carb dual fuel feed

[tx71smallblock]

no its done this since i rebuilt the top end

[Billla]

Originally Posted by tx71smallblock

no its done this since i rebuilt the top end

This is an important safety tip Something to think about in the future, it's generally best to relate the problem for feedback vs. the symptoms.

I'd strongly suspect a vacuum leak - there are a couple of ways to check for this, but the fastest (IMHO, others chime in) is to use a little starter fluid sprayed around the edges of the intake manifold, including the front and rear. If the engine speeds up, you have a leak.

[tx71smallblock]

at the carb or at the block?

[Olden Days]

That picture shows your choke plate almost closed. Without it being hooked up it wont open all the way and thus you will have a very fast idle and rich running condition. Next time you start it hold that choke open by hand and slap the throttle aand see if it idles down

[tx71smallblock]

ok. so when it is hooked up, it will stay open?

[truckster]

That's the purpose of the electric choke. Once the choke is warmed up, it holds the choke plate open and pulls the fast idle step off.

[piecesparts]

Originally Posted by Billla

I think there's something's fundamentally wrong here; I doubt the carb is dual feed; it's set up to feed from one side OR the other. If this is the ONLY change you made that caused the problem, then I wouldn't look elsewhere - I'd swap it back and see if it goes away.

Actually it is just as much a dual feed as a Holley with a fuel bar on the side and it feeds up to the front and rear bowls. The Edelbrock has it's bowls connected across the back and there ARE two seperate needle valves inside the carb, so there are two bowls but the cross-tie inside is there. The fuel line goes to both sides of the carb and feeds pressurized fuel directly to the needle and seat areas of the carb and it's respective bowl assemblies.

As for you fast idle of 1000 RPM, take a look at your choke assembly. Is it an electric choke or a manual hand pull type? This will need to be at the furthest point forward as the engine is warmed up and the choke is not needed. The electric choke can be adjusted by taking the 3 screws on the "BAKELITE" housing and loosening them slightly and rotating the spring housing forward to take the pressure off of the choke plate.

Now, take a look at the driver's side of the carb, just behind the throttle linkage swivel point. There is a cam piece there that is acutated by the choke assembly. It swings up and holds the throttle open to WHATEVER point the "FAST IDLE SCREW" on the throttle linkage assmebly is set at. If that cam lobe is setting at a point where the idle screw is holding your throttle open, then adjusting the idle screw will not make a difference. IF the choke cam is not being held there, due to the choke assembly not being adjusted right then you will have to adjust the fast idle screw. To adjust this "FAST IDLE" screw, you have to turn off the motor and then manually take the throttle linkage to full open--now oyu can see the fast idle screw on the underside ot he throttle linkage. Turn that screw outwards and then restart the engine. Now you will have to set the nromal idle screw to keep the motor running.

I set my choke assemblies to run my truck's fast idle at around 1500 RPM when it is really cold and then at slightly warmer temps the choke cam is staged or stair stepped to allow lower fast idle RPMs. I idle my trucks at 900 RPMs in neutral and that gives me a good idle when in gear. All trucks have the Edelbrock design carbs on them and they are easy to deal with.

[tx71smallblock]

and after all that, what about the timing? should i put it at 0* or leave it at 15* btdc? and when, before or after i adjust the carb?

[Ron 586]

That's new to me. Guess I've been away to long.

[piecesparts]

Why would you want to set the timing to the "0" setting? The engine that you are working on is timed at a "BEFORE TDC" setting and should stay there. The engines that are timed at "0" zero, are ones that are computer controlled and need to be there, because the computer takes care of the advance features. If you are working on a motor that has a standard distributor (preferrably an HEI dizzy and not a computer controlled one) and an aftermarket carb, then you want to set your timing at a point that the engine idles good, runs smooth and does NOT knock or ping on acceleration or under load conditions.

I understand that by your comments, that your distributor is set at 15 degrees. Now I have to ask you, is the vacuum hose STILL connected to your distributor advance "POT" while you are getting this reading? If so, then you need to pull the hose off of the POT and plug the hose, so that you can properly set your timing. With the hose off, the timing should read somewhere around 6 to 8 degrees on a factory tuned engine. For the basic setting, I usually set mine at 12 degrees BTDC and then tighten the distributor locking bolt. When you hook up the vacuum hose to the distributor again the timing marks will move around the dial again and probably out of sight--that is good--that shows you the vacuum advance feature is free and operating.

Steps to get this tuned.

1. Adjust the carb to get the engine to idle smoothly. (not to fast, though)
A. Set the idle at about 700 RPM
B. Set the idle air mixture screws to get the best idle speed at whatever idle setting you choose (usually around the 700 RPMs)
2. Set the timing on the distributor to about 12 degrees BTDC.
3. Next ensure the vacuum hose is back on the dizzy.
4. Re-adjust the idle air mixture screws once again, to trim them out.
5. Check your timing setting for a final verification (remember to pull the vacuum hose off of the dizzy for this).

[tx71smallblock]

thanks alot guys!! i will try to work on it this weekend ( its fn cold). will keep yall informed!