Spark Plug gap to small? - Yellow Bullet Forums

Go Back   Yellow Bullet Forums > Technical Section > Turbo Charged - Blitzkrieg Motorsports

Turbo Charged - Blitzkrieg Motorsports

Reply
 
Thread Tools Display Modes
Old 04-03-2011, 04:27 PM   #1
Natas_69
Junior Member
Spooled up
 
Natas_69's Avatar
 
Join Date: Jun 2009
Posts: 179
Default Spark Plug gap to small?

What type of symptoms have you all seen when a spark gap is to small?

Vehicle in question was running @ .035" with out any issues. Then the motor wouldnt rev starting checking things out and regapped to .025". Nothing changed. Later realized it was the crank trigger pick up.

I never regapped the plugs; I am just curious as to what would be the results?
__________________
www.supernaturalturbo.com
Natas_69 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 04-03-2011, 06:47 PM   #2
Toaster64
Senior Member
Smoked another BBC
 
Toaster64's Avatar
 
Join Date: Dec 2008
Location: Los Angeles
Posts: 1,501
Default Re: Spark Plug gap to small?

A lot of people around here run .022 gap on booted apps. .035 is way to high, it will put the spark out...
__________________
Sponsors:
Deeds Perfomance
QMP Racing Engines
Fab-Tech
Mickey Thompson Tires
Mike's Transmissions
Precision Turbo & Engine
ARP
Ross Pistons

OUT 8.5 trim 4.960 @ 154 3340 lbs on Mickey Thompson slicks
4.802 @ 157 3360 lbs on 235's *MT's

No Mercy 4 Outlaw 8.5 Winner
NMCA West Outlaw 8.5 2013 Season Champion and Record holder
WCHRA Outlaw 8.5 2013 Season Champion and Record holder
SCSN 2012 Outlaw 8.5 Winner
Toaster64 is offline   Reply With Quote
Old 04-03-2011, 09:26 PM   #3
CW25
Junior Member
Pre-Staged
 
CW25's Avatar
 
Join Date: Apr 2010
Location: Grande Prairie Alberta
Posts: 81
Default Re: Spark Plug gap to small?

Us slower low boost guys run larger gaps. I run .032" no issues.
__________________
Curtis
1998 Dodge Dakota CC, installing 581 RWHP, 400BB, S475 remote mount, MSII and A/C blowing ice cold.
CW25 is offline   Reply With Quote
Old 04-03-2011, 09:29 PM   #4
stkjock
Senior Member
Smoked Another SBC
 
stkjock's Avatar
 
Join Date: May 2010
Posts: 9,115
Default Re: Spark Plug gap to small?

How much boost?

Small gap can cause the a/f mix to not burn well as I recall
__________________
Corn Powered Shelby GT500

L&M Built - 5.4L 4V - Lund Racing Tuned - 4.0L Whipple Charged
stkjock is offline   Reply With Quote
Old 04-04-2011, 11:11 AM   #5
Bellman
Senior Member
Smoked another BBC
 
Bellman's Avatar
 
Join Date: Mar 2007
Location: St. Louis Mo.
Posts: 2,974
Default Re: Spark Plug gap to small?

I set my gap at .018 with a Digital 7 with a 8261 HVC coil... With hot ignitions the gap will open up quicker than you think..
__________________
86 Mustang GT
383 ci Dart block
Precision PT88 turbo ( now armed with a Garrett GTX5518r )
Turbo 400 Tranny
http://www.youtube.com/watch?v=S-lAE..._order&list=UL
Bellman is offline   Reply With Quote
Old 04-04-2011, 12:11 PM   #6
boostedbowtie
Senior Member
Smoked Another SBC
 
boostedbowtie's Avatar
 
Join Date: Dec 2009
Location: Florida
Posts: 8,162
Default Re: Spark Plug gap to small?

Quote:
Originally Posted by Bellman View Post
Digital 7 with a 8261 HVC coil... will open up quicker than you think..

Yes it will . Mine is street driven with the 8251 and they open up fast .
boostedbowtie is offline   Reply With Quote
Old 04-04-2011, 12:22 PM   #7
MEAN_SBC
TURBOBULLET.COM BITCHES!
Smoked Another SBC
 
MEAN_SBC's Avatar
 
Join Date: Mar 2005
Location: Amarillo, Texas
Posts: 6,298
Default Re: Spark Plug gap to small?

Quote:
Originally Posted by Bellman View Post
I set my gap at .018 with a Digital 7 with a 8261 HVC coil... With hot ignitions the gap will open up quicker than you think..
X2.. This is what I run.
__________________
Brant Campbell
Worlds Fastest MPH Car on 275's
6.92@212.09
2011 PSCA XDR/TT5 Champion
2011 PSCA Sin City Shootout Champion

Thanks To The Following:
MEAN_SBC is offline   Reply With Quote
Old 04-04-2011, 01:29 PM   #8
NCR Motorsports
Senior Member
Smoked another BBC
 
NCR Motorsports's Avatar
 
Join Date: Aug 2007
Location: Illinois
Posts: 1,392
Default Re: Spark Plug gap to small?

