Thread: 355 sputter?

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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!

I woulod for sure throw at least a set of headers on there. Please tell more about the motor itself, cam, pistons, heads, intake, and that will give a better picture to build from.

cam specs are Dur 222 INT and 230 EX, Lift is 509 int and 528 ex. intake manifold is an edelbrock air gap, pistons are hypereutectics, compression is 9 to 1, HEI distributor. heads are just rebuilt 85 heads... headers though?? why headers? if you dont mind me asking? ive heard of alot people having a lot of trouble keeping headers from leaking...

Buy a high quality set of gaskets, make sure your header flanges are flat, and you will not have any trouble from a leaky header. Why Headers ?, You will be trapping some of your power by restricting your air flow out. You have increased your air intake by strapping on the aftermarket intake and cam, but you could be defeating your pourpose by cutting it off with stock manifolds.

ok that makes sense.... thanks for the help ... and back to my spark plugs ?? hotter plugs maybe do the trick ? or a combination of both hotter plugs and a tune on the carb?

OK----coldest CHEAPEST sparkplugs, open exhaust at the manifold-----

You need to hook up the exhaust, put in a decent heat range/reach spark plug, check and set timing to spec, check fuel pressure to see the carb isn't overflowing

Originally Posted by chevyguy350

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?