Edelbrock 1406 vacuum lines

[Bryon]

A PO put a 1406 and intake on the AMC 360 on my 89 GW. They also replaced the original distributor with an HEI and got rid of the air pump/cat.
I just rebuilt the carb with some adult supervision and am still having to drop a splash of fuel down the carb to get it started. The stumble that I was experiencing is mostly gone once warm, but there is no easy accelerate.
The friend that helped me rebuild the carb tells me there is a vacuum problem. He thinks there is maybe too much negative pressure? The can on the Driver side fender crimps in slightly when I rev the engine.

The line from the brake booster goes to the large middle nipple on the carb.

The little one on the left goes to the HEI, and the little on the right goes to a valve just behind the AC compressor and the line from the charcoal can to the carb also connects to that valve. These 2 small lines were reversed when I got the Jeep, but I switched them because of the red marks and it seemed to run better after I did.




First FSJ. 1989 GW, AMC360 W/ HEI AND Edelbrock single 4bbl. Was told the engine was rebuilt... starting to question that after the horrible wiring I found.

[letank]

it is a bit off according to edelbrock instruction sheet

the brake booster port is in the back, the front large port is for the PCV valve

the right small port is a manifold vacuum port, so you can cap it or send it to your vacuum reservoir tank is no cap avail.

the left small one is correct for the ported vacuum to the distributor

according to edelbrock, you can get a pdf version for the installation instructions
https://www.edelbrock.com/performer-600 ... 40546.html

[Bryon]

Thank you for the info and link!


First FSJ. 1989 GW, AMC360 W/ HEI AND Edelbrock single 4bbl. Was told the engine was rebuilt... starting to question that after the horrible wiring I found.

[PossumJr]

The big port on the front and rear are both manifold vacuum, it makes no difference which your PCV and brake booster are connected to but since the pcv is on the rear of the intake that is where it normally ends up connected on a AMC V8, on something like a SBC (far more common application of an Edelbrock carb) it's normally hooked up as stated in the manual. Here's the 89 vacuum diagram:

I recommend starting with the basics. Do you know where your timing is set? Have you checked for any sources of vacuum leaks and what is your vacuum at idle? There originally was a mess of spaghetti of vacuum lines on that engine due to emissions and you could have something hooked up incorrectly or not hooked up at all (refer to above picture). Is the accelerator pump functioning correctly? Also what, if any, emissions related equipment is still installed?

[Stuka]

The front and rear ports on the 1406 are the same, just a different diameter. Since our PCV valve is on the back on the intake, many route the PCV to the rear of the carb.

But your setup seems fine as far as vacuum goes, provided you don't have any vacuum leaks.

For the starting issue, is this only when cold when it has been sitting for a while? If thats the case, the fuel bowls may be leaking so that they are empty when it sits. This is not uncommon. I would install a clear fuel filter so you can see when fuel gets pumped up to the engine. If there is fuel getting pumped up and it still won't start, then there is an issue with the carb, such as the accelerator pump not working perhaps.

[sansabarJ]

Hello ,

On the 1406 there , the small vacuum hose that goes to those red paint marks does nothing at all . you have essentially a manifold vacuum port hooking to a carb manifold vacuum port .( same vacuum )You can leave that or put vacuum plugs , SO that is ok .Stuka is correct on the front and the rear PCV / BOOSTER HOSE location , makes no difference .Using the stock emission diagram helps only to confirm a couple of your vacuum connections .It is clear you do not have emissions and the diagram is irrelevant for the most part .A 1406 Edelbrock is available in many configurations ( see the listings ).One issue that Edelbrock did was make the upper pass side vacuum port full vacuum and also ported vacuum )meaning : The upper port on pass side front of carb "CAN " be full vacuum at idle as well as no vacuum at idle .
The ported source can be hooked up to your distributor advance directly if your EGR is now deleted . Set your base timing to about 10 or 12 degrees initial . vacuum hose disconnected from your dist while you set your timing . If your ported source is FULL vacuum ,this will speed the engine way high , requiring you to reset your idle speed .If it stays at idle upon reconnecting your vacuum hose to your vacuum advance on your distributor , your set to go . check the vacuum there so you know what you've got . Its pretty straight forward .I am wondering about the vacuum can sucking itself inward though , I do not know what can you have , sounds like your vacuum reservoir . As far as your carb leaking of fuel while sitting ,it can be possible . I will suggest to remove your air cleaner , and with engine "OFF AND NOT RUNNING" look down into your front carb bores and work your throttle linkage and you should see a STRONG stream of fuel squirting in thru 2 little nozzles . If you do not see this " engine cold" or hot you may likey have the following : first , too low of fuel level ( float settings are too low ) or second , your accelerator pump passage has a blockage or the check ball or small weight that goes into the accelerator pump passage was not reinstalled . A partial squirt of fuel is a indication this is possible .
Check all the details of your carb work .

