What is the recommended spark plug gap?

[knuckle_buster]

I am installing an Edis/mvlt on revmaster VW based engine, What kind of spark plug and what is the recommended gap for the plug. The engine was set up with a magneto, so it has aircraft type plugs in it now. I modified the original wires to addapt to the Ford coil packs. I've had the engine running this way, but only for a moment on ether.

[knuckle_buster]

I guess I didn't make myself too clear. Maybe I should ask what plugs are some of you using and in what motor? Then maybe some one can get brave enough to mention what spark plug gap they are using!!

[capri_turbo]

stage 3 2.1 Pinto (2.25mm overbore on a Sierra 205 block), Piper 285 Cam, serious headwork, 38DGAS carb.

I'm currently running with NGK AP7FS (standards for the pinto engine in the Capri are AP6FS) with a gap of 1mm... (standard gap for Capri is 0.64mm).

[KLAS]

i am running Accel 113 plugs with 1mm gap in my Mini
factory ignition asked for 0,8mm

[MartinM]

When I had my engine rolling road tuned, we opened the gaps from 1mm (25thou) to 1.6mm (40 thou)

Some of the considerations were:
- EDIS wasted spark coils produce much bigger secondary voltages than a 'traditional' (aka old fashioned) single coil that is producing twice as many sparks per unit time
- a physically bigger spark is better

Seemed to work very well, but we didn't do a controlled test of max power at 25 thou vs. 40 thou at the the same rpm/load point ...

Martin

[DannyP]

Haven't been on line in a while, but I am running NGK DP8EA9 set at .040 in my type1. It is however currently sparked with a Mallory Hyfire6, triggered by a Perlux ignitor in an 009. Megajolt to be installed soon! I need to pull the motor to install the trigger wheel.

Oh yeah, am running a 2165cc type 1, 10.1/1 compression, 1.5/1 Pauter roller rockers, 040 heads(huge valves, flow benched,port-matched), and Webcam 86B. Induction is dual Weber 44 IDF, exhaust is 1 and 5/8 primarys, 4 into two Magnaflows, into one 3" exit

[xflow7]

When I had my engine rolling road tuned, we opened the gaps from 1mm (25thou) to 1.6mm (40 thou)

Some of the considerations were:
- EDIS wasted spark coils produce much bigger secondary voltages than a 'traditional' (aka old fashioned) single coil that is producing twice as many sparks per unit time
- a physically bigger spark is better

Seemed to work very well, but we didn't do a controlled test of max power at 25 thou vs. 40 thou at the the same rpm/load point ...

Martin

Just to prevent some confusion, you have a units conversion error up there. 1mm = 0.0393".

Dave

[MartinM]

Sure do! Well spotted

I still work in imperial when it comes to plug gaps but tried to be clever and make it look like I'm a metric man, so the imperial ones are the one to go for and it should be:
- was 25 thou (0.6mm)
- now 40 thou (1mm)

...give or take a decimal place or two...