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ok. its a 1975 chevy 1/2 ton pickup with a carburated 350. its getting spark and great compression. it smelled like it was getting way too much gas at the carb, so we adjusted the air/fuel screws. now it is getting less fuel but still wont start. it tries to start but it wont. please help. any input would be greatly appreciated.
More info needed. Was this a normally running vehicle that developed a problem, a vehicle that has just had work done (for example, new upper end that you installed), or one that used to run fine, sat for awhile, and now when you are attempting to start it has this problem?
*If it's flooding when you try to start it, you can turn the idle mixture screws in all the way and that still isn't going to be enough. Stuck float? Initial idle setting high enough?
*If you've completed work and it wont start, is your base timing correct and along this line, any chance you've got the timing off 180 degrees?
*Does it even bark when you try to start it?
it was a daily driven vehicle and then one day it started running like crap but he could still drive it a little bit. and finally it completely quit starting. no motor work at all. we already messed with the idle screws. its getting fuel and spark. has excellent compression. it just wont start. has a recent tune up (plugs, wires, air filter) has a quadrajunk carb. could it have possibly skipped timing? would it still run with skipped timing?
Pull the plugs and get a reading. If the excess fuel is the problem, the plugs should tell you so. If the plugs are gas fouled, then look for a problem in the carb, like a float that has sunk or a bad needle/seat valve or maybe a blown power valve.
1. Jack up the air cleaner
2. Push the truck out of the garage
3. Push a Ford under the air cleaner
4. Tighten the air cleaner
5. Fire it up.
Just kidding. No harm done - right.
On a more serious side, you've got plenty of good advise here, make sure you check them all. Also, if none that worked, ensure your timing is close (like the others eluded to). If you've gas, good spark and compression - it WILL fire (providing the timing is close). To get the timing close, make sure #1 cyl is at TDC and the rotor is pointing toward the #1 plug wire. Get it running again, at least crappy, then you can start blaming the carburator.
well we pulled the plugs and gave them a good cleaning, put them back in and he cranked it as i turned the distributor and she cranked over finally. we are going to get a timing light to get it right but it is running decent for now. thanks for the advice guys.
Don't give it the chance to break. That can be a pita. Replace it as it's more than likely the original, and there is probably a missing tooth on the cam gear.