Quote Originally Posted by chevyguy350 View Post
alright newly rebuilt 355 ... plugs show its running rich, now im just wondering if i can get away with going to a hotter plug or if this will need a tune on the carb?? i bought the cheapest (and probably the coldest plugs) i could find... the carb is a Q-jet.... oh and i just recently got done breaking in the cam and i still dont have exhaust hooked up , just coming right off the exhaust manifolds... should i wait and see where the plugs are at after i get the exhaust hooked up? or will it not have much of an effect?
thanks in advance for help, i just dont have anyone around that i can go and talk to about all this so all help is much appreciated!
It will be waaaaay rich once the exhaust pipes go on, IF already tuned for open headers/manifolds.

colder plugs will only foul easier in this situation, so start with a stock replacement plug and tune from there.
You want to have the correct heat range so you are not fooled by the plug reading. The idea is to have 2 threads down from the ring turn color from heat, then get your timing straightened out. You want to see a lil white mark above and below the tang bend on the plug..this tells you have about the right amount of initial and total timing. If you see a white mark down whee the tang meets the ring, you have too much total timing or full advance.

the color is to be read inside,down where the porcelain meets the steel body.
After that... the upper portion can be white'ish and be good.
It's todays gas that does this.

Lets start with.. how much total timing do are you running?