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Truck won't idle after carb rebuild

28K views 56 replies 6 participants last post by  cobalt327 
#1 ·
So I was having major issues with my quadrajet and instead of taking on the daunting task of rebuilding a carb foreign to me in two days I decided to re-jet and rebuild a 650 carter afb I had laying around. So everything went smooth the floats are adjusted properly everything is in right but now the truck wont idle and you have to feather the gas to keep it going. It has no choke as it originally was off a circle track car and it ran fine on my 350 with no choke just a little cold blooded in the morning, but if i stick the choke closed now the engine idles but even if I wait until it hits temp as soon as I open the choke back up it sputters and dies
 
#28 ·
Pay no attention to the NOOB who said get somebody else to do your carb work. I'd extend a welcome to the board to him but I have a feeling a ******** like him won't be around too long for it to matter.

Follow Cobalt's advice and you'll be fine. You ain't the first and won't be the last to have a vacuum leak after changing a top end part.
 
#29 ·
Many autoparts stores will rent you a timing light for free with a deposit. if you're only working on that one engine it makes little sense to buy one. Also check for loose spark pulg connectors at the plug or cap side. Also possible arcing from the plug wires.
 
#31 ·
Ap72, I'm constantly working on something and my dad has two 50's fords he's gonna start on so I'm sure he'll be by to borrow it, 30$ isn't a big deal if I know it'll get used lol. As far as plugs arcing, it could be I can pick up a set tonight at work and try that.

And daddy, I always follow cobalt's advice :thumbup:

The issue I'm having now after purchasing a new pump (that airtex didn't last two weeks) I now can't even get it to fire on its own, yesterday I had it running halfway decent then the pump died, now I have to put some fuel down the carb to get it to fire then I can keep it running but it wont even try on its own and I can see the fuel spraying in.

And malc, I'm 100% positive I've assembled this carburetor correctly
 
#33 ·
Now I'm not so sure I did. I checked everything new plugs and wires ignition control module is fine coil is good pickup coil is fine new condenser good compression, 0 vacuum leaks, base timing 10 btdc 36 with advance hooked up 5.5 psi at the carb, spark is blue... The only possible thing left is the carb. But everything was done per edelbrock specs .095 secondary jets .086 primary jets .065 x .052 rods and the orange step up springs. I mean theres not much more you can mess up in an afb...
 
#38 ·
Sorry if that came out wrong, the only carb I have used is the afb its just a 500 now after I jetted it, and it seems to run a little better the farther I pull the mixture screws out, im talking 4-5 turns but it still surges and runs rough no matter what, and I'm 100% positive I have no vacuum leaks, I used half a can of ether looking
 
#42 ·
You deserve a swift kick in the *** with steel toe boots for that.

You CANNOT "JET DOWN" A CARBS CFM RATING!!!

You're not the first one to think this but its not even close to right. There's your first problem though. Jet it to the proper specs not the specs of a carb you don't have. Actually id use a rod one step thinner on the primary step from stock meaning it it calls for a 7250 run a 7150. I don't know the stock calibration off the top of my head but we'll start there.

Start there and then come back. 90% of your problem should be eliminated.
 
#44 ·
Seriously?! Ap I apologize for all the headache I've caused you, everyone I've talked to including my farther who has been scratching his head over this has not once mentioned that you cant jet down a carb... I've never done it, just rebuilt them. So, and please just bear with me, why is that you can jet up a carb but not down? And how did you find it was a 625? I did a lot of searching that turned up nothing. And am I wrong in thinking carter and edelbrock are one in the same?
 
#45 ·
You can't "jet up" a carb either. Its a common misconception among people who know just enough to be dangerous.

For the carb model you have I just used google. Took all of 13.2 seconds.

The edelbrock and carter designs are VERY simmilar but they are not identical. Most of the parts interchange but not all of them. Also some parts of the fuel metering are different, which is why you can't use edelbrock specs.

Fimd the carter specs, you may be able to match the edelbrock rods and jets to their specs for use in your carb.

Btw you have an easy carb to work with, so just be patient and find your stock specs.
 
#47 ·
Id go one step leaner on the primary section of the rods still. You can measure them with a micrometer if you can't read them. My first carb was an edelbrock 1406, best carb to start with ever.

625 is not too large at all. I have a 1406 on my ford 2.3l right now, runs better than the 390cfm holley did.
 
#49 ·
So I cant get to a part store for a little while so i just put the carb back the way it was and it starts easier and throttle response is much better but it still doesn't want to idle. I have to start it and keep it running with the choke (it doesn't have one) is it normal for the engine to rev up when you close the choke partially? I've neve experienced this thats why I'm asking
 
#51 ·
Yeah everything is plugged and I dont have any vacuum leaks that I can find, I didn't even pull the carb just took the top off and swapped everything back. I'm actually leaving shortly for the bank lol I'm in the process of buying anther vehicle, just a small commuter for work but I can mess with the vacuum some when I get back. Is the choke thing pointing towards a vacuum leak?
 
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