[Lugnut79]

I recently upgraded from an old Accel BEI ignition to an MSD 6al with pro billet distributor. I'm running the same plugs I did with the BEI and the same fuel mixture 50/50 93 octane and Cam2 I ran with the BEI. The Engine has not been touched since the ignition upgrade and is still 12:1. My problem is I'm detonating something fierce. I'm running the same timing as I did with the BEI as well. 38* total. Do I need to switch to a cooler plug? The ones now have prob 10 miles on them and the ceramic around the electrode is starting to fall apart. Needless to say its not getting driven again until its fixed. What gives? Is the MSD that much of a hotter spark then the old one?

 

[stupesnova]

If I remember correctly you have to change the gap on the plugs with the MSD set up. Go back and read the directions it should tell you what the gap should be based on your CR.

 

[bowtie0069]

You can run the same gap with an MSD as you do with anything else. I race my 12-1 small block on 91 octane, but I don't run a lot of timing, and it required a lot richer jetting. I don't see why a 12 second car would need that much octane...mine is a mid 10 second car. I use real cold (10) NGK plugs.

 

[Lugnut79]

They're 492 cast iron heads. It pings horribly with 93 octane in it. The motor likes alot of timing. As of right now the plugs are gapped at .045 and its got pretty fat jets in it. I think 72 for primary's and 79 for secondaries. I guess I can try a cooler plug.


Edit:
Just thinking about it and it has developed a stumble when crusing around on the primaries and if I hit it to open the scondaries as has a slight hesitation before it kicks in. It never did this before. Maybe it is a jetting issue? The plugs being white and all.

 

[chevyIIheavy]

They're 492 cast iron heads. It pings horribly with 93 octane in it. The motor likes alot of timing. As of right now the plugs are gapped at .045 and its got pretty fat jets in it. I think 72 for primary's and 79 for secondaries. I guess I can try a cooler plug.


Edit:
Just thinking about it and it has developed a stumble when crusing around on the primaries and if I hit it to open the scondaries as has a slight hesitation before it kicks in. It never did this before. Maybe it is a jetting issue? The plugs being white and all.

um if your running 12 to 1 compression id say the fuel is the problem i would run straight race gas 110 or more. maybe take 2 degrees of timing out and see what happens obviously your motor doesnt like 38 degrees.

 

[Lugnut79]

um if your running 12 to 1 compression id say the fuel is the problem i would run straight race gas 110 or more. maybe take 2 degrees of timing out and see what happens obviously your motor doesnt like 38 degrees.

I'm running 50/50 93 octane and cam 2. I'm just trying to tell Bowtie0069 that it won't run on 93 I've tried in the past. I know he ran a 14:1 motor or something like that on pump gas back in the day but my motor doesn't like it.:no: Hence thats why Im mixing cam2 and 93 now. I ran 38* with the old ignition and never had a problem. Thats why I'm wondering if this new ignition requires a cooler plug. Nothing has changed in this picture except the ignition.

 

[levisnteeshirt]

maybe ,,,

maybe with the MSD it doesn't need as much advance ,, if i remember right , you've got some angle milled heads. Most of the time what i've saw , the smaller the chamber , the less advance you need. Or , how old is the gas you have ??

your cam is about 256 @.050 on a 112 isn't it ??

 

[Lugnut79]

maybe with the MSD it doesn't need as much advance ,, if i remember right , you've got some angle milled heads. Most of the time what i've saw , the smaller the chamber , the less advance you need. Or , how old is the gas you have ??

your cam is about 256 @.050 on a 112 isn't it ??

Yes sir you are correct. You know me better than my mother. The heads are milled .125 and are @ 58cc with .120 pop up pistons. The fuel is prob from around November 08. Its been sitting in my garage until a week ago since winter wont seem to quit around here. The cam is as follows.

Duration Advertised: 290° Intake / 298° Exhaust
Duration @ .050'' Lift: 252° Intake / 260° Exhaust
Valve Lift w/1.5 Rockers: .536'' Intake / .554'' Exhaust
Lobe Separation Angle: 112°

Would changing my springs so I'm all in at 3,000 instead of 2,500 help? How quickly does Race fuel go bad?

 

[64PRONOVA]

um if your running 12 to 1 compression id say the fuel is the problem i would run straight race gas 110 or more. maybe take 2 degrees of timing out and see what happens obviously your motor doesnt like 38 degrees.

With those heads, his engine probably would like to run at 38 degrees. Most do, but he might not have enough octane to do it. You can get around the problem by running over-rich and retarding the timing and that's alright but it's not optimal.

You always want to run the coldest plug you can get away with for more power but running rich and retarding the timing sacrifices HP. For a strip car, running cold plugs is the way to go since you aren't going very far and change them frequently but they won't last long on the street without fouling. You need a hotter plug for street driving to prevent fouling.

Everything is a compromise when running 1960s compression ratios with today's fuel.

I suspect that rather than there being a difference in energy from your new ignition causing the detonation, there is something else you are not seeing such as the exact ignition curve. The best thing to do at this point if you want to duplicate the old setup would be to re-install the old setup and then measure the exact ignition curve. The idle advance and the exact rate of advance throughout the RPM rage. Then try to set your new distributor up the same way by changing flyweight springs and limiting the mechanical advance if necessary. Having more spark energy isn't going to cause a dramatic detonation problem like you are seeing unless something else has changed.

 

[chevyIIheavy]

Yes sir you are correct. You know me better than my mother. The heads are milled .125 and are @ 58cc with .120 pop up pistons. The fuel is prob from around November 08. Its been sitting in my garage until a week ago since winter wont seem to quit around here. The cam is as follows.

Duration Advertised: 290° Intake / 298° Exhaust
Duration @ .050'' Lift: 252° Intake / 260° Exhaust
Valve Lift w/1.5 Rockers: .536'' Intake / .554'' Exhaust
Lobe Separation Angle: 112°

Would changing my springs so I'm all in at 3,000 instead of 2,500 help? How quickly does Race fuel go bad?

you baught a pro billit correct i think you may need to change the springs and lock it out . they come from msd on the conservitave side so your advance comes in slower. race fuel goes bad pretty quick but i dont know how long

 

[slickman]

I have just about the same MSD setup and I changed the springs to have all the advance in by 2800..