hey guys, like the ***le says my engine wont fire after it has been running. it is a olds 303 with a 6 carb log intake running the outer 4 carbs, center 2 have block off plates.electric fuel pump, filters are clean as a whistle... anyways from a cold start it will fire perfect the second i hit the push ****on and run just fine for as long as i want. once the motor is off. if i try to start it even a few minutes later it doesnt fire at all. it turns over, huffs and puffs at times but will not fire. after about 45 minutes or an hour it will fire, a little more hessitant to fire than from a cold start however. (takes a few seconds to fire up, opposed to right away like when its started cold) if i run it, then dont fire it again until the next day it fires perfectly again. ive tried to mess with the fuel pressure which was pointed out to me but that didnt seem to help me. any thoughts would be great. thanks keith
When you get to the hot no-start condition, try a little squirt of fuel or starting fluid in the working carbs. If it starts momentarily then, it sounds like you're fighting a fuel problem. If not, then it sounds more like electical or mechanical gremlins. Might also check manifold cranking vacuum both with the engine cold and at operating temperature. Solid or hydraulic lifters? Electronic or points type ignition? Does it sound different cranking hot than cold?
hmm. hydraulic lifters, points ignition. i would say it sounds just about the same cranking when it wont fire.
303's were famous for that after they got 40 or 50 k miles on them. The compression droped and they wouldn't start hot. We used to hook two 6 volt battries in series. I don't know if you have the same problem with 12 volt.
These two posters might be on the right track. What Dehartcarl is leaning towards in reality is low compression on an old motor did not have enough vacuum to let the carb work correctly at low rpm like cranking. You have 4 non-progressive carbs with EIGHT throttle plates open which means 8 vacuum leaks. Have you tried running it around, then shutting it off and then try starting with foot off the gas? Try that, no pump on the squirters either at first. If it did not start, try a couple of pumps and take your foot back off to start. One more thing to try with 2 other helpers. Run it around, then back home and have 2 guys hold their fingers over all 4 carbs while trying to start it at 1/4 to 1/2 throttle. Have them leave a very small gap between 2 fingers to let just a tiny bit of air in. see if it fires.
easy test for what is mentioned above. It WILL smoke but will answer the obvious. When hot, pull the plugs. I know they will be hot, but this is for posterity. Squirt a couple pumps of oil in the cylinders from an oil can. Roll them plugs back in and see if it fires with out doing anything else, other than a squirt of gas or so. This test will seal up the rings and determine compression loss or not.
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