354 spark plug fouling

[WNM]

I"ll get this right yet!!

Recently purchased 354 which fouls plugs very quickly The carb is the British Zenith VN which I was told recently rebuilt I replaced the air filter and there is no problem with the choke working correctly I understand there are shims below the fuel inlet which adjust the fuel level? I have never worked on a carb like this so any information will be appreciated

Thanks

 

[Roger in Iowa]

Are the plugs fouling from fuel or oil? Is the engine smoking? Blue smoke or black? Blue is from oil. Black is fuel.

 

[WNM]

(reply to post at 15:16:26 10/17/20)

Definitely fuel They are a sooty black within a few hours of use First thing I though of was a rich mixture but an adjust made no difference Thats why I thought maybe float level is too high

 

[old]

What brand of spark plug does it have in it?? Also it could be a plug tht is to cool. Me I use NGK plugs in every thing since now days Champs and auto lite plugs are junk and made in the land of almost right

 

[WNM]

[q

uote="old"](reply to post at 17:17:09 10/17/20) [/quote]

Pulled NGK' out of it Tried Champ L90C and Autolite 425 All 3 had the same results

Thanks

 

[old]

Try one or 2 grades hotter plugs and see if that helps

 

[WNM]

(reply to post at 08:06:54 10/18/20)

Will give it a try Keep you posted
Thanks

 

[bc]

I don't know but black soot on the plugs makes me think of an exhaust valve or timing issue. A rich fuel mixture will usually leave a black wet looking plug.

 

[old]

I've seen a plug both ways wet or sooty. Sooty just means the plug is still firing. Wet means the plug is gas fouled and not firing

 

[WNM]

(quoted from post at 08:06:54 10/18/20) Try one or 2 grades hotter plugs and see if that helps

Wanted to get a few hours run time before posting a reply Went one step hotter and installed a hotter coil to go along with the electronic ignition that was in there Definitely an improvement

Thanks for the help