Charlie,

          Humour is when I say it, sarcasm is when somebody else thinks of it first!.

 Ted, I am running an MSD blaster, but the blower makes my experiences in this car not directly transferable. I have not had any top end misfire issues, that I'm aware of, with the Duraspark, Flamethrower, 6AL combo. But, if I can quit breaking parts long enough to get a couple of runs in, I will try closing the gaps up to see if there's any noticeable difference.

Frank/Rebop

Bristol, In ( by Elkhart) 

I'm still reading and learning about this - ...the inductive systems we are running get a certain amount of electrical energy into the coil primary - volts/amps/and charge time (dwell). Then the circuit is broken and the secondary "fires" - makes the inductive energy jump through the wiring to the plug and across the gap.

The energy is volts times amps - and whatever it takes in volts to make the jump, reduces the amps (and vice versa). It supposedly takes about 10,000 volts to fire a pressurized engine cylinder - don't know what gap is assumed there - but if the gap is enlarged and the volts raise - the amps must fall.

When we are welding - we adjust amps to get the heat right - my guess is, that when we fool with the plug gaps, we are adjusting the balance between amps and volts to suit the compression/mixture - and get the heat right.

 
 Steve Metzger       Tucson, Arizona

My sense of humor is left of left field but not in the grand stands. I actually have difficulty recognizing humor and sarcasm. I understand the concept but I generally don't get it in practice. Anyway, this doesn't relate to ignition.


Lawrenceville, GA

Ted, it looks as if you have this subject down. Although I run a .045 gap in my "Y" with a strong coil and 9.0:1 comp. I recently installed a supercharger on my Triumph and found that under hard acceleration ( and 7lbs boost) it would "crap out", but with simpley closing the gap from .035 to .025 it took care of the problem. I do plan on installing an MSD system on this car but it's more for the "Boost retard".

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Charlie.  This proves you do have a sense of humor.  For you, I’ll change ‘pointless’ to ‘breakerless’.

 

Frank.  Thanks for the kind words but spark plug life in the roadster's Y is like my other race cars in that the plugs want to last forever.  You gotta thank modern ‘breakerless’ ignitions for that.  Looking back through the records for that particular engine, the plugs were changed out at the Birdsapallooza event in May of 2005 and have been doing their job since without a hiccup.  But you’re right on the jetting as I’m always adjusting on that.  Regarding spark plug gaps, I believe Steve Metzger pretty well covered it in a post he wrote yesterday in a separate but similar thread.

http://www.y-blocksforever.com/forums/Topic17921-3-2.aspx

 

But this is a good topic as it gets the mental juices to flowing so I’ll add some more thoughts.  Leaner mixtures typically like a wider gap and fuel injection systems in general puts an emphasis on ‘lean’ during cruise situations.  In a lean situation, a wider gap give the spark more time to ‘find’ and ignite the mixture.  On a sidenote, the BG Demon line of carburetors will typically like both a wider plug gap and increased advance for the initial ignition timing settings more so than the Holley carbs simply because of the leaner idle and cruise mixtures they exhibit.  I do recognize that the requirements between idle/cruise and full throttle are also different in regards to spark plug gapping.

 

On the flip side, higher combustion pressures increases the need for a stronger spark while maintaining a given gap.  Because the ignition system is either maxed out already or not being upgraded, the spark plug gap is easily reduced to fit any increases in demands that are being placed upon the ignition system.  I simply run across too many instances in a performance situation where an engine is misfiring at the top end of its power band and the first thing I do is have the customer reduce the plug gap which in a majority of the cases is the fix.  I get chastized quite a bit for sending engines out of the shop with a smaller than recommended plug gap but it’s one area of troubleshooting that does not have to be revisited if an issue crops up.

 

I recently reduced the gap in my roadster engine from 0.035” (Columbus setting) to 0.025” and was rewarded with a personal best for the Y engine that resides between the rails.  These are the same plugs that I’ve been running since 2005 but simply regapped.  I’ll accept that the et reduction wasn’t all plug gap related as the air was good but still feel confident that plug gapping was still a contributor.  This is something I picked up from recent dyno testing where spark plug gapping was the emphasis and simply put those learnings to use on the car.  Again, this is full throttle testing which will differ from cruise situations.

 

Here’s an et slip from a couple of weeks ago with the 0.025” plug gaps.  As an FYI, the slowest pass for the day was a 9.67 et.  I’m car # 411E and in the right lane.

 

Lorena, Texas (South of Waco)

Frank/Rebop

Bristol, In ( by Elkhart) 

Frank, I am like you .I am not picky about a lot of thngs I just want it to run good. My engine was just rebuilt so I hope it has no leaks (yet).But ,being new to MSD I needed to know what was the way to go with it. I do think a wider gap would work better ,but I ain't no electrical engineer so I dont know .So, I will keep the gap as is for now and see what happens in a couple hundred miles and pull one and see what it loks like and make a decision. Maybe by then I will have some leaks and I will know what to do . Thanks for all the help

55Birdman  Hickory NC

Earl,

        See, this modern electronic stuff is amazing ain't it!

       More on Ted's comments, spent some time thinking about what he said today. Some of this is guesswork on my part, based on knowing how thorough Ted is and how "picky" for lack of a better word, he is. I would guess that his plugs are usually new, his jetting is on and the motors he runs are usually sealed up and not burning oil. Based on that, he might not see much if any difference with a .045 gap versus a .035. I would expect the major improvement to be in less optimum cases where there's some oil burning and a less than perfect mixture. I did notice some improvement in the blown car, with old wires, by closing my gaps to 42 from 45. On my Pontiacs, the MPH would pick up by going wider. No blower, 9 to 1 compression and a Quadrajet Carb. My Windsor doesn't seem to care, but it idles better with the bigger gaps. 

   

Frank/Rebop

Bristol, In ( by Elkhart) 

The MSD is installed. I put in new plugs when I installed my 113 heads . I didnt want to pull them to regap them because they are a pain to get out around the Powertrain headers. I decided not to . So after everything was inplace and checked I fired it up and all I can say is "WOW".

55Birdman  Hickory NC

If I spend all that money on an ignition it better not be pointless.






















Lawrenceville, GA