Reading spark plugs,how do you do it???

[DAVID GAGNARD]

O-K; when reading your plugs,just how do you do it????

I have run down the road about two to three miles at a about 2500 to 3000 rpms,shut off the engine coast in the driveway right into the shop and pull a few plugs (the easy ones) to read.....I have changed jets twice today already.... At first I'm too rich,black exhaust pipes,black but dry outer rim of plug,porcelan on plug fairly white,electrode not white,but not brown or black....Car runs good and accelarates good,no stumble or hesitation..... Only jets I have are five sizes smaller,put them in too lean,car idles real well,but when you "get on it" it has a definite stumble for a good two seconds and then it goes,at cruising speed if you step on it it has the same stumble...checked the plugs,electrode very white and kinda powdery looking,porcelan white, outer rim still black....

Now when reading plugs,what do you look at???? Electrode color???? Porcelan color???? Or outer rim color??????

Running MSD box and coil and distributor,motorsport plug wires, tried champoin plugs/autolite/bosch,seems to not make a difference on plug brand,all look about the same....and all plugs look about the same (thank God)....

Also,for a 350 hp,351-W with early iron heads and 10.4 to 1 compression,what plugs should I run???? Prefer either champion or autolite, give me a plug number that you have had good luck with....

Going to get new jets half way between my original ones and last change,should be about right.... Carb is an old (10-15 years old)Holley 600 DP,the only changes on it are the choke and choke horn have been removed and I boiled the carb and rebuilt it with a holley kit,engine runs real good with it,just need to "fine tune" my jetting....Original jetting was 66 front and 76 rear, all I had on hand to try was 61 front and 71 rear,any recomendations?????

Thanks guys;

David

[427 S/O]

David, do an internet search using your question and include the word 'pictures',
much info out there..........