Is there a link that shows step by step to changing out the secondaries? I have the new jets and just figured I would jump in and find them.... if I don't find instructions that is..

 

The edelbrock site has the manual. It is just two jets in th bottom of the bowls.

http://www.edelbrock.com/automotive_...ers_manual.pdf

 

Thanks. I remember now.... I printed this up before and misplaced it. Thanks for the fast help!

I ordered new secondaries as my Vette falls on it's face when I get into it, Edelbrock said to reduce the secondary size. Not sure why I am having to do this... It is a used Carb, very nice though. I would think the 600 CFM should be a nice fit to the 350 and not need smaller jets.

 

It is a 1405 in a 1988 350 from a GMC truck in my 69 vette.

 

Explain falls on it's face? Does it put out black smoke out the pipes the whole time you are open throttle?

 

Yes... Black smoke, even though timing has been checked. It idles fine. You take it out on the road or try to get into the carb in the driveway and it loads up. If you take off from a complete slowly, no problem, you try to get on it and is dies out, no power, speed and blows smoke and putters.

 

Your problem sounds more like a vacuum secondary flapper plate failing to open or the choke. Because it was running previously in a pickup right?

 

are you planning to change the primary jets, primary rods

or secnodary rods?

never mind, if it's an edelbrock carb, non Qjet, I don't know anything about it.

 

Sorry,,, I should have clearified. The 350 came out of a 88 GMC. Since I was putting it in a 69 I removed the intake and Fuel injection carb and installed a Edelbrock Carb and intake as recommended by them. (I bought off e-bay from seperate guys though) I thought about the Vacume but closed that idea as I blocked all Vacume inlets to carb and it did the same.

I was told Edelbrock to change the secondary to .92 from the stock .95, that is assuming the previous owner didnt change them in the first place. I will know in the AM as that is my first project of the weekend.

 

This is the site you want. Everything you ever wanted to know about the Edel carb (really mostly a Carter AFB).

http://www.telusplanet.net/public/gi...delbrock_1.htm

 

The first step with a used carb is to return everything to a known starting point, i.e. edelbrock's factory jet/rod sizes.

Get a copy of the instruction manual from edelbrock's site and go through all the settings and make sure they're good. A float that's mis adjusted can cause a multitude of problems, running rich (black smoke indicates a very rich condition) being one of them.

From there, edelbrock includes a nice chart of various jet and rod combinations and explinations on how to tune their carb.

Chris

 

Ok. I put the .92 jets in as recommended by Edelbrock. It no longer bogs down when I get into it, but it does still blow some black smoke, and back fires a bit. I assume I need to readjust the timing and adjust the screws in front a bit, right? Running too rich? I should back out the screws, right?

 

UPDATE: Took the lady around the block and seems to be doing fine. No backfiring (must have been all the old gas or whatever) and black smoke seems to have died off too. It just came to me as I was typing this that the black smoke could have been oil that seaped by the seals, kinda odd since I had this motor torn down and put all new gaskets and seals in her and had the Valves reseated....

None the less.... She is running well enough I'm not scared to take her out of town, but I can't go too fast, still needs all new bushings, the ones on her are from the factory.

 

Not as powerful as I thought..... I need to print those instructions from that link (Thanks for the link!) and see what I can do... I don't have that gauges they are taling about though

 

In is leaner.

 

So... I turn the screws in to get rid of black smoke? Thought I would turn them out....

 

Correct

 

Those screws adjust idle mixture. They affect the mixture at other throttle positions, but less and less as the throttle opens.

Black smoke is fuel. Light bluish smoke is oil, so I would say that it's not oil you're seeing burn.

The best thing to do is return the carb to stock specs...rods and jets. The rods can make as big a difference as the jets. Even to the point that you can have a .95 jet with a bigger rod run leaner than a .92 jet with a smaller rod.

You mentioned the carb is used. Even from the factory, the float levels are usually way off. Imagine after some random ebayer's had his hands on it for a while. You really don't even know if the carb's got obstructed passage ways, different power springs, etc in it.

Backfiring is an indication of incorrect timing.

Just randomly tossing smaller jets w/o changing the rods will not get you where you want to be. Also, not knowing what your float level is, what power springs you're running, what timing you have, etc, is not a good way to start.

I'm assuming the motor is stock, since you haven't said otherwise. Set everything to factory specs (GM for the timing and Edelbrock's for the carb) and start over. If it still puffs smoke and runs poorly, then you have other problems.

 

The motor is stock from a 88 chevy truck. I bought the edelbrock intake and edelbrock carb from two ebayers. I checked the float when I first got it as the carb would not work, the mech. pump would not work and come to find out the floats were not adjusted properly. I changed the jets to .92 and seems to run better but not really the way it should. I know what I should really do and that is take it to a performance shop and have them look at it, but I don't know of one to use or trust at this point.

 

Before you take it to a shop, download the instruction manual from Edelbrock's site and read it. It's not very long and it goes into how their carbs work. Once you've read that, go through the tuning section.

The rods are just as important as the proper jet size. You can be way, way off if the rods are not correct. I can already tell you, if you changed jets w/o changing the rods, you're probably off the scale, assuming the previous guy did it according to Edelbrock's recommendation and changed the jet and rods.

Find out what you have in there and use the chart in the manual to see where you're at. The best starting place, cept at high altitude like where I am, is at the center of the chart. Go from there, but first, you need a good, known starting point.

Or, you can bring it to a mechanic who's going to charge you by the hour to do what I just suggested.

C