sansabarJ

[sansabarJ]

I wanted to add to the install of a clear fuel filter , a good idea , put it "before" your metal stock filter if possible ( away from engine heat ) Do not delete the stock return 3 port filter .It serves to return fuel back to your fuel tank and keeps it cooler by recirculating the fuel .It also bleeds off high fuel pressure back to your fuel tank . Stock pumps put out 6 to 7 psi of fuel pressure so this is a proper filter to retain .


sansabarJ

[Fast79Chief]

Bryon, what do you know about your engines vacuum at idle? How many hg of vacuum is it pulling? If it's anything like my 79 360, it has a ton of vacuum at idle. The Edelbrock carbs need to be set for the idle circuit according to individual engine idle vacuum. I had to use their strongest (SILVER) springs for the idle circuit drop down rods. Position you accelerator pump rod in the highest position (closest to the air cleaner). Passenger side vacuum port goes to distributor.
Use large vacuum port at back of carb for brakes.
Large port in front for pcv.
Get an owners manual for the 1406, and study it thoroughly. The springs and rods you use for the idle circuit make a HUGE difference in the way these carbs respond and run. Get a good vacuum gauge and learn to tune your carb by vacuum signal.

[Bryon]

Bryon, what do you know about your engines vacuum at idle? How many hg of vacuum is it pulling? If it's anything like my 79 360, it has a ton of vacuum at idle. The Edelbrock carbs need to be set for the idle circuit according to individual engine idle vacuum. I had to use their strongest (SILVER) springs for the idle circuit drop down rods. Position you accelerator pump rod in the highest position (closest to the air cleaner). Passenger side vacuum port goes to distributor.
Use large vacuum port at back of carb for brakes.
Large port in front for pcv.
Get an owners manual for the 1406, and study it thoroughly. The springs and rods you use for the idle circuit make a HUGE difference in the way these carbs respond and run. Get a good vacuum gauge and learn to tune your carb by vacuum signal.

Thanks Chief!
I do not know how much hg I’m pulling. Is a vacuum meter something I can rent at autozone?

I didn’t change any jets, rods, needles, or springs with the rebuild. Only cleaned, trued the floats, new acc pump, and new gasket.

I have really learned not to trust ANYTHING from the PO(s) because there was a lot of hacking and just plain stupidity.

He claimed to have rebuilt the engine with a cam for towing, which makes it very torqy at low RPMs and that is leading to stumble. I have switched the acc pump lever(on the outside on the throttle) trying to cure the stumble.


First FSJ. 1989 GW, AMC360 W/ HEI AND Edelbrock single 4bbl. Was told the engine was rebuilt... starting to question that after the horrible wiring I found.

[Fast79Chief]

Bryon, you can buy a guage for cheap. It will come with the hose and a few fittings. If you're going to own an Edelbrock, you need to own a vac guage. Now that I know you haven't looked at the idle circuit rods and springs, I know you can get it running better once you READ just what they do, and how to tune by changing them. This is why you need the 1406 Owners Manual. Get one and it will change your life. lol

[will e]

Autozone should. They can be purchased pretty cheap and are a handy diagnostic tool. Here's an example from Amazon, I picked this at random and do not own this specific one.

https://www.amazon.com/Lisle-20300-Vacu ... 93&sr=8-24