Need carb help bad....please please

[ooimpalaoo]

1971 k10 4bbl edelbrock carb small block 350. OK so truck runs fine in town. Get it on the highway and it starts off pulling hard then starts to ummmm act like a choke is on is the best way of putting it. My carb is electronic choke and it's not hooked up. I tried using carb cleaner adjusting the carb. I ran in the idle mixing screw on the right side and nothing....all the way out to the point that I was worried it was going to fall out still nothing. ..whats going on ? Please help me out. Any thoughts ?

[Tom Vogel]

Change your fuel filter.

[geezer#99]

Could be filter. Easy to change.
Likely fuel pump is dieing, you have too much fuel pressure, or not enough initial timing.

[ooimpalaoo]

Filter was the first thing I did

[zosoppp]

If it is an electric choke model and the electric choke is NOT hooked up then it will indeed act as if the choke is on when it should not be.

You can run an 18 Ga wire to one of the "IGN UNFUSED" terminals in the fuse block to the electric choke and then the other choke terminal is grounded to the block/carb.

[ooimpalaoo]

Why would the fuel pump work ok to idle and low speed but not on highway? ...by low speed I mean in town. And it pulls hard. When I say pulls I mean puts you back in your seat. Lots of power.

[ooimpalaoo]

Ok I will hook the choke up . But this was never a problem befor without it being hooked up.

[Jrainman]

As per endelbrock instructions , pull top of carb off adujust float height using 7/16 drill bit ,pull adjustment screws out blow the ports out with a small amount of compressed air, run adjustmenscrews back in then 1.5 turns out starting point, clean bowl and power vents , put top half of carb back . start engine and adjust carb after warm up...

[geezer#99]

Originally Posted by ooimpalaoo

Why would the fuel pump work ok to idle and low speed but not on highway? ...by low speed I mean in town. And it pulls hard. When I say pulls I mean puts you back in your seat. Lots of power.

Because you need a load on it.
But it likely isn't that if it pulls hard.
More likely too much fuel pressure. Eddy carbs don't like more than 5 psi. At higher rpm your pump might be putting out too much pressure.
Can you adjust either mix screw all the way in without it quitting?
What's your idle rpm?
What's your initial timing?

[ooimpalaoo]

I can turn the right side all the way no response. The left side all the way in and you can just barely hear it start to stall out but I'm talking just barely. As far as timing I'm not at my shop so I can't say. I will check it. But it hasn't changed and was working fine befor. This came out of nowhere. Idle rpm I have been changing.

[geezer#99]

You're idling on the power circuit. You've totally exposed the transfer slot. That's why the mix screws have no effect. You need to get the throttle closed to fix that. You'll need to increase your initial timing (idle speeds up) and then turn down the idle on the carb
You'll likely also need a fuel regulator set at 5 psi.

There's some info here on transfer slots.
http://www.crankshaftcoalition.com/w...EI_distributor

[ooimpalaoo]

How did I expose it? What could I have done to do this? ..I checked the link it looks like your right on. I'll try it out

[geezer#99]

You've likely had it set like that for awhile. To get a smooth idle you've cranked up the idle speed which uncovers the slot. More initial timing speeds up the idle so you can keep the throttle closed.

Some more stuff.
http://www.badasscars.com/index.cfm/...d=76/prd76.htm

[ooimpalaoo]

Ok so I know I have asked again and again but why was it ok befor. This came out of nowhere.

[geezer#99]

Time!!
Weather! Ambient temp, air pressure etc.
Crap in your fuel!
Bad fuel!
Change of fuel! Winter fuel maybe.

Timing changed!
Motor wore out a bit.

Or just a cantankerous carb.

I've had motors that ran good today and then don't the next day when you want to go to the car show.

