MSD Ignition Questions
Thread Starter
Heel & Toe
Joined: Nov 2003
Posts: 22
Likes: 0
From: Youngstown OH
MSD Ignition Questions
I have recently rebuilt my 71 LT-1 motor. The major modifications were a higher lift (.489") and higher duration (248 advertised). The car has a freshly rebuilt, original, transistorized ignition system. Despite all carb tuning efforts (with assist from Lars), the motor seems to load up at idle and runs noticealby rich. Furthermore, the motor now prefers about 46 degrees of total timing. It's my belief that the high total timing number is a bandaid to cove for insufficient spark and spark duration.
For those who have MSD ignition systems I would like to ask whether or not upgrading to a modern ignition system improved idle characteristics, reduced sensitivity to rich/lean conditions, improved throttle response and overall performance.
Your comments would be appreciated.
For those who have MSD ignition systems I would like to ask whether or not upgrading to a modern ignition system improved idle characteristics, reduced sensitivity to rich/lean conditions, improved throttle response and overall performance.
Your comments would be appreciated.
Le Mans Master
Joined: Apr 2001
Posts: 5,941
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From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
Re: MSD Ignition Questions (SteelCitiesLT1)
I just put an MSD distributor and a Digital 6 box on my 71. Before that I had an HEI, points and a Pertronix 2. Out of everything I have tried the MSD is by far the best set up. The car starts quickly, and runs great. I believe the multiple sparks help take care of rich conditions I had at idle. I took the an expensive route costing around 600 dollars for everything, but I feel it was worth every penny now. Additionally, the MSD distributor is a tach drive so my original tach is working again.
Race Director
Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
Re: MSD Ignition Questions (Sigforty)
I just put an MSD distributor and a Digital 6 box on my 71. Before that I had an HEI, points and a Pertronix 2. Out of everything I have tried the MSD is by far the best set up. The car starts quickly, and runs great. I believe the multiple sparks help take care of rich conditions I had at idle. I took the an expensive route costing around 600 dollars for everything, but I feel it was worth every penny now. Additionally, the MSD distributor is a tach drive so my original tach is working again.
Race Director
Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
Re: MSD Ignition Questions (SteelCitiesLT1)
An unported source is a source on the carb that is located below the throttle plates (usually in front and below the front fuel bowl on a holley) and has vaccum all the time the eng is running, by using an unported source it will bump up your idle timing thus smoothing out your eng. An adjustable vac advance can is a worth while investment so you can tailor your vac adv curve to fit your engines need, it sounds like you are not running much initial adv if you are getting 46 total timing, what is your initial/base timing?
[Modified by Fevre, 4:01 PM 2/25/2004]
[Modified by Fevre, 4:01 PM 2/25/2004]
Thread Starter
Heel & Toe
Joined: Nov 2003
Posts: 22
Likes: 0
From: Youngstown OH
Re: MSD Ignition Questions (Fevre)
My intial timing is 22 degrees! The distributor has 24 degrees for a total timing number of 46 degrees. Seems pretty high to me but the motor does not lope when starting and there is no audible detonation under high engine loads. Loads up less at higher advance. with initial around 14-16 degrees (total around 38-40 degrees) idle is rough and motor loads up. I think the advance is covering insufficient buring of fuel
Thread Starter
Heel & Toe
Joined: Nov 2003
Posts: 22
Likes: 0
From: Youngstown OH
Re: MSD Ignition Questions (SteelCitiesLT1)
Regarding a ported source for Vac advance. I currently have the advance line running from a "T" on the front of the carb, below the float bowl. This line is shared with the choke pulloff and smog line.
Race Director
Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
Re: MSD Ignition Questions (SteelCitiesLT1)
22, that must be pretty hard on the starter. Sounds like you are not running vac adv since your are at 22 initial and assuming 24 mech for a total of 46, that is way to high for WOT, you might get some serious detonation without knowing it. This is where vac adv at idle is nice, you can drop the initial down to 10 or 12 then get 10 to 14 vac adv depending on the can for any where from 20 to 26 of idle adv.
I would contact Lars (forum member name) through his e-mail, he is the forum guru on dist/carbs, he will walk you through how to set up your timing to perfection.
Here is paper on it, it has his contact info in it:
https://www.corvetteforum.com/techti...=109&TopicID=3
I would contact Lars (forum member name) through his e-mail, he is the forum guru on dist/carbs, he will walk you through how to set up your timing to perfection.
Here is paper on it, it has his contact info in it:
https://www.corvetteforum.com/techti...=109&TopicID=3
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Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: MSD Ignition Questions (SteelCitiesLT1)
Go with digital. I like my Crane cams h-6R Multi spark, Mallory Unilite distributer, Crane coil, taylor 409 pro wires, Bosche 4 tip platinum plugs.
IMO - I can't tell the difference whether I have the box turned on or off. The idle is the same, throttle responce is the same, always fires right up. So I believe that a well tuned system doesn't need a multi spark. I really only have it for it's dial adjustable soft touch sequential rev limiters.
I had the MSD 6AL's before. The Crane box is smaller and can be taken out of the system in under 30 seconds if it fails. I could do it on a dark night without a flash light. The two water proof jacks in are a male and female. So you just pull them off the box and plug them together.
