psears

Hello,

I just switched out my spark plugs in anticipation of balancing my
Weber carburators. I took out 6 NGK BP6E S plugs with around a 1000 miles on them (good shape) and replaced
them with 6 Beru Ultra-X plugs. Now the car runs worse then it did before! It defintely feels like it's either missing on a cylinder
now (I pushed on the spark plug wire boots as hard as I could) or
the plugs are gapped incorrectly (they're supposed to be pre-gapped at the factory), or they just suck, period.

Question 1: What do you all think of these kinds of plugs?

Question 2: What should the gap be on these plugs or on any other plugs being used? (I have a 3.0L SC w/GE-40 cams, 10:1 pistons, headwork & Webers)

Question 3: What is the best, most accurate type of gapping tool to use? I have the round coin type. (I've heard that you can't use the valve adjustment blade type-they don't measure correctly for some reason)

Thanks!

psears

Walt

No specific experience with this particular plug. I always use a flat feeler gage to check plug gaps, don't think the coin type is all that accurate.

Also, are you running the original wires? Pull off each wire and check continuity, maybe you have a break in one of the wires. If you took off more than one at a time, are you certain they are back in the correct location? Triple check to make sure the wires are snapped on good, I know this one from experience.

eugene

Make sure that it is of the same heat range as the NGK

ked

I am not convinced that the "modern hi-tech" plugs developed for super high voltage electronic ignition are optimized for carbed engines of the type like your SC.

Anyway, I have always found NGK plugs to be of high quality, reliable, long-lasting and, in particular, to be more tolerant of the wide range of mixture that carbed engines seem to display. They also seem to support a wide heat range. I might swap back to the NGKs to see if you get a positive change.

JPIII

I have been playing with engines for most of my adult life and I have never seen an engine as sensetive to spark plug changes as a carbed 911 engine.

Pure speculation on my part, but it may be because we are *forced* to run them rich on the idle circuit.

I agree with Mr Davis.
I have come to love NGK plugs.......cheep, too

jlkline

I think the gap would have to be really off to have the type of problem you describe. So Walt's thread oninspecting the wires,connectors, and location carefully might yield something. I've seen wires come apart right at the point where the wire enters the plug connector.

Also, it would be pretty odd, but could you have a bad plug that is causing the "miss"? If you can determine if the miss is specific to one cylinder, remove the plug, ground the threaded section and start the car to see if the electrode is firing.

psears

Thanks y'all for the inputs. I finally went back into my car and removed the Beru Ultra-X plugs & put back my newly cleaned & gapped (.031) NGK break-in plugs. While I was changing them back I pulled one of my wires out and noticed that the end of the boot connector had completely come of the main body of the connector! After some heavy praying & some luck I managed to get the part out of the spark plug hole & back onto the connector. Then, when I got to unscrewing the Beru plug out, it was shiny new & had obviously never fired once! However, the rest of the plugs that had been firing were sooty black for some reason (this after only about 2 days of driving on them.) Since I've put the NGK's back in, the car has been running fine (except for the warm-up popping & spitting problem, which, in anticipation of a carburator tuning, was the whole reason for the spark plug change to begin with)

FYI: I tried to find out what all the gaps for the 4 prongs on these Beru plugs were supposed to be, and know one knows-including the people who sold them to me. After some experimenting with my new wire gauge, I discovered that the two longer prongs opposing eachother were right around .031-.032; this is what Porsche recommended for R.O.W. cars for 1978-1983. The other, shorter prongs that oppose eachother are gapped ~.045-.050 or greater. I'll probably keep these on hand and try them again for my next plug change-making sure the wires get put on PERFECTLY next time!