starting new ls6 motor- few questions/help rqd
12-18-2008, 08:35 AM
#1
starting new ls6 motor- few questions/help rqd i'm trying to start up a new build (ls6 short motor) for the first time, with 243 heads /mild cam/gmpp intake/msd6010 and demon 750cfm mech carb.
its on mineral running in oil as recommended by builder (weber race) and obviously is fairly tight being a new engine. i have cranked it over in bursts (without firing it up) to build oil pressure, which came up fairly easy without spark plugs in to help it turn over. the msd box was turned off so it couldnt fire up. we have the oil pressure light out and pressure showing on the pressure gauge, and it turns over without any issues/noise etc.
however i couldnt get it to fire properly last night when i put the plugs back in and hooked up the msd box. i've had a spark showing on the spark plugs, and its "almost" firing but not quite. i probably need a few tips to help it fire with it being on a carb and not having a chhoke/cold idle enrichment.
normally it used to need 2 good throttle squirts and then a light throttle opening to get it to fire from cold on the old engine. i havent flooded it (plugs arent wet) and its trying to fire, but not quite there.
all the petrol etc is fine, the carb sprays fuel in if you open the butterflies etc.
its a mechanical secondary carb (race car) so i expect it to be a b***h anyway, and i think its just the general tightness of the new engine as the starter is only just cranking sufficient to get the msd box to fire.
i rigged up a second battery and jump leads, we got it turning over much better, but it still wouldnt catch, just the odd attempt.
i had the airfilter off so i could see the carb working, and i was trying it without headers on as a quick test to see if it would fire.
i've been told that putting the filter on or part blanking off the air into the carb may help to richen up the mix, should i also need the headers on for back pressure?
i did also try taking some timing out to make it easier, anyone suggest a good figure for cranking/starting? used to be about 18degrees.
i'm certain there is enough fuel in the carb, and the cam/crank sensors are in (wouldnt spark without them being right).
so any old school tips for me please? :-)
ps its cold here at the mo, 3 degrees c which doesnt help it all either. i was thinking of pre-warming the oil to lighten the load also.
its on mineral running in oil as recommended by builder (weber race) and obviously is fairly tight being a new engine. i have cranked it over in bursts (without firing it up) to build oil pressure, which came up fairly easy without spark plugs in to help it turn over. the msd box was turned off so it couldnt fire up. we have the oil pressure light out and pressure showing on the pressure gauge, and it turns over without any issues/noise etc.
however i couldnt get it to fire properly last night when i put the plugs back in and hooked up the msd box. i've had a spark showing on the spark plugs, and its "almost" firing but not quite. i probably need a few tips to help it fire with it being on a carb and not having a chhoke/cold idle enrichment.
normally it used to need 2 good throttle squirts and then a light throttle opening to get it to fire from cold on the old engine. i havent flooded it (plugs arent wet) and its trying to fire, but not quite there.
all the petrol etc is fine, the carb sprays fuel in if you open the butterflies etc.
its a mechanical secondary carb (race car) so i expect it to be a b***h anyway, and i think its just the general tightness of the new engine as the starter is only just cranking sufficient to get the msd box to fire.
i rigged up a second battery and jump leads, we got it turning over much better, but it still wouldnt catch, just the odd attempt.
i had the airfilter off so i could see the carb working, and i was trying it without headers on as a quick test to see if it would fire.
i've been told that putting the filter on or part blanking off the air into the carb may help to richen up the mix, should i also need the headers on for back pressure?
i did also try taking some timing out to make it easier, anyone suggest a good figure for cranking/starting? used to be about 18degrees.
i'm certain there is enough fuel in the carb, and the cam/crank sensors are in (wouldnt spark without them being right).
so any old school tips for me please? :-)
ps its cold here at the mo, 3 degrees c which doesnt help it all either. i was thinking of pre-warming the oil to lighten the load also.
