Separate Plenum

Last major thing I want to do before I finish putting the engine back together is to take the plenum apart. There is a ton of carbon build up that I want to clean out, and I can't be sure if I have cleaned it all out, especially on the butterflies. My throttle body had enough build up on it that it was causing the throttle to stick. I can only imagine how bad the plenum is.

I haven't seen a thread on it, or haven't seen it in a service manual. Is there any reason it would be a bad idea to do it?

I've taken them apart to polish them... just make sure to clean all the old sealant off and reapply new sealant. If you take off the VIC motor, read the manual on how to put it back on. Since I haven't put one together in almost two years, I don't remember the procedure.

Okay. Just wanted to make sure there wasn't a special gasket or anything. I'll have to find the procedure for the motor. I don't recall seeing it in the manuals I have, but might have missed it. I already popped it off once to get a look inside to see if the butterflies could slide out or not. Thanks for the heads up.

Just mark the plastic runner things inside (the top half of the plenum), which way they slide in... make life a little easier (they should just slide out).

And I used high temp grey sealant when I put them back together.

Got around to trying to separate them, and they're on there pretty good. Probably isn't helping that it's 30 degrees in the garage. Are there any alignment pins to worry about? I'm going to stick it in an oven and see if getting a little heat in the aluminum will make it a bit easier to separate, and then hit it with a wood block and hammer.

I always just hit it w/ a plastic or rubber mallet. Doesn't leave any damage and gets the job done.

I got around to splitting it apart today. I took my propane torch and warmed the split up. I put a 4x4 on the floor and hit the plenum on it to knock the big piece loose. Then heated the next split, and used a nylon-headed hammer to tap the two smaller halves apart. It took a bit of tapping, but it came apart slowly but surely. So here are some pics to show you why I hate trusting someone else to do work on my stuff.

http://i988.photobucket.com/albums/a...T/DSCF0918.jpg

http://i988.photobucket.com/albums/a...T/DSCF0920.jpg

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The blaster didn't think anything of blasting through the masking I put on it more for keeping dust in the garage out than actually protecting it from bead blasting. Should be in the 50s tues or wed, so I'll use the parts cleaner to wash it all out then.

Just have to get some high temp sealant and it can be slapped back together. Put it through the parts washer and scrubbed away. Glass is all out and a chunk of the carbon residue. Finished with a little bit of scotch brite and air blasting any little bits of grit out from the butterflies.

http://i988.photobucket.com/albums/a...T/DSCF0924.jpg

http://i988.photobucket.com/albums/a...T/DSCF0925.jpg

Got my calipers back, so the last thing left is the Addco rear sway bar, which is another two weeks out.

Looks good! Glad you took the time to do it right.

The butterflies should be closed when you put it all back together. When you put the vics motor back on you have to angle the motor towards the hood then when the teeth meet the gear inside the motor you twist it until the butterflies are closed and the bolt holes on the motor meet the ones on the manifold. Great job on cleaning that carbon. How many miles are on your engine?? yours look pretty bad compared to mine when I had it apart at 200k miles.

Thanks for the complements. It has been a long time coming getting this back on the road. Halfway through getting the rebuild calipers back on, then back to putting this together.

I have a variable power supply that I was planning on using to check that I have them positioned right, but haven't got beyond that thought. But your way is a bit easier.

I only have 175k miles on it. I bought it around 100k with a snapped timing belt. The previous owner probably never did the timing belt change. Had the heads rebuilt and did all the other 120k stuff to get it running. Timing belt tensioner failed at 10-15k, but I caught it before the belt jumped and it got off timing. But yeah, there was a lot of carbon build up in the throttle body and in the lower plenum, mostly on one side of the V. Tranny lost reverse and 5th, but since I had so little money in the car, I decided to just tear into it and fix and replace everything that needed it. Hopefully the work pays off.

Now only if that Addco rear sway bar would get in...

That sounds exactly what i had to do to my car when I got it. Ive got an addco im ge. You getting rid of. you should have done the front TT brakes upgrade.

The problem with the brake upgrade is I would have had to replace my Mille Miglia wheels, and I really like my wheels.

I'm happy with the stock brake performance. They match my needs. I have other vehicles available if I want more performance.

Even on first gen TT brakes they wouldn't fit? Im on 17 inch mustang rims and they fit pretty nicely

The wheels are 16". I'd rather spend the time and money on other things. I don't need this to be the fastest thing on the road. Again, other toys for that.

Got the plenum back together last night, and have a few more tips to put in for anyone else who does this.

The VIC motor works on current flow. Apply voltage (3-4V @0.5mA was enough) in one direction, and the motor spins one way. Switch the wires around, and it goes the opposite. When you take the motor off the car, it should be at the position where it has the butterflies blocking off the short intake. You can apply the voltage to make sure it is in the right spot before bolting it down. You apply voltage to the plug with two pins in it.

When putting the butterfly section and the throttle body section together, it is much easier to get them to fall together if you place the black plastic pieces on the throttle body part, and lower the butterfly section on top of it. It also helps to have a nice flat surface to make sure the section where the throttle body mates to is as flat as possible.

Final comment on this. You will need to get the throttle body part recut. I used a 1-2-3 block to get it flat. It was about 0.006" off, and that was enough to cause a leak.