I am starting a rebuild of a th400. I have the parts to convert it to switch pitch, converter, pump, shaft and soleniods. The thing I am having trouble with is finding out where the plug goes. I have read about the fuse end with the hole but I dont know where to put it. Does it go somewhere in the case?
Yes the plug is on the side of the case and inside the transmission, it consists of two pins one for second gear downshift and one for pitch.
I am familiar with the plug on the side. This is a small plug somewhere restricting oil flow, that you have to put in when you put V/P in a nonV/P trans. Maybe I am mistaken. Has anybody out there done this swap?
You mean the orifice plug. Contact Jim Burek at PAE and he will tell you where it goes. Visit www.buickperformance.com/vendors.htm for his contact info. He is on this board too but I forgot his username.
Have done this conversion many times. The orifice plug goes into a hole under the front pump in the case of the trans. It is located on the bottom passenger side of the case. There should have been some instructions with the conversion kit to show you the location of the hole in the case. As you go up the passenger side of the case from the bottom, there are 2 threaded holes. The orifice plug goes into the hole between the 2 threaded ones. There is a pic in most chassis manuals in the trans section. Here is where things can get sticky, not all cases were drilled for the orifice plug. Most (not all) 73 and earlier cases were drilled. Some 74 cases were and some not. After that, most were NOT drilled. The question now becomes, what year trans do you have? Hopefully, it has the hole already drilled. If not, it can be drilled, but you need to be VERY accurate. Check and see what you have. Supposedly there are some conversion kits available that no longer require the orifice plug in order to work. Since you got the plug with the kit, is appears you will need it or the SP won't function. Good Luck, Mark
Larry, Yes it does, only it is not labeled as it was not used after 67. My 67 manual listed it as the correct hole for the SP. Mark
Going clockwise from the "modulator" hole there are 3 holes. The first one is a threaded bolt hole and the next one is the SP hole. It almost looks like it is not there as the pic appears to have the orifice plug in the hole. The 3rd hole is another threaded bolt hole. What happens on most 74 on up cases is that there is no hole drilled between the threaded bolt holes. I have drilled this hole open into the case passages, but it needs to be drilled smaller first and then a bit larger to fit the orifice plug It has to be drilled complete into the passage and cleaned to make sure there are no burrs or pieces. Much easier to use a pre-drilled case, though sometimes you have no choice on a trans that is already rebuilt. It is also a good idea to "stake" the orifice plug in place so it can't move. One other thing that has not been mentioned is changing the input shaft in the forward clutch drum. That must be done as well as there is a sealing ring on the SP shaft that is not there on the fixed pitch shaft. A press is preferred, but I have managed to swap them without a press. The splines have to be lined up to install it and NEVER beat the end of the shaft with a hammer directly. This could flatten it and then it won't fit into the converter properly. Mark
The picture is perfect. I now know where to put it. Now my next question: Is the plug solid or does it have a small hole? Where do I get the plug? Can I use something else? I thought I heard about a guy who used a fuse end with a hole drilled in it. I did not buy a kit, that is why I don't know what the plug looks like or where it goes. My case is a 70 pontiac so it has the hole already there.
The plug has a small hole in it. It should come with the kit unless you get the one that has a modification to the pump instead. Supposedly, the kit from Jim Burek (PAE) does not need the orifice plug. I am not recommending or critisizing anyones kit here, so please do not misunderstand. A fuse end may work as long as it is drilled the correct size. I have a kit somewhere, but can't recall the drill size. Want to say .020, but don't hold me too it. Just get whatever kit you feel is best and follow the instructions completely. Mark
OK, got an answer for you. Came from George Nenadovich's site. In the article he wrote about the switch pitch. Here's the relevant part: "When changing over a non-s/p to s/p, you must transfer oriface plug behind the pump or the system will not work. If you can't remove the old plug, you can make a new one from the end of the old style glass fuses. Break the glass, clean out the end with a soldering iron to remove the old fuse solder then drill a 0.028" hole in the center of the cap. This hole size is critical. You can also buy a new plug from GM, part 8611710, for $10.50." Here's the whole article: http://www.buickperformance.com/switchpitch.htm
Alright Larry! That is what I am talking about. I read the article some time ago but forgot where it was. I remembered the fuse part but forgot what size hole to drill. I may order one from G.M. now that I have the part number. Scott Muncill
