Contour Enthusiasts Group Archives Forums Modifications 3.0L Duratec 4.6 Mustang TB for the Contour....70mm from MAC

Ok, I put this biitch on Saturday. I made an all day job of it. First off, the MAC 70mm will bolt up, but it does not seal off the whole intake passage. The TB is actually a very compact housing and therefore the top of the intake manifold mouth where the EGR passage is is slightly exposed. To combat this I bought some aluminum sheet and made an adapter plate to go between the provided gasket and the factory gasket. Then the linkage lever was 180 degrees out even when I mounted the TB upside down. Therefore I used a dremel and cut the svt lever off and the one from the MAC off and swapped them. I tack-welded the linkage from the svt onto the mac. The SVT spring wouldn't fit because the shaft was maybe a half inch shorter than the svt TB. I just kinda bent the cable bracket over to the left to match them up.
Next problem. The aluminum stop (that limits the maximum opening of the blade) for the MAC linkage would actually stop the SVT linkage way to soon. So I cut that off.
Then it opened too far with the pedal, So I mounted a piece of metal to the top right bolt that created a stop for the svt linkage.
Fortunately, the 'close' throttle stop actually works fine.
Ok, now I have it mounted up, cables on and working smoothly, and the throttle stops are good.
I fired it up and it wouldn't idle below 2500 rpm!

So I checked the gasket area first, and had use rtv silicon betweent the gaskets. That helped alot, now it was idling at about 1800. Next I plugged the little hole in the TB with some JB qwik epoxy, and that brought the idle down to around 1200. I could completely disconnect the IAC tube and check that it had no vacuum on it which indicated it was completely shut off, and it was still sucking air somehow.
After all that, with the computer completely closing the iac, the thing will idle about 1200 rpm.
I took a cup of water while it was running and I found that when I poured it around the throttle shaft on the linkage side it would make a gurgling noise.
Apparently it is sucking air around the edges of the throttle shaft. So I took some grease and packed it around the shaft and that reduced the idle to about 900 rpm when the IAC is closed.

So that is where I am at. What is a good way to seal off the ends of the shaft?
I have thought about rtv, but when the shaft rotates I would guess that it won't seal anyway, and would make a mess.
I think high-vacuum grease used on various vacuum pump systems would work, but I don't have any at the moment and I don't want to keep replacing it.
I have a feeling that the problem might be that the air is going through the bearing, but I didn't look at it that close when I had the shaft linkage off.

AS far as how it feels. It seems to be much more responsive now, and pretty quick up top. I think I may have lost some low rpm torque, but I can't tell. My original calculations told me that 67mm was a big enough increase, but that is only a qualitative guess.

Any thoughts/solutions are welcome.

warmonger

I'm having a similiar problem . Car won't idle below 1,250 and doesn't derev, but it sure runs like a bat outta hell! I think I need a new throttle plate. Anyone have one? If an extra is available please let me know, and I'll send the cash. Good luck Warmonger, I know I'll need it.

Good luck to you too!

I took the throttle body off until I can decide what to do about the excess air leaking in throught the shaft bearings. Now I can compare, and the 70mm is definitely more responsive and the car is a tad quicker up top. The 65mm may be just as good. I am going to consider it as well before I put this 70mm back on. It just looks too damn big!
I have learned one thing though, I definitely need to uncork the air intake on this car.

warmonger

Wow, sucking air past the shaft bearings??? Is this a totally worn out TB or a result of your tack welding the linkage on? If it's sucking air past the shaft/inner race, you should be able to seal it off. If the seals are worn out on the sides of the bearing, you're pretty much SOL unless you have new bearings you can press in place.

Sorry to hear you guys are having so many problems. Perhaps we should make a list of brands that you guys are using to try to keep others from having the same problems. My BBK works just fine using the "how to" from Demon's post in the performance forum archives.

wavrdr, did you make sure the throttle plate is properly positioned and that the plate makes a good seal in the TB bore? Sounds as if an adjustment is all that's needed on yours...

Brad, I attempted to readjust the plate, but still got the same result. It's definitley leaking(slightly)from somewhere, and it sure is pissing me off, cause the car just opens up with it on there. I may try and play around with it sooner or later, but gotta lot of stuff going on right now-selling house, and purchasing a new one . If anyone comes across a throttle plate for a 65mm please let me know, even for comparison, I'll gladly pay for shipping. By the way my throttle body is off an Explorer.

Well, I think I may have an idea why the throttle is hanging like crazy, a possible bad TPS? Yesterday I reinstalled the stock SVT tb, reset the computer, and let the car idle for a few...then took her for a drive, throttle hang! Not on every shift, but it sure does do it, also throttle voltage on my Apexi' is reading 0.005-0.015, even at WOT! So I think that the throttle hang may be caused by the "possible" bad tps, but now I have to tinker with the 65mm throttle plate, to get the idle in check. Thanks for the advice/thoughts you guys, and keep em' runnin strong. Alan

Sorry to say it Brad, but this F'ing Tbody is brand new, that is obvious. I wouldn't recommend it to anyone unless it is cheap. It isn't a result of the tack welding, besides, I only tack welded the fulcrum to the end of the shaft....you poopoo head!
Of course I'm not that bad!

It is because the bearings the dick_head designers use have no seals on them. They aren't even sealed bearings! It should be easy to seal up, but it still annoys me. I am thinking of machining two teflon bushings to slide over the shafts and butt up against the bearings. I have a sheet of teflon so I know it is low friction, and easy to machine as well. I can make it a press-fit so that it is tight to the housing so that there is very little leakage.

Unless you have a better idea. I am considering scrapping it and getting a mustang TB in place of it. I'm just undecided.
It still sucks though.

warmonger

With the stock TB, sounds kind of like a bad TPS if those readings are accurate.

warmonger

Wavrdr: Your problem is the TPS. I had this exact same problem (a customer did also) when I did the SVT t-body upgrade. Check the wiring connection on the TPS plug or you could have a bad TPS sensor. Swap over your old TPS-they're the same.

Tom: I'm now converting 65mm to proper SVT spec./operation. E mail if you're interested. I order new 65er's, but I'll do a used 1 if you send it to me.

Still looking for 3.0 lower IM throttle plates! Who's gone secondary-less?

Well, I got my 70mm to work.

In addition to the adapter plate I had to make earlier, I decided to make the linkage identical to the SVT so that I would have the same pedal feel.
The problem with that was the shaft was almost 1/2" too short. I bought a steel dowel pin that was 3/8" in daimeter (shaft was 10mm diameter) and notched it to fit onto the end. When it fit almost perfect, I welded them together and ground off the welds. Then I cut to the right length and made a slot to fit into the svt fulcrum. Then I sealed the shaft on both sides with o-rings and grease. Last, I put the svt springs on and put and then tack-welded the svt fulcrum on.

Installed it into the car and it worked fine. The idle is where it should be, and the pedal feel is identical now. It even takes off about the same, but there is more go-fast power above 5K rpm!
All in all, a worthwhile mod to the 3L project.
With the eManage tuned so that I can run a stock SVT MAF with the centerpost cut out (very low restricion/large area) and the 70mm TB, I have a very low restriction intake.

warmonger