My first MSD died going down the road one day and after looking at everything I called around and a speed shop near where I was had one. So 2-3 hours later I was on the road again
IMO - I can't tell the difference whether I have the box turned on or off. The idle is the same, throttle responce is the same, always fires right up. So I believe that a well tuned system doesn't need a multi spark. I really only have it for it's dial adjustable soft touch sequential rev limiters.
I had the MSD 6AL's before. The Crane box is smaller and can be taken out of the system in under 30 seconds if it fails. I could do it on a dark night without a flash light. The two water proof jacks in are a male and female. So you just pull them off the box and plug them together.
My first MSD died going down the road one day and after looking at everything I called around and a speed shop near where I was had one. So 2-3 hours later I was on the road again
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: MSD Ignition Questions (SteelCitiesLT1)
Ok so you are running your vac adv at idle, go ahead and read Lars' paper, it is great info. A MSD box will def help smooth that idle out and according to some dyno tests Lars did it will actually gain you a few ponies!
Thread Starter
Heel & Toe
Joined: Nov 2003
Posts: 22
Likes: 0
From: Youngstown OH
Re: MSD Ignition Questions (Fevre)
Thanks a bunch. I have already contacted Lars via e-mail regarding my issues. I agree that I'm way too far advanced. furthermore, it appears that my fresh rebuilt motor has demands that can not be satisfied with my original transistorized ignition system. Off to Summit!!
Race Director
Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
Re: MSD Ignition Questions (SteelCitiesLT1)
Just to follow up with what George said (gkull) I have a Crane HI-6 on my formula and it is much smaller, digital, built in rev limiter and like he said can be by-passed by just switching the connectors as desc so it would be my choice as an add on, I already had the MSD box in the vette so decided to add the ProBillet dist since it looks so damn good. :)
Thread Starter
Heel & Toe
Joined: Nov 2003
Posts: 22
Likes: 0
From: Youngstown OH
Re: MSD Ignition Questions (Fevre)
I'm looking at the MSD "Corvette Pro-Billet Tach Drive" distributor. Has vac advance, adjustable mechanical and runs my tach. I will check out the Crane and Mallory systems.
Race Director
Joined: Dec 1999
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From: Forked River NJ
Re: MSD Ignition Questions (SteelCitiesLT1)
I am running a Crane HI6 box on my LT1 also. My cam is a 248 @.050 dur and my timing is set at 12 to 14 initial timing. With a total of 36. It sounds like some thing is wrong. Check to make sure your balancer has not slipped. That sounds like a lot of advance. I can idle my car for a long time and it never loads up. A good stock distributor will provide enough spark but the multi spark boxes do make it idle nice.
I have the stock dist. with a set of heavy duty points that triggers the box. Running a MSD coil. I also have an adjustable vacuum advance tha tis set to give me an additional 12 degrees but it is ported so I have no advance at idle.
[Modified by Gordonm, 5:17 PM 2/25/2004]
I have the stock dist. with a set of heavy duty points that triggers the box. Running a MSD coil. I also have an adjustable vacuum advance tha tis set to give me an additional 12 degrees but it is ported so I have no advance at idle.
[Modified by Gordonm, 5:17 PM 2/25/2004]
Race Director
Joined: Aug 1999
Posts: 18,126
Likes: 174
From: WI
Re: MSD Ignition Questions (SteelCitiesLT1)
My motor ran GREAT for years with a factory TI distributor a MSD box and MSD coil. ...redvetracr
PS: I do run a MSD distributor now because I wanted a dual pickup/dual box ignition.
PS: I do run a MSD distributor now because I wanted a dual pickup/dual box ignition.
Intermediate
Joined: Mar 2003
Posts: 37
Likes: 0
From: Youngstown OH
Re: MSD Ignition Questions (redvetracr)
redvetracr, I didn't know that the stock TI distributor is compatable with modern ignitions (MSD box and coil). Maybe I should give it a try. Where do you have the box mounted?
Race Director
Joined: Aug 1999
Posts: 18,126
Likes: 174
From: WI
Re: MSD Ignition Questions (SC71LT1)
SC, I do NOT have a stock floor pan and firewall but my boxes and coils (I have two) are inside the car in the area of the passengers foot well. Your TI distributor wires hook to the green and violet wires coming out of the box, white w/green stripe goes to the green and the all white goes to the violet. On the other side of the box red to ignition key, orange to coil + and black to coil -.
...redvetracr
...redvetracr
Instructor
Joined: Aug 2001
Posts: 120
Likes: 0
From: westmoreland n.h.
Re: MSD Ignition Questions (SC71LT1)
get the msd. setup. best thing i've done for the vette... :party: :party:
tach drive dist.. blaster2 coil, and 6al box with 8.5 mm wires...
dist. fits under ign. cover too..
[Modified by dash8, 4:36 PM 2/26/2004] :cheers:
[Modified by dash8, 4:37 PM 2/26/2004]
tach drive dist.. blaster2 coil, and 6al box with 8.5 mm wires...
dist. fits under ign. cover too..
[Modified by dash8, 4:36 PM 2/26/2004] :cheers:
[Modified by dash8, 4:37 PM 2/26/2004]
