ignition help '67 911S

rearwheel · 10-09-2004, 12:23 PM

I have a 1967 911S engine with the Bosch distributor and Weber carbs with ignition problems.

I get no noticeable change in engine idle when I pull any (or all) of the right side plug wires. Pulling any of the left side wires kills the car at idle.

I recently did a carb overhaul and noticed similar problems in adjusting the idle mixture. Basically, there was no affect on engine performance for any mixture setting for the right side.

All the plug wires are new today. I pulled one of the plugs from the right side to take a look at it and it looks blackened (carbon deposits).

Any help on where to look next is appreciated.

Early_S_Man · 10-09-2004, 02:34 PM

Pull all of your spark plugs and post pics if you have a digital camera. Be prepared to replace your spark plugs before expecting to proceed with other tuneup issues and areas. Your ignition system must be in perfect shape before attempting to adjust carbs!

I strongly suggest that you plan to retrofit a Bosch CDI system to your engine ... that is what the factory did to 1969 models ... specifically to cure spark plug fouling problems!

rearwheel · 10-09-2004, 04:20 PM

I'll post pictures tomorrow. It's interesting you mention the 1969 CDI system. I already have it, but it is not in play. The body is a 1969 911T but at some time in its past the engine was swapped for the 1967 911S. As far as I can tell, they left the CDI box (diconnected). I'll post a picture of that as well.

rearwheel · 10-10-2004, 06:54 AM

Here a picture of the plugs. I didn't come out as well as I had hoped. In comparing the left side to the right side, the left ones are not as black (slight red coloration), but overall the plugs look most like the ones with carbon deposits.

I have not changed the plugs since I've had the car and have less than 8 miles on them since the carb overhaul.

Also included is a photo of the ignition components leftover from the 69 to 67 engine conversion. Am I correct that the box in the front (nearest driver) is the CDI box? What is the other box with Bosch visible on it?

RoninLB · 10-10-2004, 07:27 AM

5 DP plug numbers ?

how about a pic of the plug tips facing the camera ?

rearwheel · 10-10-2004, 07:53 AM

Ok, here's a better picture of the plugs standing up.

All the plugs are Bosch Platin : WR 5 DP

After the word GERMANY, the right ones are: R6 465 and the left front and back are R6 371 (the middle is also R6 465). Not sure what difference 371 vs. 465, but I'm having troubles on the right side...

Fidalgo911S · 10-10-2004, 01:37 PM

In my opinion, first thing you should do is get rid of the Bosch Platinums. They foul up so fast on my '67 S, it makes driving fun for only the first couple of miles. I use NGK BP7ES on all cylinders except #1 where I use a BP6ES.

I use a hotter plug on #1 cylinder because it runs so cool. I'm able to go all year on one set. Plus the cost savings are huge. There may be many that disagree about NGK vs. Bosch, but that's my two cents.

Nate

buster73 · buster73's Garage

Would be surprised if this is an ignition problem, as there is no good reason that only one cylinder bank is not working properly (as long as cables and spark plugs are ok). Make sure you carbs are working properly and your mixture is not off on one side. Could be just the idle circuit.