dinoteam

I've recently decided I'm going to replace the stock 4bbl with an Edelbrock 1406 -- but I'm having a hard time determining where the hoses are connected at the base. The stock carb had a total of five outlets, and this carb has just three -- I don't want to make a mistake and damage anything (if I don't have to).

Does anyone have a how-to or some tips for installation? Working with an 86 Trans-Am, AT.

acescarrsRS

Here's a pic of what all the outlets are on the Edelbrock carb. Not sure what purpose all the original vacuum hoses are though.

Damon

If you could post a picture of the original (QJet) under-hood emissions tag (that has the vacuum hose routing diagram) I could match things up for you.

acescarrsRS

Not sure if this is the pic you're talking about. But this is off my 83Z28. Not sure of the differences each year.

devestator_x

iTrader: (1)

I just recently installed a 1406, at least I think it was 1406... 600 cfm, electric choke. Anyway, it looked the same in front. The middle is for your postive crankcase vent (PCV) it should connect to a larger 3/8" hose coming from your drivers side valve cover (at least mine did) The left port (timed vacuum advance) will need to be hooked to a vacuum advanced distributer. I dont believe you have one yet as you had the stock carb on there and I think that it is computer controlled. I may be wrong and you may want to read up further on the Qjet carb and your distributer, but I know that the carb you bought is not computer controlled. The right port can be used for other vacuum driven accesories (vents and what not) Someone correct me if Im wrong here. I know I need to purchase a vac advance dist for my 82 LU5 which had crossfire FI, right now its in limp mode.

When you counted the five ports on your stock carb, did you count Power brakes and fuel? If you did then this carb also has 5 the fuel is on the left side near the top, another 3/8" fitting up there. The power brakes hook to the threaded hole in the rear of the carb at the bottom. you will need a threaded adapter to hook the hose to this ($3.50 or so at the parts store) Hopw this helped somewhat not confused you further.

Damon

I'll double check this later today when I get home but I beleive these are the functions of the various ports on that QJet tag. I'm matching the letter of the vacuum port on the Qjet to the function of the port on the Eddy:

J- timed vacuum
B- full manifold vacuum
L- PCV hose
T- full manifold vacuum
H- timed vacuum
N- full manifold vacuum

Power brake booster can be connected to either the big 3/8" vacuum fitting on the top of the intake manifold behind the carb (if manifold is so equipped) or to the big 3/8" port on the back of your new Eddy carb- your choice. Plug whichever you don't use.

Please note that the "timed manifold vacuum" port on the Eddy isn't EXACTLY the same type of timed port on the QJet. On the Eddy the vacuum goes from nothing to full vacuum very quickly around 5% throttle. On the Qjet it "ramps up" more gradually from about 5% to 10% throttle. Similar, but not truly identical. I think it should still run OK, though.

When you're done, double check EVERYTHING again against that emissions tag that was posted above. It is EASY to get this stuff screwed up- lots of hoses, lots of Ts, lots of connection points.

Damon

I got one of them wrong.

T = carb bowl vent (no equivalent port on the Edlebrock)

You can leave that line just laying disconnected- it's just part of the evaporative emissions system- leving it disconnected won't affect how the engine runs.

PhantomFE3

looking at that diagram, what would happen if you got a new intake manifold and there wasnt a provision for the 'purge tvs' that is connected to the cannister and the cannister control valve?

Apeiron

A TVS is a Thermal Vacuum Solenoid, it's a vacuum valve that opens when the temperature reaches a certain point.

If the new manifold doesn't have a port to mount it in, you could remove it and the rest of the vapour control system.

Damon

Yeah, you wouldn't want to go without that. If you ran without it but hooked up that vacuum line directly the evaporative emissions would be purging any time the engine is running- which would make the cold engine drivability rather bad. Or you could leave it disconnected and it would never purge, in which case you might as well take all the evaporative emissions stuff off.

dinoteam

Just a quick note of thanks... all fixed up now!

WaaX

ive needed help from someone who actually knows the the routing of the vacuum lines. This is a great help to me, I bought the car and after so realised that the vacuum lines were rigged up pretty badly. im missing the canister control valve and the charcoal canister isnt hooked up properly.

http://img131.echo.cx/img131/7008/74hr.jpg

thats a picture of my engine currently..

is the part thats sticking out in the picture that has the blue paint on it the "purge tvs"

is there anything i can do to this thing to get it running better?

Damon

Yes, that's the purge TVS.

You're missing a LOT of stuff under there from the evaporative emissions system. Fortunately, you really only need it for emissions- it won't affect the running of the engine in any way if it is all removed (like yours has been).

There are really only a few CRITICAL vacuum connections that must be hooked up properly for the engine to run right:

1. EGR system. Look at the diagram and make sure yours is hooked up just like that.

2. Vacuum sensor (rear most vacuum port on the carb). That's gotta be right, too.

3. PCV valve (yours is fine as-is)

Obviously, you need the power brake booster line hooked up if you want power brakes, and you need the vacuum line going to the vacuum reservoir (round black thing) hooked up properly if you expect to be able to adjust where the air comes out of the vents inside the car when you move the HVAC controls. Also, you don't want any vacuum leaks from unused vacuum ports or anywhere else on the intake. But pretty much everything else is trivia beyond that.

Once you get this stuff hooked up right then you can determine if anything else might be the cause of a poor-running engine. Just get the vacuum lines hooked up right before you start throwing any more time or parts at the engine.

WaaX

Thank you I apprecaite your response, after I bought the car I realised it didnt have an EGR system, the guy put a plate where it connects to the manifold and blocked it off.

Apparently the people who owned the car before me could give a crap less about the environment, the car doesnt even have a cat.

thankfully? I live in michigan where the emissions testing was done away with. otherwise I sure as hell wouldnt be driving this car.

Would the purge tvs be causing a vacuum leak? can I get some sort of insert to block it off on the manifold?

Apeiron

You can put a normal pipe plug in the manifold instead of the TVS.

Damon

The TVS itself won't cause a vacuum leak. It's screwed into the water jacket.