Hey guys, 2 questions on my conversion: 1. The 455 is in and running great, BUT, the center of the intake manifold on the driver side (between 2 and 4 cylinders) get up to 300 degrees in no time at all and the front and rear are at 150 degrees. Is something wrong or is that the way it is? 2. The floor shifter conversion will give me, park OR 1st low, but not both no matter what adjustments I make. Very confused.
The center of the intake manifold has hot exhaust running through the crossover passage. The crossover can be blocked at the cylinder head but the choke won't be warmed sufficiently to come off. The engine will be extra cold blooded in winter temperatures as well. The cooler intake makes for better performance. There are pluses and minuses to doing it. BTW, the driver's side is cylinders 3 and 5. You may have the wrong cable, or bracket. The bracket that bolts to the pan is different between 350 and 400.
Yes 3 and 5. sorry, what would block that passage way? wrong valley pan? And i thought the cable was too long in the first place, but that's what came up in the search for it and I figured if the travel from the shifter is the same distance it shouldn't matter.
No, you don't understand. There is an exhaust crossover on all stock intakes, and some aluminum intakes. The crossover passage is there to warm the under side of the plenum to help with fuel vaporization. In the center of each head is passageways that let hot exhaust gases into that crossover. The stock valley pan has an opening for that. What some guys do is use freeze plugs to block the passageways in the head on each side. The heat from the hot exhaust is NORMAL. That's why the center of the intake gets hot. It frequently eventually burns the paint in that area. The bracket that holds the shifter cable, the one that uses two pan bolts to secure it, that bracket is DIFFERENT for the THM350, and the THM400. If you have the wrong one on there, that could be your problem. The bracket on the left in this picture, https://mrbuick.com/wpimages/wpf8323e7d_05_06.jpg
Ok, I got what your saying, and the pic you attached does show a different shape piece that turns the shift shaft than the one I have. Thanks for the Info Larry. Appreciate It.
Those pieces are available from ToddsGS here on V8. His site is Stage1restoration.com https://www.stage1restoration.com/product/floor-shift-cable-bracket-th400/ https://www.stage1restoration.com/product-category/transmission_automatic/page/3/ And Mrbuick.com, https://www.mrbuick.com/reproductionparts.html
There's nothing wrong with the heat if you run your car in below 40* weather regularily. Probably not a problem in Florida. However if you want a few extra HP from a cooler intake block off all four passages next time you pull the intake. If you have a choke pulloff in the stock intake just drill a single 1/4" hole in the plug closest to the pulloff. That is all you need to heat the intake and make the choke work except in the very coldest conditions. Then I would say put a 1/2" hole in it.
