Another question for owners of street driven Tunnel Wedge intake manifolds !!

[427LX]

I have to come here to try and get good info on the characteristics of the tunnel wedge intake design. I have my custom made intake of same design but made to fit
the 9.5 deck Windsor engines of 351 thru 440 cube stroker versions...mine being 427.

Now what I have going on is the intake is very cold natured on startup even on an 85 degree day.  With the idle and cruise A/F at 13.4 to 14 at normal 180 F temp it runs fine with great response running off front carb in a progressive linkage setup on a pair of Holley 770 CFM carbs with vac. secondary.

On first startup I have to keep RPM in the 1800- 2000 range to keep it running at a 14.9 range...higher RPM the richer it is. Anything below 1500 and it sputters at 16 A/F ratio. As it comes up to temp it will settle down at it's 1000 rpm idle at a 13.4 A/F. Drive  it and then after a 20 minute shutdown with engine still warm  you still have to keep the RPM up to 1500 for a decent fast idle and then it will settle down to it's normal running. No chokes on the carbs. I tried a manual Holley made  choke and it did do the job but the pivoting cable lock and flex from even a solid cable did not let the choke blade fully open...too much slop.

Now on a cold startup I plug in my engine coolant heater which I used on my other intake during chilly temps to heat the intake and that helps. Other than this it pulls like crazy above 4000 RPM!
Note....carb jetting is now 76 Primary and 84 in Secondary both carbs.  Stock .075 IAB and stock R-3310 idle fuel jet. Idle screws  1 turn out all around.

Do you guys that run the FE 427 Tunnel Wedge intake on the street have same issues or is mine a strange case? Thanks for any help!

[1964Fastback]

Others with actual tunnel wedge experience will hopefully chime in but I think getting a choke working would be the simplest and best solution.  I haven't used the Holley kit so I'm not sure why it won't open fully.  On my 3x2 setup, I used the cheap Dorman "Help" manual choke kit and it works fine for me.  My only "trick" if you want to call it that, for achieving full choke open was to adjust the cable so that the knob under the dash is not fully seated against the bracket when pushed all the way in (open position).  There's maybe 1/16" of gap there.  I was afraid if I adjusted it so that the knob was all the way in when the choke was open, it might end up leaving the choke a little closed.

Pat

[427LX]

I have an idea to mount a small 12V servo motor to connect to the choke shaft. You could work it at a variable rate with a control like a volume control. Have plenty of area to mount it to on base plate.

[Stangman]

I don’t know sounds like a vacuum leak.

[Jb427]

My bbm tunnelwedge on my 482ci engine takes 3 good peddle pumps and it will fire right up I need to keep mine at 1000 to 1500 rpms till my temp gauge starts to move then it will idle Mine idles at 800 rpm mine will also not want to idle after sitting for 20min hot but not for long. I think this is just part of having a spicy engine not sure what specs your engine is but mine is just over 11 to 1 comp larger cam cnc heads 715 vac sec carbs progressive linkage My car is c6 auto 3500 stall 3.5 rear gear I have great driveablity and it has instant power.

Use an electric choke sounds like your in a cold place if you are using a engine coolant heater. You could also try a hotter plug I run a ngk 6 but you could try a 5.

[Drew Pojedinec]

You can use the fast idle parts from a manual choke without choke plate if desired.

You can also richen carbs if needed, tho that may throw you off elsewhere. 
Make sure your pcv isn’t allowing in a large mass of air.

[Jb427]

I don't use a pvc valve my carbs also don't have any vacuum ports only ports for the balance tube for the vacuum secondary's I use a port at the manifold a vacuum line that goes to vacuum tank comp cams type then to my remote brake booster and one that goes to a second factory vacuum tank for my A/C controls. I have no choke on my carbs

I Don't find mine that big of a problem it can be annoying with a warm start when your in a tight car park and it dose not want to idle if I keep mine at 1k rpms for a few seconds it comes good
I am not sure what jets I have idle mixture screws got adjusted on first start 4 years ago and I have never touched them since then my carbs got custom made to my engine specs and have been great looking at my plugs they are on the rich side but not by much

[My427stang]

So, if you start the car and have to put your foot in it a little to keep it running, you likely have the throttles open enough to start pulling fuel through a booster.

What sticks me is that it is so lean (14.9) and if richer, it's fighting you more, it should be less

I rethought this response a few times and still not comfortable, but if that's the case, and the idle/transition are not letting it do it's thing cold, maybe low float level or large HSAB keeping the booster from flowing fuel with the throttles cracked?

My Ford TW had repop carbs on it and the air bleeds were all over the place, but now, cold it fires, I feather it for 2-3 minutes in a 73 degree shop and it chugs away happy after that.

[Jb427]

Mine is the same Ross 2/3 min of feathering and its good to go

[6667fan]

I would put an electric choke on the front carb. Let it warm up that way. Set the kickdowns for 1600-1800 for high and 1200 for low. Don’t even look at the A/F until you have some heat in motor/ exhaust. Idling cold with a big cam will give confusing numbers. ( and a cam with a lot of overlap combined with a low idle can give skewed numbers even when warm)

Drive at least two miles before you get to tuning/worrying about cruise A/F.

[pbf777]

Don’t even look at the A/F until you have some heat in motor/ exhaust. Idling cold with a big cam will give confusing numbers. ( and a cam with a lot of overlap combined with a low idle can give skewed numbers even when warm)

     +1 

     But actually at anything less than the engine speed (R.P.M.'s & throttle angle/load) that provide for at least some form of reasonable directional stability, in both the induction and the exhaust pumping, one will be provided with questionable numbers from O2 sensors.   

     Obviously a major problem with this style of intake is going to be fuel control, particularly distribution at low engine revolutions, compounded when the induction doesn't present an adequate sum of heat to aid in the vaporization of the fuel; and the staged carburetor opening just makes for even greater challenges under these conditions.   

     Though I do understand the intention of "streetability", and yeah I am aware of how Ford Motor Co. dun it, but particularly with bigger camshafts, in all honesty both carburetors really need to mimic/mirror one another, which one will find will better the situation.   

     Scott.

[TurboChris]

On my 66 Fairlane,

482 / Ebrock heads / TW / Holley 600's no choke / TKX / 500 hp.

1 pump and hold it to the floor and it fires instantly. It will idle at about 500 / die for the first 10 - 20 seconds so I feather it at 1000-1200 rpm. Then it's enough to back it out of the garage and down the driveway (idling at about 700) and start driving carefully down the street. But usually I just feather it until the temp starts coming up. 2-3 mins aand just go. I don't get my normal 900 rpm idle until it's pretty much up to temp. (180)

Today I fired it up and immediately starting driving after sitting for 3 hours. No muss no fuss.