I recently replaced my stock coil and wires with MSD pieces. I understand that I can now increase my spark plug gapping to take full advantange of the greater current. So how much can I increase the gap? Will this benifit be worth the time it takes to change and re-gap all of the plugs?

Also, Is it worth going to a cooler plug? I may run nitrous in the future. If so should I go one or two stages cooler?

Any input would be appreciated.

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Black 1989 RS Convertible w/43,000 mi.
Excellent Condition
LO3 305 w/TBI
12 PSI Fuel Pressure
6* Timing Advance
MSD Coil And Wires
Open Element 14x3 K&N
Hypertech Thermomaster
160 Degree Thermostat
Low Temp Fan Switch
Eddlebrock RPM Muffler
No Cat/No AIR Injection
B&M Stage 2 Shift Kit
17"x8.5" ATP 5 Spoke Alloys
P 245/45 Goodyear Eagle
HP Ultra Plus Tires
Lakewood Control Arms
Lakewood Pan Hard Rod
Coming Soon:
Hedman Headers & Y Pipe
12 Bolt With 3.73 Gears
NOS System

 

you have to see what your car likes by testing it with an accelerometer.
I run the coldest plugs I can get and gap them to .033

using wide gaps lowers the current of the spark and can cause misfires or even detonation. It is usually harmless on a stock engine though.
the only benefits of wide gaps come at light throttle and idle in respect to fuel mileage & emissions.


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*I do custom performance mods on Edlebrock Performer carburetors (dualplane intake mods in the works),
White 1986 Irocz, 305 with iron #416 heads,
383 with aluminum TFS heads,
Edlebrock Performer-RPM intake and Performer #1407 carburetor, +110hp shot of crack, 700R-4 tranny, Vigilante 2400 lockup converter, 3.25:1 Ford 9" rear, Mcreary Road-Stars, SLP-stainless 1.75" shortie headers & Y-pipe, single 3" Borla exhaust, Linginfelter-TPI camshaft part number 74216 pulls 17" vacuum solid. Cam specs 213/219 @.050 114-LSA, sometimes advertised at 216/219 @.050 112-LSA .462/.470 lift @1.5:1 ratio. Using Harland Sharp 1.65:1 roller rockers. MSD-6AL, billet distributor, multi-retard, blaster-3 coil, and RPM switch. SouthSide machine subframe connectors, SSM lift-bars, Moroso 4" underdrive crank pulley.

N/A runs 10.9 @124,
Crack-runs 10.3 @135
haven't run at track since Oct-99
* vizit miy homepayge * http://www.geocities.com/trailerparkpage/

 

i did a lot of playing around with plug gap, timing, etc on my 91 Toyota truck. it was a great car to learn on. TRD was very helpful whenever I called.
here is what i learned.

increasing plug gap unshrouds the spark. I was running .48, stock was .32. it also delays the spark just a tiny bit, therefore retarding the timing. It takes just a tiny bit more time for the charge to build high enough on one elctrode to jump to the elctrode when the gap is wider

i gained more torque but lost top end power wit this mod.


Then i advanced my static timing by +4 degrees.

Coupled with the big gaps, this mod gave me a BIG SOTP difference in power. When I took my truck in for an oil change, they noticed the difference and couldn't believe it was just timing and plug gap.

I ended up with +3 degrees intial advance and .43 plug gap as my best compromise.

You see, i would lose power in the top end of the rpm range to gain power lower down.
mileage was fantastic. i went from 23.7 mpg average to 27.6 mpg average.

 

Thanks for the advice. It sounds like a nice gain in milage but I don't understand how the spark gap affected torque and horsepower the way you describe. Has anyone else played with their plug gap? How much is too much?
Is there anything else I should know before replacing them again?

------------------
Black 1989 RS Convertible w/43,000 mi.
Excellent Condition
LO3 305 w/TBI
12 PSI Fuel Pressure
6* Timing Advance
MSD Coil And Wires
Open Element 14x3 K&N
Hypertech Thermomaster
160 Degree Thermostat
Low Temp Fan Switch
Eddlebrock RPM Muffler
No Cat/No AIR Injection
B&M Stage 2 Shift Kit
17"x8.5" ATP 5 Spoke Alloys
P 245/45 Goodyear Eagle
HP Ultra Plus Tires
Lakewood Control Arms
Lakewood Pan Hard Rod
Coming Soon:
Hedman Headers & Y Pipe
12 Bolt With 3.73 Gears
NOS System