Batass

Buddy just picked up an 88 rs with a 77 chevelle 350 in it. Stock heads, performer intake, decent cam, and a 1405 edelbrock.

It runs the best so far with the right screw all the way in and the left screw all the way out. Float level is good, top gasket is good. The carb was supposedly just rebuilt and the top gasket looked newish.

The idle comes up with any of the vacuum hoses off. I don't know much about these carbs. It also has an adapter plate from spreadbore to squarebore.

It runs rich throughout the rpms. Timing has been set with a vacuum gauge.

Any ideas?

//<86TA>\\

iTrader: (14)

have you re-jetted it at all? that would make it leaner

Batass

No. I wasn't sure if the metering rods would make it idle richer too. The thing burns my eyes at idle.

If they would, I'll pull em, see what they are compared to "stock" and make a change.

I'm just confused why it would run best with one screw out and one screw in. Black smoke comes out the exhaust on the side that the screw is out, so its obviously too rich, yet the motor likes it there.

TG Goose

you cant run the carb that way. You need to download the 1405 carb manual and take the time to read it FULLY. both those screws adjust ONLY THE IDLE and they should be set almost identically. Start by screwing them in fully, them turning them out 2 full turns, that should put it close to factory settings. the tighter they are, the leaner you will make it, BUT ONLY ON IDLE! Use your vacuum gauge to adjust idle, turning one screw at a time, but both screws have to end up almost identically. You shouldnt have to stray far from the stock setting.

To make the car leaner, you will have to pull the metering rods and jets out to see what you have in there currently. In the 1405 Manual you downloaded, you will find a chart showing metering rod and jet changes possible to go leaner or richer. Using that chart, you will be able to get the carb running perfectly.

Dont worry about being leaner/richer on idle. You can make the carb with any rod and jet combo idle perfectly, so only focus on cruise and WOT metering rod and jet changes.

Batass

I used a vacuum gauge and started at 2 turns out. I've done it four times in two days. The engine IS rich at idle, so there is a problem. The carb likes to be lean on one side, and likes to be rich on the other.

Since any metering rod/jet combination doesn't affect the air fuel ratio at idle, then there is a problem, and what the metering rods are is moot. I read the manual.

I'm wondering if there is an internal leak or a problem with the adapter/base gasket. I noticed that fuel was slowly draining from the float bowls when I had the cover off.

TG Goose

you will have to rebuild the carb then. check to make sure that rods and jets are the same on both sides of the carb. These are very easy carbs to rebuild, I would start there, rebuilding the carb back to stock specs and then start tuning.

mooch1

i agree that both screws must be set at the same place, you can't have one screw in and the other all the way out..go to edelbrock.com and they have tech videos and they explain everything...i have a 1405 on my 350 and it runs great and i adjusted it exactly like edelbrock suggests on the tech videos...hope this helps...

Batass

Today I swapped rods from side to side to see if it would change the screw setting, but it didn't. They were stock rods, 7047. I noticed some fuel sitting high in the carb and started to think about fuel pressure. Its using a mechanical pump so I didn't think it was an issue, but I choked the hose and it ran better. I adjusted the screws while choking it and they evened out from side to side. So tomorrow I'm either going to check fuel pressure, or just pick up a cheap regulator.

I'm not sure if there is still a fuel pump in the tank or not. There are only two wires going to the top of the tank that I can see, one is purple one black. I'm thinking they are for the sender, there's no fuel pump whine when the key is forward.

mooch1

i think you found your problem...i had to get a fuel pressure regulator even with my mechanical pump, it was producing over 5.5psi recommended by edelbrock for optimal performance...i bought an inline fuel pressure regulator off e-bay $15 brand new and installed it on the fuel line going to the carb ,,it adjusts very nice and runs great,,if you have an electrical fuel pump it will be pumping way too much fuel for the carb to run nice,, check your oil, it may have some gas in it because the gas wasn't all being burnt properly,,once you do this , you will see a huge difference in the way your carb and engine runs ...let me know..

five7kid

iTrader: (14)

Set the timing with a timing light.

Recheck your floats. If it starts running better with the fuel supply cut off, the floats may just be too high.

But, if the stock in-tank electric fuel pump is running, you will need a return-style regulator, even if you have a mechanical fuel pump as well (unless it's a return-style mechanical pump).

Batass

It has an unknown cam in it and I was worried it wasnt advanced enough, but was right on. I figured I would re-time it once the richness is taken care of.

I checked the floats and they were good, 7/16 gap upside down.

I dont think the pump is in there, between not finding the wires and not hearing it. Also no fuel flows through the filter unless the engine is turning over.

It appears the engine has been running this way for a LONG time. The passenger header is very corroded and a few gaskets leak. One side of the motor appeared to have been running lean while the other side rich. One pipe blows black smoke and the other not. I wonder if any damage has been done to the exhaust valves....

Could be a couple different problems, but I think making sure the fuel pressure is correct would be the best first step, hopefully I'll find out today.

Batass

Picked up a mr gasket adj reg. It idles better, but the screws still affect the engine the same. The engine has better low end torque, but not what it should. WOT still sucks, I don't think I mentioned that, the engine doesn't run well at any rpms, not just idle.

The left bank LIKES to run overly rich. I'm going to pull the plugs and check the ignition, then I think it might be a head problem. When I pull/change the plugs I'll do a compression check.

I don't think this is a carb problem anymore......

mooch1

i hope it's nothing major.

five7kid

iTrader: (14)

If the timing isn't right, the mixture will not be right.

Timing should be set before any carb adjustments are made.

Batass

I set it with a vacuum gauge. Its got a cam in it, so shooting for a specific number wouldn't be best way to go would it?

I suppose I should at least check the timing and see where it actually is...