[alfaed]

Hope someone can help with this problem on my 68 roundtail, i have an issue with my plugs fouling with black carbon deposits which would suggest a rich mixture.

I have recently changed the dizzy cap, rotor arm, points & condensor, golden lodge plugs changed to NGK's about 6 months ago, a new refurbed fispa filter regulator installed.

The fouling seems worse now than ever, the car runs fine however and starts everytme with no issues.

I've also adjusted the carbs, twin 40's and according to the factory manual, the mixture screws should be a half a turn out on the idle settings, this seems contrary to everything i've read here were they should be 1 to 2 turns out.

Could it be timing, float levels, distributor problems, fuel problems.

Any help would be most welcome.

 

[papajam]

I've also adjusted the carbs, twin 40's and according to the factory manual, the mixture screws should be a half a turn out on the idle settings, this seems contrary to everything i've read here were they should be 1 to 2 turns out.

If you have a 1750 with the stock jetted Weber 40 DCOE 32, I've found that the proper mixture is achieved anywhere between 1/2 and one full turn out. It's the later model emission carbs that require more turns on the mixture screws.
Two questions;
1) what NGK plugs are you running
2) what is the engines oil consumption

 

[alfaed]

Hi Papajam, Thanks for the quick reply,

in answer to your questions It's actually the 1300 junior standard euro spec model, i'm running BP7ES plugs, some amount of oil consumption but not big,

it's definitely carbon fouling, not oil, the plug tip is dry

 

[ddouglas77]

I've also adjusted the carbs, twin 40's and according to the factory manual, the mixture screws should be a half a turn out on the idle settings, this seems contrary to everything i've read here were they should be 1 to 2 turns out.

The factory manual doesn't tell you to use a vacuum guage to set it? I do it by ear on American cars, but even on the those, manuals say to use a vacuum guage to set the idle mixture screws...

 

[Cosmo]

You use a vacuum guage to set the balance right between the throttle spindles on the two carbs.

To set the idle mixture, the best thing to use is a Colortune.