Spark Plug Gap Question
10-06-2010, 09:04 PM
#1
Launching!
Thread Starter
iTrader: (14)
Join Date: Jan 2010
Location: Wheaton, IL
Posts: 216
Likes: 0
Received 0 Likes
on
0 Posts
Spark Plug Gap Question I'm curious how the spark plug gap effects the performance of the engine. I see a lot of people with higher power cars running a bigger gap, but what are the advantages of this? The only thing I could think would be a longer spark would give more burn top the mixture? I've got an MSD ignition, 6a box, blaster coil, and super conductor wires so I would assume that a bigger gap wouldnt cause my setup to misfire or stumble. Any thoughts? Thanks, Also sorry if this is an obvious dumb question, just curious.
10-06-2010, 10:24 PM
#2
Other way around- closing the gap is the norm in response to increased power levels. In NA applications, rule of thumb is usually closing the gap .004 for each 50HP above stock. Say you've got mildly ported heads, moderate cam, full bolt ons and you're about 375 crank HP. You'd want to gap at about .042" rather than .050"
Also, if your CR goes above 11:1 you might be wise to go one heat range colder on the plugs (like going from the popular NGK TR55 to a TR6, heat range 5 > 6).
Nitrous and forced induction introduce a more complex approach. This usually includes a type of plug where the electrode is even recessed rather than the usual projected style (so the spark isn't 'blown out' before the air/fuel/NO2 mixture can be fully ignited).
Opening the gap above .050" on a stock engine is going to give you weak spark/no spark. Don't do it.
Also, if your CR goes above 11:1 you might be wise to go one heat range colder on the plugs (like going from the popular NGK TR55 to a TR6, heat range 5 > 6).
Nitrous and forced induction introduce a more complex approach. This usually includes a type of plug where the electrode is even recessed rather than the usual projected style (so the spark isn't 'blown out' before the air/fuel/NO2 mixture can be fully ignited).
Opening the gap above .050" on a stock engine is going to give you weak spark/no spark. Don't do it.
10-07-2010, 07:36 AM
#3
pretty much.......you want a good amount of gap while still retaining spark strength its a give take thing..........too much gap and the incomming air charge can blow out the spark not enough gap and your flame front from the plug wont be efficent for the burn......i've been playing with mine and the more i open it the better results I have which is usually the case untill it starts blowing out the spark........I've got a 13.9:1 CR NA 385 wit a MSD 7AL-2 Box, HVC Pro Coil and Moroso Super 40's 11mm and NGK BR7EF's.......I started down around .035 on the gap and worked it up right now I'm at .046 and the car runs fine and doesn't blow out the spark.....makes the best power there too.....
again every application is different but usually the more gap you can get away with while retaining a strong spark the better......
again every application is different but usually the more gap you can get away with while retaining a strong spark the better......
Trending Topics
10-07-2010, 02:34 PM
#8
oh yea you'll know about it lol......we had a turbo motor we built that kept doing it had to go down to .025 on the gap to stop it from blowing out the spark...........guess thats what happens when you jam 28psi into a 434sbc and max out the dyno before you get to peak power lol....
