carb spitting back on startup

[70 R/T]

Need some help with this one,have been having alot of trouble starting my 383 when engine is warm,seems to be ok with cold startup but once engine is warm when restarting wants to spit fuel back ,once it starts seems to run ok,has also been loading up plugs since this started happening,any ideas,bad fuel? power valve problem? float level?,have changed plugs and still the same, any help welcome.

[Chryco Psycho]

it could be the intake is too warm & boiling fuel into the intake while sitting warm , installing a intake gasket wiuth a blocked heat crossover port could help  , it could also be timing , if the engine is cranking slow it may be kicking the piston back allowing the compression back into the intake

[70 R/T]

Thanks C P,think you may be right as engine seems to be cranking slow,which makes sense with kicking back the fuel charge,will check timing also,car was running great until recently,have had a really hot summer here thou,would i be best to bring back the intial timing a few degrees? would this condition of spitting back have damaged my power valve ? am running stock holley list 4218 .cheers

[Chryco Psycho]

yeah back the timing off 2-4 *
 unless it has seriously backfired the power valve will live , if it is rich all the time though you may want to check the gasket , it should be dry in the power valve cavity

[70 R/T]

Will do,thanks CP.

[cudabob496]

check float levels, timing.

[70 R/T]

Have checked float level and seem to be fine,backed off intial timing and is now better,checked power valve and is good,car still running a bit rich i checked jet size and has 64s ,dont think i should go down as this seems to me about the lower limit for a 383,changed plugs from ngk BP5S to champion J12YC have run engine, warmed up and checked and adjusted idle mixture with vacume gauge,still feel engine rich as exhaust very sooty and stings eyes,may consider MSD blaster coil as running stock coil with stock dist,any help welcome,would i need to change ballast resistor with higher voltage coil? cheers

[Chryco Psycho]

rich at idle is usually caused by the cam rich at highway speed / plug color darker than light tan change the jetting
 you may need a lower resistance ballast for the HO coil each coil is different

[70 R/T]

OK,thanks CP,will test drive and then pull plugs to check color,will lean jets if needed ,just thought 64 getting a bit small,sea level here,also have disconnected vacume advance ,,and plugged hose while i am retunning,will get there,have improvement with carb not spitting back fuel charge,i think you are correct about champion plugs,cheers

[70 R/T]

Well after test driving a few times over past few weekends plugs loaded up with fuel,decided to start over with dwell-points gap,checked leads,checked dist cap,carb idle mixture with vacume gauge,and another set of plugs,this time i used rj12yc,also still left vacume advance plugged,reset intial advance,Challenger runs real good again with no carb spit back when starting i think my engine likes the resistor plugs,decided to keep stock coil,need to reset vacume advance to finish,what setting is best to start adjustments inside cannister,have turned back to click with allen key,seems to be about 8-10 revolutons between lower and upper setting,car running nice after test driving would like to get vacume right now for highway cruise economy,cheers Paul 

[71chally416]

If you change a bunch of things when you have a problem you end up never knowing what helps and what hurts.  

[70 R/T]

Yes Your Right there mate  ,i think my original problem was bad fuel and got into checking and ajusting settings,back on track now as car running good again,will ajust up vacume adv cannister by small amounts until i detect hesitation surge at cruise.