Spark Plug Gap:

[Orange69']

Hi all,

To ask please - on my 69' Charger, 383, I realize that the factory spark plug gap is 0.035. However, here are my upgrades to see if I should adjust that gap setting:

- EFI Fi-Tech,
- Electronic ignition,
- MSD red box,
- Mancini Racing distributor,
- Dual-field 90A alternator (1972 pig-style connection),
- Optima battery,
- Performer RPM intake,
- Taylor low-resistance wires,
- NGK5 plugs,
- In-tank electric fuel pump,
- MSD Vibration Coil,
- Driven 10w-40 synthetic blend racing oil (5 quarts).

Thank you for looking and sharing any input.

 

[RemCharger]

35 is as good as it gets. Plug will fire under all conditions.

 

[Geoff 2]

From MSD when it was MSD:
' Unblown engines 045" with stock dist cap & up to 060" with large dist cap'

 

[R413]

Compression ratio?

What does MSD red box mean? Does it have a number?

 

[69Bee]

I used MSD & an Accel coil then increased gap until it missed, then backed it off 0.005", ended up with a 0.055" plug gap with regular distributor cap.

 

[Bird 426]

This is like what's the best oil. FBO Ignition told me that you are just putting a strain on the system, anything over .035. Never have understood the wide range that everyone cars run at with plug gaps.

 

[WileE]

Hi all,
To ask please - on my 69' Charger, 383, I realize that the factory spark plug gap is 0.035. However, here are my upgrades to see if I should adjust that gap setting:

Nope.

 

[AR67GTX]

I experimented with wider gaps in my old BB Corvette when I had an Accell CD system in it. It seemed to always shorten plug life and start acting up so I returned to .035 in my old cars regardless of ignition. However, I have zip experience with MSD (May Suddenly Die) systems.

 

[R413]

I worked on a 318 with a 480 lift summit lumpity lump cam. It was running bad, plugs were gapped .020, opened up to .035 and it ran much better. Only change.

 

[not so famous bob]

Hi all,

To ask please - on my 69' Charger, 383, I realize that the factory spark plug gap is 0.035. However, here are my upgrades to see if I should adjust that gap setting:

- EFI Fi-Tech,
- Electronic ignition,
- MSD red box,
- Mancini Racing distributor,
- Dual-field 90A alternator (1972 pig-style connection),
- Optima battery,
- Performer RPM intake,
- Taylor low-resistance wires,
- NGK5 plugs,
- In-tank electric fuel pump,
- MSD Vibration Coil,
- Driven 10w-40 synthetic blend racing oil (5 quarts).

Thank you for looking and sharing any input.

I run .044 , msd 6 , MSD wires , dist. controlled f. inj., 505' wedge .

 

[Don Frelier]

A bit unrelated but on my 3.5 high output on my 300m it had 127,000 on the original plugs.
Ran fine now these are coil over plug and the gap was enormous as the plugs were literally worn out.
It probably had a gap of .070" or more.

 

[RemCharger]

Here's one I did recently on a 3.7 ford, somewhere around .090. It's all fun and games until you're burning your coils out

 

[Geoff 2]

Posts 11 & 12 are why GM reduced HEI 060 plug gaps down to 045. HEI was sooooo reliable that owners went beyond the tune up period, { car was running great } [ where plug gaps would be checked & reset if too large ] & the plug gaps became too large due to spark erosion......& took out the coils & modules. This was with the pathetic carbon string high tension leads with up to 30,000 ohms resistance.... With modern spiral wound wires, these failures may not have happened....
Use the biggest gap you can.....