Spark Plug Gap revisited...
 

Ok... there has been some discussion in the past on gaps==I have a '73 911T MFI, living in Denver; The porsche mechanic I purchased the car from said he had it set up a little rich--for the relative altitude and mountain driving. I just pulled the plugs out for a tune-up and found they have huge gaps: 0.8mm +!! Would it make sense that he allowed a bigger gap to help burn the slightly rich fuel mixture? I'm going to call him tomorrow--has anyone else experienced this? Anyone live nearby in the Rockies?

JW

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Let me know when you find out JW..
I just put some new plugs in mine and set them to factory specs (darn., can't remember the figure at the moment). That's a big gap tho! Maybe he just put the plugs in straight from the packet without gapping them.

I've recently discovered that MFI t's didn't run that well even when new. They were apparently rich runners even then. Quite how hard it is getting a T to run well now with different fuel and 28 year's wear is becomming clear to me now. Very tricky.

If I don't set my mixture on the rich side I get a hole at 2900-3200 which nothing I've tried (ie absolutely everything) can plug except more fuel.

Blame it on the designers. It never pays to detune a wild animal. They bite.

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'72 911 TE

Where can one find the stock gap? I'm about to replace the plugs in my '86 3.2 and I don't know what the gap is.

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Mark Szabo
1986 911 Targa 3.2

The spark plug gap was located in my '84 911's owner's manual.

Regards, Bruce

OK--I got some new info on gaps for my '73 911T w/MFI. The previous owner, a Porsche mechanic, said that factory MFI set-ups didn't really work the way they were supposed to from the factory. In fact, tweeking right off the showroom floor was common. Coupled with this, the factory spec gap didn't seem the best either. For here in Denver at least, he had the gaps set at .032". My MFI is set a little more rich than "factory" and the bigger gaps help burn this mixture better.

The huge gaps I found on the old plugs I pulled were from the mileage on them, he said. It was his experience that the gaps will grow/expand approx. .001" every 1000 mi., give or take.

So, .032 it is and the old '73T seems to like it like that in the Mile High City!

JW

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