Ok car is 67 everything is new. 406 short block 10-1/2 to 1 compression from smeding performance.heads are brodix ds heads.air gap manifold.holley 650 double pumper carb. hooker super competition headers.holley blue electric fuel pump with regulator...could be 90 degrees out pump pedal 2 times start car.it starts right up but then you have to keep pumping pedal to keep it going till it warms up alittle.any ideas why it's doing this.or where to look at.right now all vacuum is locked out all vacuum lines are plugged timming is set ar 12 degrees before TDS
Carb problem where to start?
sandys007
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Ok car is 67 everything is new. 406 short block 10-1/2 to 1 compression from smeding performance.heads are brodix ds heads.air gap manifold.holley 650 double pumper carb. hooker super competition headers.holley blue electric fuel pump with regulator...could be 90 degrees out pump pedal 2 times start car.it starts right up but then you have to keep pumping pedal to keep it going till it warms up alittle.any ideas why it's doing this.or where to look at.right now all vacuum is locked out all vacuum lines are plugged timming is set ar 12 degrees before TDS
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Is the choke plate closed with the engine cold?
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Electric choke, or mechanical (cable) choke? Or no choke at all?
If no choke, then you will have to continue to feather the throttle until the engine warms up.
With an electric or mechanical choke, a properly adjusted choke plate will have 1/8 inch gap when closed. A pump or two of the gas pedal to send a squirt of gas down the throat on a cold engine is all that should be needed to get it to start. Once it starts, the electric choke should begin to heat up its element/spring in the circular housing (has the + and - wire connection plugged in) to start pulling back on the choke butterfly. I'd say before a minute, the choke butterfly should be open all the way, and the fast idle is now off.
On a warm engine, the choke may close a bit (electric choke), but the same process occurs; choke spring/element heats up to open the choke butterfly.
Verify that the wire that plugs into the "+" side of the electric choke connects to a 12V source that is hot only when ignition key is in the on or run position. If it is connected to BATT or the vehicle battery "+", the choke will always be open, as it it getting 12 volts all the time, defeating it being a choke.
If no choke, then you will have to continue to feather the throttle until the engine warms up.
With an electric or mechanical choke, a properly adjusted choke plate will have 1/8 inch gap when closed. A pump or two of the gas pedal to send a squirt of gas down the throat on a cold engine is all that should be needed to get it to start. Once it starts, the electric choke should begin to heat up its element/spring in the circular housing (has the + and - wire connection plugged in) to start pulling back on the choke butterfly. I'd say before a minute, the choke butterfly should be open all the way, and the fast idle is now off.
On a warm engine, the choke may close a bit (electric choke), but the same process occurs; choke spring/element heats up to open the choke butterfly.
Verify that the wire that plugs into the "+" side of the electric choke connects to a 12V source that is hot only when ignition key is in the on or run position. If it is connected to BATT or the vehicle battery "+", the choke will always be open, as it it getting 12 volts all the time, defeating it being a choke.
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344 Posts
Does the carb have a choke?
Thats half or probably most of the problem. Hook up the vacuum advance and see what happens. I bet most of your problem will be gone. You will have to readjust the carburetor but once you get it dialed in I bet you will be surprised.
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I am new to carb tuning at this level, but have learned this much about chokes. I won't show my ignorance here, but search this forum, there is a boat load of good info on this website.
For the vacuum advance... read the link below. This is absolutely the best info I have seen on this subject. Like @BillK mentioned, hook up the VA, you do need it and may very well fix all your problem. My BPE 383 had the VA locked out and the choke didn't work right when I got it, it idled very poor. I have since replaced the carb. My new carb (780 DP) has no choke, my VA is hooked up, and my engine idles good... Every engine is different, you just have to find what yours likes.
www.camaros.net
What is the "90 degree out" comment about?
Call Smeding, from what I have heard they have a great reputation and make an excellent product.
Side note, they do not offer a 650 cfm carb for the 406 if I remember right, probably a 750dp or maybe larger. 406 Eliminator is a 500+ hp engine full of really good stuff. Once you get it running right I am sure you will be very happy with it.
For the vacuum advance... read the link below. This is absolutely the best info I have seen on this subject. Like @BillK mentioned, hook up the VA, you do need it and may very well fix all your problem. My BPE 383 had the VA locked out and the choke didn't work right when I got it, it idled very poor. I have since replaced the carb. My new carb (780 DP) has no choke, my VA is hooked up, and my engine idles good... Every engine is different, you just have to find what yours likes.
Timing & Vacuum Advance 101
As many of you are aware, timing and vacuum advance is one of my favorite subjects, as I was involved in the development of some of those systems in my GM days and I understand it. Many people don't, as there has been very little written about it anywhere that makes sense, and as a result, a lot...
www.camaros.net
What is the "90 degree out" comment about?
Call Smeding, from what I have heard they have a great reputation and make an excellent product.
Side note, they do not offer a 650 cfm carb for the 406 if I remember right, probably a 750dp or maybe larger. 406 Eliminator is a 500+ hp engine full of really good stuff. Once you get it running right I am sure you will be very happy with it.
No choke on this one..every other hotrod I ever had pump pedal couple times turn key starts up .couple times feathering gas pedal car would idle and be good.didnt know if jets in carb are to small or anything primarys are #67..None of my other weekend cars ever had chokes either. I never start them in winter or when it's cold so never needed a choke
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Apparently you have to with this car, so just work the foot a little or get a carb that has a choke.
I just had my car doing exact same thing. Mine different engine, but doing same thing.
In my case, I had my 4 corner idle screws each at about 1-1/4 turns out. When cold it only ran off accelerator pumps. I put the 4 mix screws 2 turns out. That fixed it. I still need dial carb in better but I needed more fuel. When cold being lean had a more noticeable effect.
In my case, I had my 4 corner idle screws each at about 1-1/4 turns out. When cold it only ran off accelerator pumps. I put the 4 mix screws 2 turns out. That fixed it. I still need dial carb in better but I needed more fuel. When cold being lean had a more noticeable effect.
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There's alot of overthinking here. Cold engine/no choke plate=throttle feathering till its warm.
Not always, when a carb is tuned correctly it should run well even cold. Not arguing with u, cause most of the time we have just deal with and accept it. When a motor is only getting fuel from acc pumps it’s getting none from the idle circuit. Turning idle up won’t help. Everyone so far has been correct, timing, choke, it all matters. You can’t tune the motor if u can’t get out of the car cause you have to keep pressing the pedal.
In my case the idle mix screws turned off too much fuel. Increased timing helps , but with 12 degrees it should idle. Turn the idle up higher, it should get fuel and not need the acc pump.
It can get technical I had a lot of help from a guy way better with carbs than I am. The Transfer slot exposure needs be correct also. The rear transfer slot, I bet needs a bit more opening this will put the idle circuit in play. A choke up top certainly helps. By closing off the air it increases vacuum and pulls the fuel needed to run.
low floats won’t help. Higher fuel levels Inside the bowls help feed the motor.
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