What we run on the T/S car also...
__________________
Top Sportsman
BS3 EFI-F3 Procharger on Alky
www.benboardracing.com
Midwest Chassis and Performance www.midwestchassis.com
Bob @ Kurgan Motorsports
www.kurganmotorsports.com
Lenny @ Ultimate Converter Concepts

www.NCRMotorsports.com
NCR Motorsports is offline   Reply With Quote
Old 04-04-2011, 04:40 PM   #9
BruceWilkie
Junior Member
Launchin
 
Join Date: Apr 2009
Location: Murfreesboro TN
Posts: 426
Default Re: Spark Plug gap to small?

Quote:
Originally Posted by stkjock View Post
How much boost?

Small gap can cause the a/f mix to not burn well as I recall
Small gap with spark is better than large gap with no spark! Type of ignition(capacitive or inductive) you run matters too!
BruceWilkie is offline   Reply With Quote
Old 04-04-2011, 04:54 PM   #10
stkjock
Senior Member
Smoked Another SBC
 
stkjock's Avatar
 
Join Date: May 2010
Posts: 9,115
Default Re: Spark Plug gap to small?

Quote:
Originally Posted by BruceWilkie View Post
Small gap with spark is better than large gap with no spark! Type of ignition(capacitive or inductive) you run matters too!
agreed. however the OP question was what happens when it's too small.
__________________
Corn Powered Shelby GT500

L&M Built - 5.4L 4V - Lund Racing Tuned - 4.0L Whipple Charged
stkjock is offline   Reply With Quote
Old 04-04-2011, 05:13 PM   #11
BruceWilkie
Junior Member
Launchin
 
Join Date: Apr 2009
Location: Murfreesboro TN
Posts: 426
Default Re: Spark Plug gap to small?

Hope this answers the question
http://www.ngk.com/charglossary.asp?kw=Gap+Settings

Gap Settings

A spark plugs’ tip temperature and the voltage necessary to fire the plug are directly affected by the gap setting. NGK sets the gap from the factory for that plugs most popular application. Unfortunately, that plug may have hundreds of applications from automobiles to golf carts. Setting the gap for your particular engine is important as insufficient spark plug gap can cause pre-ignition, detonation and even engine damage. Whereas too much gap can result in a higher rate of misfires, loss of power, plug fouling and poor fuel economy. Even if the preset gap is supposed to match your motor, it is always best to physically check that the gap is adjusted properly for your motor prior to installation.
For modified motors, proper gapping is essential; gap settings are affected by increased compression, fuel type, turbos, nitrous and high output ignition system. Most experienced tuners know that opening the gap up to present a larger spark to the air/fuel mixture maximizes burn efficiency, however, after they have raised compression and installed a turbo, they have to lower the gap (to ensure ignitability in the denser air/fuel mixtures). It is for this reason that most racers add high power ignition systems. The added power allows them to reopen the gap without misfire.

You may also want to read through here. http://www.ngk.com/search_char.asp?s...nufacturerID=1
BruceWilkie is offline   Reply With Quote
Old 04-04-2011, 05:45 PM   #12
promodefi
Member
Pullin gears
 
Join Date: Oct 2007
Location: East of the Rockies
Posts: 680
Default Re: Spark Plug gap to small?

.018-.020 is the typical range for everything we run including a 44 mag. The smaller MSD's can definately use .018 with no problems. You can usually tell if you are too tight if the idle is eratic. But max power under hi boost is usually between .018 and .020.

I was tuning a bonneville car for a customer with a naturally aspirated mechanical injected alcohol engine with 20% nitro running a Don Zig massaged mallory mag and the customer was insistent on running .035 gap. The car would shoot ducks all the way down the course and you couldn't pull enough fuel away from it to get heat in the plug and smooth it out. I finally talked them into .025 we had to add fuel and finally set the record. Had the car in impound and they opened the plug gap back up to .030. Made the run the next morning and failed miserably. Again the car shot ducks all the way down the course. They finally called Don Zig and the word was if you run anything over .020 you are crazy......that wasn't the exact words he used they were a little more harsh.

You wouldn't think .005 would make a difference but it is huge from even .025 down to .020 and from .025 to .030 was a deal breaker......cost them the record!!!

If the car is a 12 second car you probably aren't going to notice a difference. If it is a 10 second car or faster with some substantial cyl. pressure you will probably pick up some numbers if you go down to .018-.020.
promodefi is offline   Reply With Quote
Old 04-04-2011, 05:54 PM   #13
Mark55
Member
Pullin gears
 
Mark55's Avatar
 
Join Date: Sep 2008
Location: Rockford, Mi.
Posts: 579
Default Re: Spark Plug gap to small?

Any closing the plug gap down to get it to fire at high boost / high rpm is a band aid for a single coil system.

There's no escaping the physics of it. There is just not enough coil charge time to fire 4 cylnders per revolution at high rpm.
__________________

21' Eliminator Daytona V-Drive
540 Arias, BW 75mm turbo's,
FAST XFI/XIM, E85 Fuel, 1800 HP lake boat.
Mark55 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -4. The time now is 06:19 AM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.
Resources saved on this page: MySQL 3.45%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Yellow Bullet LLC