I've got the same book as KurtV -- it's a great book. I also downloaded a copy of the factory service manual from Ernie Wilberg's excellent early 911 race car web site. . I believe that Ernie is a Pelicanhead.

I had the same problem with my 2.0S. Mostly fouling the plug when the car was idling for a long period of time.

I changed the ignition to a M&W CDI, I run the NGK BP8ES plugs with a 0.8mm gap. Haven't had a fouling problem since installing the new ignition.

I think the new unleaded fuel we get now days is just a soot magnet.

Would those NKG's - 7's or 8's also be good ones for my 67 (orig normal )with 2.2 E p/c's and a permatune.
My plugs are fouled ( Bosch WR8DP ) - everything else (wires, dist, compression, carbs ) check out ok.

Thanks;
John

If it help's, I'm running BP8ES's in my 67S motor with a bosch CDI ignition.. no problems whatsoever. I would think 135 main's are too much though, I run 125's with F3 emulsion tubes.

JCF,

The NGK 8/7s for summer/winter would be perfect for your '67 911 Normal!

One subject that hasn't been mentioned so far is plug gaps ... I don't recommend much variation outside the 0.028" - 0.032" range. Many others recommend huge plug gaps in the 0.045" - 0.060" range, but experience has shown [not just mine, but some mfrs] that wide gaps can cause misfiring because the high Voltage will find an easier path to follow, and that often means burned rotors arcing through to the distributor shaft, or down the coil output terminal insulator to a lower ground potential on the primary side, or down the distributor cap to dist. body ground, etc.

Some of you may recall that in the '70s when GM's HEI came out ... large gaps in the 0.045" range and above were recommended. GM and the plug mfrs have recently revised all specs for HEI systems back to 0.035" due to misfiring! It seems that hard-to-trace misfire problems with aging spark plug cables can be minimized by using an 0.035" spark plug gap. Nissan and Volkswagen have service bulletins makeing similar recommendations for certain engines prone to have misfire problems and widespread complaints from customers!

John (JCF),

Tell us more about your ’67 normal/2.2E. What heads? Did you physically measure the compression ratio?

The heat range of a sparkplug is sensitive to the temperature of the engine. Higher compression ratio = higher temperature. On track more full throttle = higher temperature.

Not knowing your compression ratio, I would install new BP8ES and inspect them after a week or two of normal driving. If the insulators are gray or lighter you have the right heat range. If black (or dark gray) then try a new set of BP7ES. On a lower compression engine and cold weather the BP6ES might be appropriate.

Best,
Grady

Our summers are usually not much different than our winters (though MUCH shorter) So maybe 7's ...
Though I will be doing a three day DE at Lime Rock in early Sept. so would the 8's be the better choice there ?

Grady;

The rebuild was done by a previous owner in 1982 - 27,000 miles ago.
The heads are the originals but were "fly cut" - what exactly does that mean ?
Cams are the original Solex.
P/C are Mahles.

Compression ; 151, 149, 151, 153, 151, 152
All plugs looked exactly the same (dark, not too oily)

R Replica seats (peter Z's)

Thanks guys.
It always amazes me how generous the folk here are with their time and help. Of course you could just be bored.

John

The Bosch Plat. WR8DP'sseemed to work fine till I drove the 200 miles back to Maine from the ALMS race at Lime Rock and then around town in that last heat wave. ( reached 100 even here)

John

I'm sorry to raise a very old question, but I can't find an answer to my query anywhere in the thread :-

I have recently acquired a 65 911, prepared to Appendix K ('67S spec), as a rally car.

The plugs in it when I bought it were B7ES, and they were set at around 0.030". When I consulted the manual, it said that they should be set at 0.015 or thereabouts.

When I cleaned and re-set them, it ran much better, but has fouling problems, not oil (as the motor is quite fresh), but fuel. Carbs (40IDS) are set up correctly.

After reading as many threads as I could on plug choice, I have bought a set of NGK BP7ES, but nowwhere in this thread can I see the recommended plug gap for a standard ignition (red coil, ballast resistor, points) car, with BP7ES plugs.

Not allowed to go CDi in Appendix K as far as I am aware, so does anyone have the info / experience of running a reasonably hot '67S motor on standard ignition, with these plugs ?
Would appreciate any info,
Steve
911ts3

Steve, if you are using 66-68 911S Heads and P&C's in your 65 Motor, you need a CDI....Plug gaps are not get going to resolve the fouling plug problem. All 66-68 911S carb'd cars needed a CDI box. The 911 normale motors did not. You motor is no longer "normal".... And that's a good thing ;)

Here's a look at your symptoms from another angle. Your ignition system has been fully covered.

