panamacity347

i have a 347 with a holley 670 street avenger is this carb too small or too big i don't know too much about carbs,but when sitting at idle u can smell gas pretty bad would that mean it's running too rich i went down a few jet sizes on the primary jets and it seemed to accellerate a little better would it be a good idea to go down a few more jet sizes or would that make it run too lean. i been trying to tune this thing but i can't seem to get it where it needs to be.

86blackgt

what do the plugs look like?

panamacity347

well before i put smaller jets they looked a little black or dark brown

redemption

no it not to big your fine i have a 750 in my 357 usually a 650 is even adaquate for a 347
mostlikley you need to tuen the idle mixture screws, make sure your float is set right to were its dribbling out of the screw or almost dribbling out.
the way i kinda tuned mine which still isnt really tuned but can still drive it
since i have a 4 corner holley i back them all in then turned them out 1.5 turns each, then when i finally got it idling and at operating temperature with choke off, i would turn one screw until IN until it started to stumble then i would back out 1/4 a turn and i would do this routine to all of them after that its pretty much non gassy smelling but excessivly but its not professionaly tuned you know like at 14.7 a/f that requires tools that i dont have hahaha
aslone as its not running lean like a good friend told me youll be fine
just make sure its not shooting black smoke out that back thats obviously too rich and turning those screws will get you somwere in between were you need to be, theres other ways wich i tried like a vacuum gauge and try to get highest vacuum which sorta worked but since my cam is so big the needle was having a parkinsons disease problem and coulding tell if it was going up or down so i was sol on that idea.

panamacity347

thanx for your help, when i get a chance i'll have to mess with those adjustments. this seems a little weird to me but when i have a low idle about 900 rpm and i floor the gas pedal it backfires really bad in nuetral or under load but when the idle is around 1500 it don't backfire to bad but the power wasn't there until i down sized the primary jets i didn't do anythind to the secondary jets, how can you tell if your running too lean.

redemption

if you take out your plugs and look at them the top of them will be a white or light brown, means ur running to lean, mine are a light black, i havent driven it it long runs because its been over heating so once i drive it more then 10 min i should know if its running to way to rich which i dont think it is . im on the rich side but not tooo rich
check you timing for the back firing

panamacity347

thanx