Another spark plug thread …, WR5DC+ plugs in an RS Spec 2.7l 914/6 Options

[Rufus]

I’m having trouble keeping the Bosch WR5DC+ (7992) plugs in my 914/6 from fouling.

The engine is an RS spec 2.7l except with Webers & more aggressive cams w/ faster acceleration ramps.

I’m thinking the operating conditions are causing the problem; frequent moderate to heavy traffic, numerous traffic lights, and 45 mph speed limits half the time.

Despite the CDI ignition, keeping revs @ 2000 at traffic lights, and rpm above 3000 while moving, the plugs foul quickly.

Planning to change to the next step hotter plug … WR6DC+ (7995) and see what happens.

Comments? Anyone have experience w/ a similar engine configuration?

Feeling like even driving on open roads w/ 60 mph speed limits the “5” would be too cold.

[slivel]

I ran these when it was track only:
Spark Plugs: NGK BPR7ES (5534 large 13/16 base), or BKR7E (4644 small 5/8 base)
But now that the car is occasional drive to car shows or some canyon carving I thought that I'd have to change plugs to a hotter heat range but it seems to be doing well and no fouling with the same plugs that I used for years when racing. It is crankfired twin-plug so maybe that helps keep the plugs clean. I recommend the small base plugs because it makes servicing the lower ones much easier.

Also maybe your idle jets are too large. This is my track configuration:
Induction: Weber IDE46, chokes: 40, main jets: 185, idle jets: 60, air correctors: 155, emulsion tubes: F7
But with mufflers installed and no more open exhaust, I reduced the mains to 160's. I'm probably down 30 horsepower with this.