Spark plugs

[Nivels]

I have a 468 chevy in a 20 foot Spectra V- Drive
The motor runs on a Vertex Mag 36% total advance. For years I have been using Autolite #13 or #22 plugs and have since changed to Autolite platinum ap#23. What do you guys use.

[Timer]

Nivels, I've got a 468 v-drive that used to have a magneto in it. Just went to MSD but I didn't change the plugs. Next time I can I'll check a plug and see what the previous owner was running.

[superdave013]

Timer, You might want to check your plug gap. A mag likes the gap around .018 -.020". With your MSD you can run much more gap. Hey, you should be keeping an eye on your plugs anyway.
[This message has been edited by superdave013 (edited June 13, 2001).]

[SPECTRABRENT]

Nivels,
Please visit the Spectra web site. www.spectramarine.com. (http://www.spectramarine.com.)
SpectraBrent

[Timer]

Hmmmm, good point superdave013. Both setups are new to me and I've been away from high perf engines for years, so thanks for the reminder. (We'll see if my man made that gap change.)

[Dimarco Kid]

Blown 490 Chevy and running 44TS AC Delco's. Love em' always will run em'. Also, Daves right about your gap. Keep it tighter.

[Timer]

Nivels & superdave013,
I just pulled a plug. It's an NGK R UR4 V-POWER with a gap of .036" to .037". Looks like an extended tip type. I'm guessing this was the gap used with the magneto. Am I right superdave013?
The plug was black. I guess that could be explained either by the launch ramp idling or 2 holleys on a tunnel ram, or both. I know I should be checking them after a WOT run.

[ponponracing]

From my experience run a magneto with steel spark plugs wires, gap should be .025. If you swich to electronic, you have to use silicone (non-solid) wires. Gap should be at a minimum .035 to whatever you like them. From many dyno. tests, .035 always gave me the best hp numbers. If you run solid wires with MSD, you're goofing.

[Timer]

ponpon, I'm pretty sure the wires came with the MSD, so they should be right. It sounds like you think the gap is right, also. I seem to remember that a gap of around .060" has been recommended in some literature for high energy ignition systems. Am I going senile (it's happened before)?

[superdave013]

Timer, Nope, that gap is was to much for a mag. Your man must have re-gapped them.

[Timer]

Regarding the plug gap with the MSD ignition, following is the question I sent to the MSD techs and their reply:
Question:
I have a 468 Chevy in my v-drive boat and your MSD 6M-2 ignition system. The plugs are NGK R UR4 V-POWER set at about .036" gap. Are the plugs and gap OK? If not, what would you suggest?
Answer:
We do not have a preference to spark plug brand, brand of choice. We do offer a starting point to get you started
COMPRESSION SPARK PLUG GAP
up to 10.5:1 0.050"-0.060"
10.5:1-13.0:1 0.040"-0.050"
above 13.0:1 0.035"-0.045"
Open gap in 0.005" increments until best performance is obtained. The only thing we do recommend is to stay away from "hype plugs".
Thanks
MSD Tech

[Nivels]

Superdave
Your right on the gap of 18 to 20. My question had to do with the heat range of the plug. Timer why did you switch to MSD?

[superdave013]

I run blown & turbo charged engines. So I run colder plugs. I use autolight #133. To cold for what your doing. I would run the #13's in your deal. I'm sure the others will be ok, just never used them. Oh, I don't really buy into the platinum or fancy tip deals. I change them too often.
Vertex mags are great. The ones with the external coils are even better.
I ran a Mallory supermag 3. When I switched to MSD my boat starts better. I have better control of the timming. (Mallory mags suck for that) I have a soft touch rev control that works great. Oh, no point to deal with.
In your cruiser you will like an MSD set up.

[Timer]

Nivels, I changed the magneto for the MSD because I was told the magneto has magnets that are expensive to have aligned (?) and it doesn't have the energy/burning efficiency of the MSD at different RPMs. I had no experience with either type of system.
[This message has been edited by Timer (edited June 20, 2001).]

[ULTRA28]

sorry, wrong post
[This message has been edited by ULTRA28 (edited July 06, 2001).]