TOPIC: 1990 Ford Van E-150 5.0

OK Willis, here's my crude photo alteration to your pic to recommend what I'd do. This is IF that square hole we've been yakkin' 'bout is only open at the bottom, OK? Here it is in it's crude form:








I'd dam off those bore notches that let IAC air in each bore, then cut a larger notch at top of the square "box", and a smaller notch over the throttle shaft on sides of the square.

Get a business card or two, wrap 'em in clear 3M type shiny box tape. Cut 'em down so a piece fits in between the closed throttle plate and bore wall, tightly against each of the bore notches. Might need to put something aginst the card pieces in each bore to keep 'em tight against the notches. Wrap a socket w/ tape and fit into the round hole to keep JB out of the hole. Obviously clean this TB up well before you use JB Quick, solvents/carb. cleaner can attack epoxies. Then roughen up all areas where JB is going to be w/ a small drill bit or burr in the Dremel, maybe roughen the bore notches w/ a small fine file gently. Put taped socket into round hole and fit the card dams in place, I'd cut the card's so they extend up above the bore notches, but keep em low enough to get in there w/ your JB. Build up the epoxy dams a bit above the base of the casting so you can sand flush after full curing. You let the JB Quick get mostly set, then pull the cards and socket out.The clear box tape will keep epoxy from sticking. The dams will extend the throttle bores down to base, preserving Groove waveform. The new notches will direct IAC air thru the square opening and thru the new notches directly over throttle shaft, keeping this airflow separate from Groove rolling waveform. I'd make the notch at top of the "box" larger and the new bore notches over throttle shaft smaller. If cold idle RPM is too low after Grooving and re-install, you can open up the bore notches as needed. IAC opens up to give high flow at cold engine startup,fast idle, then gradually closes to reduce idle RPM as engine warms. You need that cold start fast idle RPM in cold weather, esp. if lights, heater and wipers are on. IAC also increases airflow w/ AC turned on.

Need to strike a balance between allowing for proper idle RPM's under different conditions, yet controlling how much air goes in and bypasses throttle plates and the Grooves. Some Gadgetfolks in cold climates have opted to reduce IAC flow, and adjust w/ idle speed screw. Primo ignition tuneup parts also support good idle quality, and need to remember what Ron has told us about Vac. leaks, hunt 'em down and Kill 'em!

Hope this helps!

Tracy G

Modding the IAC this way helps the Groove to work better, and you can reduce overall IAC flow this way too. Idle RPM's for hot engine base idle speed can also be adjusted w/ idle stop screw. Hit it w/ penetrating oil during the clean up.

HI TRACY

some more pics
square opening has no outlet gasket seals it off
should I use a med bit ;to do this groove?
thanks
willis

Ok Willis- head scratch time. That vacuum nipple you say connects into the square opening--I need you to look on your truck and tell if it is in use or capped off, if used try to track down where it goes to if posibble. Also we're gonna need to see the intake man. flange where this TB mounts to, I need to see it. BTW, when you do swap the TB's use a new gasket it's 24 yrs old dont trust it. This is a pretty simple TB gasket shape, you might make your own from bulk gasket material, w/ xacto knife on soft pine board. Dan Merrick says he uses heavy tar paper to make TB gaskets from too. I'd also be suspicious of the rest of the intake man. gaskets and all vac. lines to man. vacuum. Ok I'm gonna do another graphic of Plan B for the IAC mod, this will be a different route.









Sorry my touch w/ this graphics is bad! Fill the bore slots as before, but cut narrow trench slots at top, and a notch in the bores as shown. Using that casting void, we're dumping IAC air almost over throttle shaft ends,this is still far enough from the Grooves to be OK. Go slow w/ those top slots, I don't know what those 2 dinky holes are about either. Prob. going to need a small diameter burr bit for Dremel, like a small drill bit but rough down the sides. You can cut narrow and deep for shape of top slots, but watch out for how this casting is done. Dont want to leave any unduly weak spots. Bore notch where IAC air enters, try to leave room to enlarge 'em later if needed.

For the Grooves- you have to judge by casting thickness where Grooves will go. Back-fill or fill outside w/ JB Quick as needed. Rule is to always use the biggest bit possible. On my first couple of Grooves I practiced on junk extra TB's. I dip my bits in used power steer fluid between cuts to lube & cool 'em. I usually don't go above med. Dremel speed. check your Groove work w/ flashlight in and out!

I'm showing this based on assumption that that center vac. nipple goes to something important, so this avoids using that center "box" casting. This TB is a trip, I need to go to Pick'n Pull, yank one off a Ford and examine the wolly-bugger! IAC re-working can get Interesting on some TB's! Pics of the exposed intake man. TB mounting flange may shed more light on this Ford. Once we figure this one out, that's great, there's still tons of these old Ford's around! Plus they have early "dumb" ECU computer that won't fight gains so much!

Tracy G