MSD Ignition?

[Farmstore34]

Howdy all,
my '70 Chevy 4x4 that I bought came with all MSD ignition parts. There's the msd box on the inner fender, msd coil, cap, rotor, and spark plug wires. Do I need to gap the spark plugs differently than for a stock 350 ignition system?
Thanks!
Colby.

[RACINJASON22]

When ordering new parts this info will be suppied with the instruction along with parts. But to answer your question YES. MSD Ignition as well as most other after market systems can handle a greater plug gap for better combustion and performace. All the systems and depending on individual components change things though. I have seen some claim as high as .080 gap capibility but .060 is a good starting point IMO if you are purchasing used components with out instructions. just my .02

[jmking9]

I have all MSD parts (Distributer, 6AL, Blaster SS coil). At first I was unaware that you were supposed to gap them more. So I've tried it both ways, might be my imagination but it seems the truck runs much better with at least .060 gap. (IMO)

[GREASEMONKEY72]

gap all depends mostly on your application, but .060 sounds pretty good

[topnos]

You can look up the Installation instructions on MSD's website. But depending on the application and engine combination, the gap will vary. The only true method to ensure you have the correct gap is through testing and tuning. However, here is the reccomendation directly off of MSD's instructions for a 6 series ignition box.
Spark Plugs: Choosing the correct spark plug design and heat range is important when trying to get the best performance possible. Since there are so many engine combinations and manufacturers, MSD does not recommend which plug or gap is exactly right for your application.
It is recommended to follow the engine builder or manufacturer's specification for spark plugs. With that, you can then experiment with the plug gap to obtain the best performance.
The gap of the plugs can be opened in 0.005" increments, then tested until the best performance is obtained. MSD judges the plug gap by compression and components:
These examples are just staring 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: 0.050" - 0.060"
10.5:1 - 13.0:1: 0.040" - 0.050"
Above 13.0:1: 0.035" - 0.045"

[bryanw1968]

I have a complete MSD setup just as you do. I would NOT recommend running a huge gap. I tried a .060 as mentioned about and it ran but was a hooker monkey to start in the cold. I went back down to .040 and make the same power and have zero problems starting. Just because the MSD will allow a gap that big doesn't necessarily mean that you need one that big. You may be burning all the fuel at a smaller gap. You just have to play with it and see IMHO.

[RACINJASON22]

bryanw1968 states very good advise as well as others IMO. How you will run the truck and actual plugs all play a role in this equation.

[EAST SIDE LOW LIFE]

I'm using the MSD Box, Pertronix Blaster coil and the Pertronix ignition P/UP to replace the points in my distributor, this allows me to keep the old style distrbutor and plug wires. My gap is 35 thow and starts up like a charm, turns off and runs great.

Never thought of this before. Do you think I should make the plug gap wider?

esll.

[bryanw1968]

Well....The deal is, once you start widening gaps you need to consider the heat range in the plug you run, how you're going to drive it and what how much spark your distributor can throw. A colder plug likes to be rev'd higher all the time and is generally longer and a short plug(insulator) is hotter. I think that's the way it goes it's been a while sense I had to figure all this out for my setup.

Sound right RACINJASON22??

B-Dub

[GREASEMONKEY72]

Originally Posted by bryanw1968

hooker monkey

i like that, my trucks like that at times, now i have a new saying for it

[bryanw1968]

Originally Posted by GREASEMONKEY72

i like that, my trucks like that at times, now i have a new saying for it

I like it too! I can't claim it I stole it from a buddy of mine

[RACINJASON22]

Sound Very right to me bryanw1968. Maybe not so much on the lenght as manufaturers are differen but as far asheat ranges you've got the idea. There alot to consider when running Perfomance ignition system to actually get there full potential. Plug changes may very well be in order. multiple times infact. It can really come down to test and tune time to know the real differences.

EAST SIDE LOW LIFE: If it's running like a champ the only thing you can really do is as stated. Take a day and test/change it up a little one thing at a time so you have a base line to go back to. This is not nessasary unless you are really trying to max hp, mpg, ECT. ECT. You may gain some you may not.

I'm just a gearhead and like to max thing sout when possible but I will tell you I'm getting less into the test and tune thing, unless its on a race application. Some times the gains are minamal some times GR8.

[EAST SIDE LOW LIFE]

Originally Posted by RACINJASON22

Sound Very right to me bryanw1968. Maybe not so much on the lenght as manufaturers are differen but as far asheat ranges you've got the idea. There alot to consider when running Perfomance ignition system to actually get there full potential. Plug changes may very well be in order. multiple times infact. It can really come down to test and tune time to know the real differences.

EAST SIDE LOW LIFE: If it's running like a champ the only thing you can really do is as stated. Take a day and test/change it up a little one thing at a time so you have a base line to go back to. This is not nessasary unless you are really trying to max hp, mpg, ECT. ECT. You may gain some you may not.

I'm just a gearhead and like to max thing sout when possible but I will tell you I'm getting less into the test and tune thing, unless its on a race application. Some times the gains are minamal some times GR8.

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Your advice is good and I can relate to you on the tune thing. If something
works why mess with it that's my moto. I used to spend day's messing around with things but now I like it simple. I do not like stock unless it's a resto ride so I warm things over a bit, get a nice exhaust tune & cruise.

esll.

[Boog]

Originally Posted by EAST SIDE LOW LIFE

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so I warm things over a bit, get a nice exhaust tune & cruise.

esll.

Yeah, now we're talkin!

Actually I find the stock GM HEI is dead on reliable and if needed parts are available everywhere!