Gas? Air? Mixture?!? HELP!! lol (Full Version)

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Gas? Air? Mixture?!? HELP!! lol

  

drewski120 -> Gas? Air? Mixture?!? HELP!! lol (4/6/2008 9:13:46 PM)

OK the 1974 K5 blazer, 383, RV cam, flathead pistons, new ignition system(coil, distributor, and plugs/plug wires), and a 600 CFM Carter AFB performance series carburetor...

Problem im having is starting, when i pump the gas pretty good it WILL turn over, but unless i keep just the exact right amount of pressure on the gas pedal it will do one of two things...backfire loudly(which includes fire exiting thru the carburetor, NOT GOOD im guessing)...is this a mixture issue or what?

Is there a troubleshooter i need to follow or what? lol

Thanks for the help


  
BigBlack73 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/6/2008 11:38:18 PM)

the backfire would most likely be from the carb gettin loaded up a bit. i would say your gettin to much air to your carb, considering you have to give it an equal amount of gas to go with air for it to start. almost like the carb isn't choked enough when first starting it. if it's automatic choke, then your getting the correct amount of air, your probably just getting not enough gas. which could mean your idle is set too low, or your fuel pump is gettin worn out. if it's manual choke, make sure it's choked enough when starting it. if none of this has made any difference, i would, as said before, mess with the idle a bit and see what happens. shoulda got a edelbrock 1400 series ;) lol.

swartlkk -> RE: Gas? Air? Mixture?!? HELP!! lol (4/7/2008 4:31:36 AM)

I would venture a guess that this has to do with your timing post as well.  Intake backfires can be caused by having the spark too advanced.

If you are having to hold the throttle open a bit, I would have to wonder what your choke fast idle is set at and if it is proper.  You may have to pump the carb a bit to get some fuel into the intake, but you shouldn't have to hold the throttle 'just right' to get it to start after that.

drewski120 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/7/2008 1:52:05 PM)

It is a manual choke, gonna try some of the stuff mentioned and will post back...lemme know if you think of anything else please.

Thank You



drewski120 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/7/2008 9:12:40 PM)

Ok so i tinkered with it for HOURS today...i put the two adjustment screws on the front alllll the way in and tried to start it and then just slowly took the screws out half a turn at a time trying to get it adjusted but i just cant get this thing to stay running...i was going to adjust the idle but this carb has the wierdest throtle cable in the world and i cant figure out how to adjust the idle...urghhhh headache..

swartlkk -> RE: Gas? Air? Mixture?!? HELP!! lol (4/7/2008 9:22:33 PM)

THIS link may help...  All I could find short of buying a book on the Carter AFB carbs.

drewski120 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/7/2008 9:29:23 PM)

Hmmm thanks Kyle, really appriciate the help...dunno what im gonna do yes but ill just keep tryin i guess.

BigBlack73 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/7/2008 10:13:25 PM)

Damn... sorrry man, if anything else pops into my head i'll definitely let ya know. i'm not familiar with carter carbs at all. 

Chevy Lover -> RE: Gas? Air? Mixture?!? HELP!! lol (4/7/2008 10:24:44 PM)

I just checked the link that swartlkk sent you and I would have given similar answers as #3 & #4.

drewski120 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/8/2008 6:55:21 AM)

The biggest problem i'm having right now is the truck wont even run at idle...so i cant adjust the carb at all with knowledge of how the engine is running at each setting...so its all guess work really...I've considered a new carb but i really dont have the money for all that right now, one thing i noticed thats odd to me and once again makes me think its gottttta be a idle adjustment...if i get it to turn over and hit it hard on the gas, talkin like 2000 rpms, it will stay going(doesnt really have a choice right? lol) but that just does not seem right at all...but granted im a 17 y/o self-taught mechanic here so my skills/experience, is very limited...thanks again for all your helps guys.

swartlkk -> RE: Gas? Air? Mixture?!? HELP!! lol (4/8/2008 9:23:41 AM)

Base settings on most carbs are 1.5 turns on the mixture screws on the front and screw the idle speed screw all the way in (fastest idle).  This should get you running.  If not, try playing with the timing by rotating the distributor and see how that affects things.

drewski120 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/8/2008 1:22:56 PM)

OK got her to run, thanks everyone for the help, especially Kyle on that last post, i was adjusting the wrong screw for idle which explained SOOOO much(i felt really stupid)...anyway now i've got a loud squel/squeak from under the hood(I mean realllllly loud too) checked oil, its good, so im thinking its the belts, concur? disagree?

Thanks again!

swartlkk -> RE: Gas? Air? Mixture?!? HELP!! lol (4/8/2008 1:35:56 PM)

Remove the belts and see...  For testing purposes on a cold engine, the belts are not necessary.

drewski120 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/8/2008 2:54:19 PM)

K its not the belts...the squel SEEMS to be coming from the carburetor or carb area...

swartlkk -> RE: Gas? Air? Mixture?!? HELP!! lol (4/8/2008 3:10:10 PM)

Is it a cyclic squeak sound or is it more like a whistle?

drewski120 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/8/2008 3:12:00 PM)

Well...i would say more like cyclical but it just randomly started doing this so im not really sure...friend says it sounds just like a pig squealin lol

drewski120 -> RE: Gas? Air? Mixture?!? HELP!! lol (4/12/2008 7:25:24 AM)

Ok so i finally got her to start...now im hearing a LOUD squeal from the engine compartment(can be heard in the cab)...I checked the belts, its not them...a friend says its coming from the carburetor, which it could be but thats odd no?   Well any tips or advice would be appriciated
 
1974 K5 Blazer, 383 stroker, new ignition system, Carter AFB 600 CFM 4-barrel carb.

swartlkk -> RE: Gas? Air? Mixture?!? HELP!! lol (4/12/2008 7:31:32 AM)

Can you narrow down where it is coming from?  The only sound that would be cyclic would have to come from the rotating assembly (NOT GOOD) if the accessory drive belts are off.

Without a better description, it is VERY difficult for any of us to pin point the problem for you.  We depend on your description to diagnose the problem.  You really need to go over the engine with a long screw driver, handle to your ear, other end touching on various components of the engine while its running, trying to find a location that has the noise you describe.

  

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