Has your tech verified the carbs are setup/adjusted to spec? It would help to measure/confirm the CO and/or A/F ratio throughout the RPM range are within specs. A chassis dynomometer (rolling road) helps simulate road loads at speed as well.

A high float level can contribute to overly-rich mixtures and surely foul plugs. Don't mask plug-fouling symptoms by using hotter spark plugs. Engine damage at high speed can result.

Sherwood

Many thanks for your swift replies guys:-

Blau911
Like I said in my post, CDI's not allowed in Appendix K, so that's not an option. The car has run in appendix K from 1993 to 2007, with (presumably), B7ES NGK's, and I have seen footage of it going like stink.
Car had been stood for almost four years, and I have renewed leads, points, and rebuilt the carbs, (they'd only done around 2000 miles since their last rebuild and didn't really need a refresher kit ). Old petrol removed and using new stuff. Will renew coil and cap & rotor as a matter of course this week.

911pcars
Float height set correctly

I'd really like some advice on the gap I should be using for the BP7ES's in this engine.

Many thanks
Steve
911ts3

Not all high energy ign. boxes are CDI (capacitive-discharge ign.). E.g. Crane's Hi-6S is an induction-based ign. box. I have a used one for sale if interested. At a minimum, as suggested, invest in a pointless trigger to replace the breaker points.

Sherwood

Hi 911pcars,
you misunderstand, as far as I can make out (as the car is declared as running standard coil ignition on it's FIVA Competition Identity papers), for Appendix K, the car has to run with the standard '67S ignition system, so any sort of electronic ignition, or Pertronix / Aldon Ignitor type of aftermarket modification, is not allowed.
It has to run coil & points .

I guess I'll trial & error the gaps at 0.014" to 0.030" tomorrow (and a couple of settings in between), and see what it runs best at.

Keep coming with any suggestions for gaps though ! Might save me some time.

Steve
911ts3

With CDI, NGK7's and plug gap at .035 always worked for me on 2.0S and 2.0N engines. (Daily drivers in all weather for about 8 or 9 years.)

If you are still running points, make sure they are gapped correctly and clean not pitted. As the points wear, timing gets retarded, and you can really tell. Get one of those distributor magnetic inserts and can the points and condenser.

The Webers are very finicky. Will not tolerate any crud, and the old ones typically have the orifices full of sludge, especially in the fuel bowls.

The Weber carb book pictured above is not one of the better ones. John Passini wrote a great deal of Weber stuff and is very good. I have another book but forget the name/author. If you want me to find out, I'll go upstairs and look for it.

If no CDI, stick with Bosch Points and condenser and coil. Plug gap around .020-022. Points gap at .016 if I recall from 25 years ago.

If you want to wring max. efficiency out of the ign. system, you could have the ign. advance curve modified/maximized for your particular engine build.

- Ensure the cam lobe is concentric (fires the same relative to TDC on all six cylinders) (confirm on distributor machine)
- Confirm there's no point bounce at high rpm (confirm on distributor machine)
- Remove all slop from the distributor shaft.
- Lube and break in contact point rubbing block so gap (and static timing) change little.
- Use fresh copper or SS core spark plug wires, not radio-suppression.

Sherwood

Try NGK BP5ES. A little hotter. Seems better heat range for carbs.

A lot of good suggestions here. That's why this board is so great.

Fouling and Jets
 

IMO its jetted for flat out running at the autobahn.
A quick comparison with other cars of the period with Webers.
Alfa 1570cc/4cyl = 400cc per cyl
idle jet 50
main 115-120
venturi 30mm
power band 5-7k rpm

911 2000cc/6cyl = 333cc per cyl
idle 55
main 135
venturi ???
power band 5 -7k rpm

If it cleans up and idles well after a blast on the highway but the idle goes away after a bit of driving in traffic maybe just the next hotter plug is needed.

But without a wide band O2 sensor installed then the old fashioned way to check the mains is to run at over 3500rpm at least for a couple of miles quickly pull into a rest stop a pull a plug...black=rich, light tan=OK, white=lean.
The idle jets will tell you right away, a smooth livelier feel or a boggy feel by just driving around the block with the rpms less than 2500.

The jetting in the with 25% smaller cylinder displacement yet 21% larger idle jet does not make sense to me. Try giving Mike Pierce a call a Weber guru. 408-842-6667
No connection with Mike, just a source I have used for Weber parts and help.
Hope this helps!