NGK plug chart

[darrel]

While I was going through my '79 620 factory manual, I noticed it called for a couple of different plugs, each gapped differently. The '79 is completely stock and unmolested.

 

'79 620 factory service manual page # EE33

 

BPR6ES @ .031 to .035

 

BPR6ES-11 @ .039 to .043

 

 

I replaced the plugs with BPR6ES and gapped them at .039 to .043.

 

The plugs I took out was a combination of both.

 

What is the good and bad with running a larger/smaller gap than what the manual calls for each plug?

 

It seems the only difference is the gap. Both are resistor plugs.

 

 

Here's the chart.

 

Maybe someone could put this chart in the FAQ section if it isn't there already.

 

[Laecaon]

The 2 plugs are identical, minus gap. The 11 comes pregapped. That is all.

 

Only other thing I would wonder about is running a BP6ES, that is, not being a resistor plug. Seems like many do it, as when they swap the dizzy to a 510 they fail to look up what the dizzy wants. I wonder what the difference would do in this motor.

[ggzilla]

The -11 comes pre-gapped for electronic ignition (large gap)

 

What is the good and bad with running a larger/smaller gap than what the manual calls for each plug?

Don't do it, as your performance will drop off. You might not notice it, but you can tell by timing 1/4 mile or by tracking fuel economy.

The low side of the spec is generally more power, the high side is generally more smooth.

 

The dizzy doesn't 'want' any specific spark plug. The engine needs a certain type and heat range, and the coil wants a certain type. Stock coil wants a 0.35 gap. Datsun EI coil wants a 0.42 gap.