Edelbrock 1406 troubleshooting

[red71cheyenne]

How do I figure out what is wrong with my carb on the Blazer? I've checked and rechecked the timing and its right, but the engine wants to backfire and chug under power. I got the carb used and rebuilt it, but don't know a whole lot else about them. The air/fuel needles are out about 2.5 turns each. This is on a newly rebuilt 350 with manual transmission, new skip white dizzy and like I said, I've checked and rechecked the timing and it seems to be set right. Thanks for any help. Jeff.

[Michael Star]

Are you sure both screws are set the same? Best way to find out is to screw them both all the way in and back them out in half turns.

[dukcaln]

mine did the same thing, check the needles... remove them and spray air inside to clean out any obstructions.... turn alll the way in and back out the same with 1/2 turns. Mine like to run at 3 turns out. Also do you have an electric chock...if so adjust the black dial back to factory spek and go from there. Adjust it when it is cold... What is the timing set at? Have you checked for vacuum leaks and have you replaced the fuel filter?

[67chevemall]

Best way to fix that one is to buy a Holley Truck Avenger

$0.02

[piecesparts]

This is applicable to ANY carb, even a Holley. However it does work on Edelbrocks and Carters. To set the air/fuel mixture screws to a proper adjustment, do not do it by the number of turns and listening by ear. Connect a vacuum gauge to the intake manifold or a port that is connected to the manifold and not a timed port from the carb. Then set your idle speed to a comfortable number, like 700 RPM, turn the first screw inward to the stop and make sure the engine continues to run, if it doesn'e then take the screw out to the oriingal setting and set the idle just a little higher. Once the air/fuel mixture screw is all the way in, start turning it outward until the vacuum gauge indicates the HIGHEST vacuum reading that you can obtain. Now do the second air/fuel screw and watch for the same results. Once oyu have the screws at a point of the highest vacuum signal you cna get, do the procedure one more time to get the most optimum setting that you can achieve. Once oyu have done that, turn both of the air/fuel screws inward a 1/4 turn and then you are set for the proper mixture of air and fuel at idle.

If you are getting a back fire, then there are other items that you can look at--first is what do you have your timing set at? You said it was proper, but at what point and did you set it with the distributor vacuum disconnected. Just checking to get to the base level of the trouble. Also what idle speed do you have for your carb setting while in drive, not in neutral, for an automatic tranny.

Check the accelerator pump for which hole the pump rocker is connected to the push rod and see if it is too drastic or not enough pump stroke. Do you know what jets and metering rods are in the carb. Some of your issue could be aligned with the amount of fuel you get at the transition from the primary to the secondary jets. YOu can calculate the bore size by the number stamped on the jets and compare it to the numbers stamped in the side of the metering rods EXAMPLE: jet size .100 minus the rod (needle) number 7045 equals a bore size of .030 on the top and .055 on the bottom as the rod strokes out of the hole. This can be changed and optimized by changing rods or jets. You may have to invest in a couple sets of rods and jets, if you want to change.

One last thing, which color of spring is under the primary needles. That can change how the carb responds to a vacuum signal within itself and help smooth out your transition momsnts. All of this is a little time consuming, but you can tune an Edelbrock to work as good as any carb out there.

[67chevemall]

You know I had that once and checked everything.... it was I crossed 7 and 8 wires

Double check your spark plug wire order.

[geezer#99]

How did you set the timing? Plugged the vacuum line to the distributor first I hope.

[red71cheyenne]

Thanks for the replies guys, the timing is set at 12 before tdc right now, thats about the best it would run. I've tried setting it at all different times to see if it would cure the bogging issue, but it doesn't.

I set the needles the same way you described dukcaln, and like I say, it was about 2.5 turns before she started running rough.

I did not set the needles with a vacuum guage. But I did set the timing with the adance plugged.

I'll check all those things you recommended, piecesparts. This is a manual tranny, but the idle is set about 600 rpm. Its only once I'm rolling and try to accelerate in order to shift gears that it starts its bogging, bucking and backfiring. While its idling, everything seems fine.

[dukcaln]

man wish we can get a grip on this,,,,, is it a manual or electric choke?

[C10_ustacould]

If you call the edelbrock tech line they will help you for free. The Edelbrock carb used metering rods and springs for "jets" and different altitudes, engines, etc will require different rod/spring combinations. I called and talked to one of their techs and he identified the correct combination and even sent me the correct metering rods for free! Great customer service...
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[57larry]

Originally Posted by BucksSS

If you call the edelbrock tech line they will help you for free. The Edelbrock carb used metering rods and springs for "jets" and different altitudes, engines, etc will require different rod/spring combinations. I called and talked to one of their techs and he identified the correct combination and even sent me the correct metering rods for free! Great customer service...
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X's 2

[super72swb]

I to had problems with my 1406 and the problem I found with mine was that it had built up corrison in the bowls. It stop up the chambers in side the carb. It is real easy to tear down and clean. I took my time and was careful with the gaskets when separating the top section etc. I was able to tear it apart reuse all gaskets and it works like the day I bought it. I used wire from my welder to run it through the same port hole then use compressed air to blow them out. Used a little oring lube on gaskets. you would be surprised how easy it is. Friend of mine called me asked if I would help get is sons truck running. Took mine off and placed it on his truck cleaned gas tank put new gas in it fired right up. Took his 1406 apart found same problem. It was easier second time but it fixed his. Just my experience with eldebrock hope it helps you.
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[BIGKEV]

Check your ignition module!

[red71cheyenne]

Thanks guys, like I said, the carb was rebuilt before I put it on, so it was clean as a whistle inside and out. I will try calling Edelbrock and see if they can help me identify the metering rods and jets.

It has electric choke, but I don't have it wired to voltage right now. It doesn't matter if its connected or not, I have the same poor running issues.

As far as the ignition module goes, its a brand new skip white dizzy. Do you think it could be bad? It has less than a hundred miles on it. I replaced the dizzy because I thought it was causing these issues. No change after the swap.

[hatechew]

Did you check your plugs for a crack in the porcelain? You may need to put a tee in the fuel line and put in a good pressure gauge. Not one of the little ones that many people use, but a bigger one. Tape it to the windshield where you can see it. Go run it through second gear and see if you have 5 to 6 psi. If not you have a fuel issue.