Your plug gap depends more on what type of ignition system you have than what the plug material is. If you have a stock ignition system from the '60's, then your gap will be less. A modern system like MSD can put out a stronger spark, so you take advantage of that and open up the gap. With the specs you list I'd start at .035" for a stock ignition or .050" for a modern ignition. If you don't have any problems at the point, you can experiment & try to open up the gap a bit. MSD recommends with it's Digital 6 system the following settings:
Compression up to 10.5 spark plug gap of .050 to .060
From 10.5 to 13.0 spark plug gap of .040 to .050
Above 13.0 .035 to .040

Z. Ray

 

I was told NOT to use Platinum plugs with the MSD.

Is this statement true? False?

 

I was told NOT to use Platinum plugs with the MSD.

Is this statement true? False?

Were you given a reason why?

 

I am currently reading the MSD Tech Forums

MSD SPark Pugs Search results

And this one noted:

If you decide to upgrade to an MSD CD ignition such as the MSD 6300 which would give you added energy to the coil, then we recommend that you use a normal copper plug, staying away from any type of speciality or 'hype' plug. We would then recommend that you use a plug 1-2 steps colder than factory recommendations for the engine and you increase the gap on the plug in .005 increments until you get a nice clean burning plug. The plug should have a nice tan coloration on the porcelain when reading it. That gap will probably end up being .045-.060 .



MSD Tech repeats the use of 'copper plugs'.

I haven't found any specific call out of 'platinum' yet.

Search their tech info.

 

ah-ha!!!!

I found MSD's answer as to why NOT to use Platinum plugs.

SPARK PLUG
The MSD box will fire a $ .99 cent plug with the exact same intensity that it uses to fire a $6.00 plug. This is why we recommend you stay away from the so-called “hype plugs”. We are also aware that using the MSD with platinum plugs may increase the chances of pinging and detonating.

SPARK PLUG GAP
These examples are just starting points to get you going in the right direction. Every application is different and should be tested and tuned:
Compression Spark Plug Gap
Up to 10.5:1 .050 - .060
10.5:1 – 13.0:1 .040 - .050
Above 13.0:1 .035 - .045



There you have it! :thumbsup:

 

There are different types of platinum plugs. For example, Motorcraft Platinum spark plugs are similar to the non-platinum plugs, they still have a copper core. The platinum is the two small bits of metal you see at the tip of the electrodes. It's purpose is to prevent erosion of the electrodes- the platinum lasts 2-3 times as long as the regular steel electrodes and doesn't become rounded off.

Ford switched virtually all of their engines to platinum in the early to mid 1990s, and the platinum plugs replaced the non-platinum plugs for service replacements as well. I wouldn't call these plugs specialty or unusual.

However, I think what MSD is referring to is the plugs like the Splitfires, Bosch Platinum-4s, and the like that are advertised as "better" than regular plugs.

Jay

 

I use 2 dollar champion plugs, IMO platinums really do not give you much if any of an advantage, and the prices they cost its really not worth it unless they are necessary. And a previous post was right its really the ignition you have that determines gap. If you have an MSD or a box, check with them and the plug manufacturer. Champion recomends the gap at .035". Also I don't like to mount the coil on the block as the vibration from the engine will cause incomplete coil saturation which causes a weak spark (to give the short version).

 

I was all set to tout the use of Autolite APP-45 plugs with my MSD ignition system (MSD Digital 6 box, MSD ready-to-run distributor, & MSD 8.5 mm plug wires). But I thought, why not call MSD tech really quick before they close for the weekend to verify. Well, I stand corrected, the tech I spoke to nixed the use of the platinum plugs listed above, even though they are just platinum tipped on a copper core, not the all platinum variety. So I'm off to the parts store for some new all copper plugs.

An old dog can learn a new trick.

Z. Ray

 

Also back in the day every vintage Nascar small block and even vintage Boss 302 and 289 race motors that are very high compression run about .035-.040" so that is where I always like to stick with a stock style ignition. Like I said with an MSD it is possible to gap even further, but consult them for any specs they may have.