[ooimpalaoo]

Gotcha. I'll start with my timing tomorrow. So from reading the link you posted changing my timing will change the position of the throttle blades? If that's right how does that happen? Lol sorry for all the questions I want to know about this stuff

[geezer#99]

Well, sorta!
More initial timing speeds up your idle. Your motor runs more efficiently.
THen you turn your idle back down with the idle screw and adjust your mix screws for the best idle and highest vacuum.
And at your elevation (1000 feet) you need more initial timing too. You need to light the fire sooner due to reduced air. You have a richer fuel vapor that takes a bit longer to ignite.
I usually run at least 14 initial on stock motors at sea level. At higher elevation you might need up near 18 or more depending on your cam. Make sure you plug off the vac advance to the dizzy when you set your timing.

Once you bump your timing up, test for pinging up that nice hill going south out of the city. Leave the vac advance plugged off for that test.

[HO455]

Changing your timing won't change the position of your throttle blades. Change the timing so your engine idle speed goes up. Then you will loosen the idle set screw on the carb to lower the idle speed back to normal. Your the one moving the position of the throttle blades lower. This will drop the edge of the throttle blade below the idle transition slot and then your idle screws should have the ability to change your idle quality. The photo shows the bottom of the carb and most likely yours is like the bottom photo.

[swamp rat]

One of the reasons people tend to adjust the idle screw above the idle discharge port is that bad fuel has plugged the idle circuit's causing the truck to not want to idle, then they end up turning in the idle screw not knowing what caused the truck to not idle. One thing I like to do is to pull the air fuel screws one at a time then take a can of carb cleaner and stick the red tube down the port until it seats, hold it tight with your fingers at the carb body and give it a shot of cleaner, look down the carb and see if the cleaner is coming out of the idle discharge port, replace the screw by turning in until lightly seated then back out 2 turns, then repeat on the other side.

I have done this a number of times and it cleans out the gunk in the passageways, I even used WD40 once.

[demian5]

Originally Posted by ooimpalaoo

I can turn the right side all the way no response. The left side all the way in and you can just barely hear it start to stall out but I'm talking just barely. As far as timing I'm not at my shop so I can't say. I will check it. But it hasn't changed and was working fine befor. This came out of nowhere. Idle rpm I have been changing.

I had a bad booster causing a vacuum leak that caused me to raise idle too high and mixture screws adjustment did not effect idle.

[68Stepbed]

That's why I hate Edelbrock carbs. Every one I ever owned did that exact same thing as soon as the 90 day warranty ran out. I hate to be Captain doom & gloom, but I'll never own anymore Edelbrocks.

[toolboxchev]

Fuel pump pressure and function at WOT is second on the list of checks.....

[ooimpalaoo]

Did what swamp rat said. Now it will stall out when I adjust the needle all the way in. Guessing it had some **** in the seat that wouldn't let it seal. Could my problem be a leaking carb gasket? Just noticed fuel on my intake right now when I was messing with it. I don't get to the shop till tomorrow. I'm still doing timing.

[jescates]

I have the Edelbrock 1406, chokes not wired, and after sitting five years, my truck is experiencing the same problem. It started out with no fuel to the carb. Pulled the tank and halfed azz cleaned the tank. Pulled fuel sending unit out and found it clogged. The netting over the end was non-existent. Replaced the sending unit and filter and drove the truck for a week with no issues. Then out of the Blue, it started what felt like fuel starving anywhere above 60 mph. Then it started around 40 mph. So I pulled the carb and dismantled it! Low and behold, found a lot of gunk in the fuel bowls and in every orifice. Parts of the carb is soaking in carb cleaner as we speak. Once I get everything cleaned, I am going to rebuild with new gasket kit I got off Amazon. I also just bought a new tank from LMC. Hopefully I will have it all back together for the weekend!

[57taskforce]

Originally Posted by ooimpalaoo

Did what swamp rat said. Now it will stall out when I adjust the needle all the way in. Guessing it had some **** in the seat that wouldn't let it seal. Could my problem be a leaking carb gasket? Just noticed fuel on my intake right now when I was messing with it. I don't get to the shop till tomorrow. I'm still doing timing.

You can spray carb cleaner all around the gasket with it running, if it's leaking you will know. The idle rise quickly if it sucks the carb cleaner up. Fuel on the intake is a recipe for disaster. Get that figured out asap.