So I have ordered my first ever Edelbrock carburetor for anything. It's going on my 1986 GMC C3500 with the 454. The old quadrajet (or should I say quadrajunk) has gone out on me. I ordered the Edelbrock #1406 Performer along with the adapter plate #2696. Installation went well except for the fact I dropped one nut and it disappeared into the deep black hole that exists in these trucks. Anyways, my fuel pump is not pumping well, so I dumped fuel in the line until the fuel filter was completely full. Also dumped a small amount in the throat of the carb. I went to start it and the thing was constantly popping and backfiring until it ran out of fuel. I tried it again and same thing happened. I haven't tried to adjust anything on the carb yet. Can anyone tell me what could possibly be going on? Sounds like its flooding out, but the engine stays running as long as the carb is getting fuel.
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Did you set the mixture screws to the factory setting, turning them in, until they just touch, then 1.5 back out? Your choke could be too tight as well. Mike's Carburetor Parts on YouTube has several different videos on setting up carburetors.
Also make sure your spark plugs are in tightly, if you have changed them recently. I did them on my '79 Catalina last year and noticed a few months later I smelled gas under the hood and intermittent backfiring. The plugs had worked their way to being slightly loose. I used Mike's Carburetor Parts' videos to get the choke on my '79 Catalina just right. Car started at 5 degrees F last year. Scotty doesn't do many videos on carburetors. That's understandable, they're not exactly common these days.
Change the fuel pump if it's not pumping fuel properly. Unless they started putting electric pumps in the tank around that time, the fuel pump is attached to the block and should be pretty easy to get off.
Just re-adjusted the fuel mixture screws to 1.5 before I saw this answer. One was 2.5 and another 3.0! Way too much fuel. After adjusting and trying again, the engine ran a lot better until the carb ran out of fuel. Gonna check the fuel pump, but I can probably tell you its gonna have to get replaced. It has a mechanical pump on the left side of the block if you're looking at it from the front of the truck. Appreciate your answer anyways. Glad you said something about the spark plugs. I did check those a couple months ago and will make sure they're in there good.
I usually start the mixture needles at 2.5 turns out and turn them in after the engine is running to fastest and best idle. You need fuel pressure in the float bowl to keep the float at the proper level and the float needle in the right place. Check with Edelbrock for correct fuel pressure for that particular carb. Some are pretty sensitive to that adjustment. Good idea to get rid of the Quadrajunk. The new Edelbrock will have all the new Viton seals that won't be affected by the ethanol in the gas.
Had to set the screws 1.5 turns out before it stopped. Did confirm carb wasn't getting fuel. Gonna hook up a secondary tank to see if the fuel pump really is bad. I'm pretty sure it is since the gauge says it has 1/4 of fuel. So far, I am loving how easy it is to tune this edelbrock compared to that Quadrajunk.
Excellent!
Here's the crazy part. I put a fuel line in my little 1 gallon tank, and the fuel pump worked flawlessly and the truck started and ran. That means either the truck tank is empty, or the switch that switches from left to right tank is broken. I'm getting close to getting this truck roadworthy again.
Good, you'll get it.
I'm still having trouble with this. So I figured out it was the right tank that was out of gas. I filled it up and I finally got some fuel going through the lines, so that issue is fixed. Got the choke hooked up (have not adjusted yet). I started the engine, and it idles very rough. It will rev up, but you have to floor it to get it up to probably 4000 or 4500 RPMs. I tried to put it in reverse just so I could back up and cut the grass under there, but it wouldn't move even while flooring it. The engine would stall when I let off the gas. Adjustment screws did nothing even when I leaned them out all the way. I'm lost at what to do.
tried to put it in reverse just so I could back up and cut the grass under there, but it wouldn't move even while flooring it. The engine would stall when I let off the gas.
How long has the truck been sitting? Your brakes could very easily be locked up. When I first started reviving my Catalina, it also would not move. Check the transmission fluid level as well.
Check the adjustment on your base idle screw. If it's too far out, the engine will stumble and stall if you're not holding the throttle open with the pedal. The throttle plate is suffocating the engine, if it's not set right. I had issues with my Catalina getting stuck on the fast idle, even in 90 degree weather. When I got it to finally drop off the fast idle, it did the same thing. It stumbled and stalled without my pressing on the gas.
I managed to get it moved when I did the sea saw movement (going back and forth in R and D). It had sat there for probably a month or 2, and it created ruts deep enough that it would've taken a lot to get it moved even if it was running good.
I've raised the idle screw a lot already. It will stay running when I let off the gas, but its very low rpms and it will nearly stall when its in gear without some gas pedal. What do you mean by "throttle plate is suffocating engine"?
If the base idle screw is set too far out, the throttle plate will start acting like a choke and partly prevent air from going through the carb and into the intake. The base idle screw (the one on the driver's side, furthest to the left) pushes the throttle open when you tighten it, and lets the throttle return spring close the throttle when you loosen it. Opening the throttle raises the idle speed, closing it lowers it. Lower it too much, the engine will struggle to get enough air. Raise it too much, and you could damage the transmission when you put it in gear/ waste fuel. Carburetors are a totally different animal from computerized fuel injection. I learned almost all of this within the past year, I was a newbie to this computer-less car world. Haha.
It sounds like the choke is not properly adjusted and is running much too rich. Is the choke manual, electric, hot water, hot air, what?
I see it is electric choke. Make sure the + is connected to an ignition on 12v source and the - side is grounded.. Did you go through all the tuning steps in the Edelbrock pdf?
I haven't looked at the Edelbrock pdf, but I followed everything in the installation manual. Choke was properly connected. The choke did open when I let the engine run long enough, but the terrible idling never went away. I slapped the Quadrajet back on there, and the engine actually runs the same way with it on there just with a little more throttle response. I really don't know what to say about that, but I'm not sure if the carburetors are the issue at this point.
Got it figured out guys. I checked the spark plugs, and all 8 of them were not within the recommended gap. The gap is suppose to be 0.45 for this engine, but they were all 0.39. Not only that, but they were covered in black. After getting new ones and gapping them correctly, I used the Quadrajunk and started it, and it ran flawlessly. Awesome!
Just for laughs check your ignition timing, it may be way off. Also, re-check all your vacuum lines for correct routing and connections. For example, if you switched the manifold vacuum and the spark port vacuum, it'll cause major running problems.
So I recently installed an Edelbrock 1406 on my Chevy 454. When I started it the first time, I hear a hissing sound that's not really audible in the cabin when idling. I didn't think too much about it, so I went on a test drive. When I gave it decent throttle, the hissing was loud, and when I let off the throttle completely, it was still audible. The hissing disappeared though when I used partial throttle. And then when I floored it, I hear a very loud roaring sound (like it has no muffler or something). One of my customers had a 350 with the same carburetor and it never made these sounds. I have the big tapered hole in the back blocked with the worm screw that came with the carburetor. Is there something wrong or did I miss something? I think the roaring sounds pretty good, but I don't think its normal.