Too much plug gap?
- Thread starter LaGrasta
- Start date
you'll lose performance and mileage...hear some pinging...etc.
Can you open yours up more? Possibly. You aren't running that aggressively. I had a similar set up running .055 gap and ran like a champ. I think I tried .065 and felt I had lost a little bit so I went back to .055 and was happy.
Can you open yours up more? Possibly. You aren't running that aggressively. I had a similar set up running .055 gap and ran like a champ. I think I tried .065 and felt I had lost a little bit so I went back to .055 and was happy.
66 Fastback
Famous Member
A bigger gap requires more voltage to jump the gap. Up to some limit, your ignition system will not be able to build enough voltage at the higher plug gap. It would probably manifest itself with misfires at the upper rpm range since the coil does not have enough time to build up enough voltage and energy between firings.
Doug
Doug
A cowboy answer:
I gap mine to 50-55 thou depending on mood. That's with a Bosch ignition module; close in output to the GM one people mount on a remote heatsink (punchier than the DS-II). It starts promptly, runs smoothly and doesn't misfire.
It erodes the plugs somewhat; you can tell when they need regapping, which is about every 8K miles or so as it runs a little rough and is harder to start. Regap, reinstall and you're away. If fouling is bad, I use a little spray of gun cleaner to remove carbon or oil deposits. A lot of plug changes (although plugs are considered cheap) are unnecessary expense IMO.
Regards, Adam.
I gap mine to 50-55 thou depending on mood. That's with a Bosch ignition module; close in output to the GM one people mount on a remote heatsink (punchier than the DS-II). It starts promptly, runs smoothly and doesn't misfire.
It erodes the plugs somewhat; you can tell when they need regapping, which is about every 8K miles or so as it runs a little rough and is harder to start. Regap, reinstall and you're away. If fouling is bad, I use a little spray of gun cleaner to remove carbon or oil deposits. A lot of plug changes (although plugs are considered cheap) are unnecessary expense IMO.
Regards, Adam.
james singleton
Well-known member
I will post a reverse question, while on the subject of spark plug gaps, what effect do you have "if" you stay with the stock gap (I believe .035") even if you have converted to a electronic ignition like the Duraspark or Petronix system??? The reason I ask, my plugs are gapped to .042" (with the Pertronix l system) and my plugs have a uniform black sooty look on all of them. It probably is a carb issue; maybe running a bit rich??? Jim
8) having run plug gaps as close as .020, and as wide as .060, i can tell you that gaps that run between .035 and .045 seem to be the best regardless of what ignition system you run. these gaps give the most consistent spark in my opinion. as for your plugs being sooty, you are getting too much fuel and a different plug gap wont make a difference.
66 Fastback
Famous Member
I have "cured" fouled plugs with an MSD ignition box. The higher voltage etc burns them clean. I know I am treating the sympton of too much fuel, but the car is an old dual 4 bbl set up, and I have problems finding jets etc to fit it. The MSD box also eliminated the points maintenance since they now carry minimal current and just trigger the MSD.
Doug
Doug
66 Fastback":1q68gaif said:
I put a msd box on my boat last year along with a new set of points and had to mess with them every time I took it out (every other week or so). I dont remember how long the last set of points were in there, guessing 5 years? never touched them. Could just be an issue from sitting weeks at a time, not sure if I am going to pull the box and use it somewhere else but I know I cant put up with it as bad as it was last season.
james singleton
Well-known member
Along with the Petronix Ignitor l ignition, I am running a 40,000 volt /1.5 ohm Ignitor Xtreme coil. I did not remove the "pink" resistence wire, so that is why I am using the 1.5 ohm coil instead of a 3.0ohm coil. According to the Petronix chart it looks like the lower ohm coils (1.5 or 0.6ohm) are used more for street racing than the higher ohm coils (3.0ohm); is this true?? I assume that there should be sufficient spark for my plugs with the 1.5ohm set-up?????? Jim
66 Fastback
Famous Member
TJH,
I have had the MSD box on my Corvette for 10 years and have not touched the points in that time. My points used to deteriorate in about 3000 miles prior to that.
I wired it with the white trigger wire as shown on the diagram of pg 10.
http://www.msdignition.com/pdf/6%20series/6series.pdf
Thinking back, I may not have been as successful on the Mustang. I would have to check my notes. But for some reason I was having problems with my Mustang after I installed the MSD. It may have been the points still deteriorating. I now have a Pertronix triggering the MSD box on the Mustang. Maybe some distributors are not as forgiving on the points in a triggering mode. But at that same time the Mustang was also suffering from a slipped harmonic balancer and a leaky Load-a-Matic vacuum can, so I don't recall the sequence of events.
Doug
I have had the MSD box on my Corvette for 10 years and have not touched the points in that time. My points used to deteriorate in about 3000 miles prior to that.
I wired it with the white trigger wire as shown on the diagram of pg 10.
http://www.msdignition.com/pdf/6%20series/6series.pdf
Thinking back, I may not have been as successful on the Mustang. I would have to check my notes. But for some reason I was having problems with my Mustang after I installed the MSD. It may have been the points still deteriorating. I now have a Pertronix triggering the MSD box on the Mustang. Maybe some distributors are not as forgiving on the points in a triggering mode. But at that same time the Mustang was also suffering from a slipped harmonic balancer and a leaky Load-a-Matic vacuum can, so I don't recall the sequence of events.
Doug
Am using .050 gap with DS2 setup.Starts easy,idles nicely,runs great.Leo
