I've seen posted that the swap in a '66 Skylark from a 2-sp ST300 to a TH350 is basically bolt-on. My question, however, is what happens when you want to do that with a column shift? Does the TH350 support column shift? What about the detents since the column only has detents for D and L, how do you get all 1-2-D? Any thoughts or comments? Thanks!
D is still drive and L winds up being 2nd. Depending on the rigging, you might be able to pull the column lever down past L and get 1st. I say put her in drive and go.. If you really want the option of shifting manually, a console shift is next on the to do list. I don't shift manually with my column shift. The detents are far too "iffy". I wouldn't want to think of what happens if I were to slam into reverse at cruise.
I replaced a st300 with a t350 a few years ago in a 65 lark with a 300cu.in. There is enough throw in the column shifter to hit all positions on the t350. The detent worked well enough for me to lock out reverse and lock into park. The only noticeable change is that the indicator pin won't land evenly on any letter or number which didn't matter to me since I shift by feel not by sight. And yes, I was able to shift manually through all three forward gears with no problems. Otherwise, it was a direct bolt on swap. My only problem was getting a dipstick tube to fit properly (can't use the st300 on the t350). I used an aftermarket tube and did a little heating and bending. Also, it threw my speedo way off so I had to address that problem. Hope this helps.
The speedo was only off about 5-10 mph. My final drive ratio was 2:78 and the car it came out of was I think around 2:56. I just left it alone being that I rarely check my speed anyway. After 36 years of driving, I can basically feel how fast I'm going, especially at low speeds (hope I didn't jinx myself).
Every transmission have 2 gears in them to calibrate the speedo. On on the output shaft, drive gear, and one in the speedo hsg, driven gear. There is a ratio that is set-up between these 2 to get the speedo correct. Here's the readers digest version. 60 mph on a speedo is 1000 rpm. What you need to do is determine what rpm your engine will be at when doing 60 mph. This is easy to calculate, you need to know the rear-end ratio, tire diameter and apply this simple formula: 60 times axle ratio times 336, then divide this number by the tire diameter in inches, this will give you the rpm at 60 mph for your car. Let's do one . Say you have a 3.08 rear end and a 24 inch tall tire. 60 X 3.08 + 184.8, then x 336=62092, now divide that by 24 and you get 2587. So this car will be at 2587 rpm at 60 mph, we know the speedo needs to see 1000 rpm to be correct. Now you simply come up with the correct ratio of driven gear teeth to drive gear teeth to get as close to 2.587 as possible. An example, I'll use a t-400 here , if we use a 44 tooth driven gear, and a 17 tooth drive gear, 44 divided by 17 gives you 2.588. This is pretty much as perfect as you will get. 2.588 x 1000 gives you 2588 rpm, but the speedo sees 1000 rpm. Now was'nt that easy? :Smarty: Jim Burek
TTT Would a turbo 400 hook-up the same as a turbo 350?My bro went to pull out the trans that he's selling me and he just found out its a th-400,will this still work with my 300 engine?How does it hook-up?
TTT Would a turbo 400 hook-up the same as a turbo 350?My bro went to pull out the trans that he's selling me and he just found out its a th-400,will this still work with my 300 engine?How does it hook-up?undefined As long as the TH400 has a BOP bolt pattern, it will bolt right up including the torque converter. The shift linkage should be OK also. A problem will be if the TH400 is a long shaft, you'll have issues with the driveshaft and possibly have some pan clearance problems with the crossmember. Also, the TH400 uses a larger yolk so the driveshaft will need attention, even if the trans is a short shaft. The speedo hookup is OK and I think trans cooling lines will work. Another issue will be the kickdown switch. I'm not sure if the switch from the st300 will work for the th400 but I suppose it could be modified to work. Best thing to do is to take a lot of measurements and compare them to your trans.
