was an expensive lesson learned. The HEI isn't as weak as all the aftermarket ignition companies would have us believe.
I guess this was an expensive lesson learned. The HEI isn't as weak as all the aftermarket ignition companies would have us believe.
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
HEI is a fine system unless you want to run high RPM. then they start to loose it. But an after market module can fix that.
If I were to do it again I would use a modded HEI...
If I were to do it again I would use a modded HEI...