So, I woke up this morning craving a 4 speed manual behind my 425 in the t-sedan I'm building. Yesterday I was planning on building it with the th400 (with switch pitch converter). The question is should i follow my idea of the 4 speed or run with the initial plan. And if so how would you guys suggest switching the 425 to a manual ******?
Either way you'll never get it to hook-up so why not have some fun banging gears?? If memory serves, all of the BOP related parts should interchange. Perhaps a GM tech type will jump in and then I can ask the same question about the Cad 500......
get yourself a bop bellhousing , and the correct flywheel for the 425 olds....and the rest is standard gm stuff....
do some research first, I may be mistaken but I don't think the 425 was offered with a manual trans behind it...............my friend had a built 425 in his 69 cutlas 'vert with th400; well, he found a wrecked 442 with 400 4spd and the plan was set to swap the 4speed behind the 425. All was going smooth as ****er until we discovered the 425 crank was not machined for a pilot bearing/bushing. We did finally get the job done but it was more involved than our original saturday project.
The 401/425 was offered with a 4 speed hehind it, however; this was a very rare option. You will require a 4 speed starter which is not standard GM stuff, as the 4 speed starters have a different nose length on the starter as compared to the automatic. The pilot bearing will have to be machine out of br*** for the end of the 401/425 crank. "Offy" does offer two adapter plates which bolt together to form the bell, using a long style release bearing out of a 50's Chev P/U. OR, you can now purchase a complete kit for the 401/425 nailhead to a 4 speed which solves all of your problems of matching parts together.......
listen to duffman. you gotta have the crank machined for the pilot. you're looking at lots of searching, fabricating and a hefty price tag on all the goodies to do that unless you find all the stuff in a car you can get cheap...good luck on a cheap 4sp BBO of any kind i'm running a switch pitch behind my 461 olds i'm putting in my truck. just got the sp this morning in fact...love the u-pull it yards
Whatever you do DO NOT use a Saginaw four speed behind the 425. The torque of that engine will shred the Saginaw the first time you hit the gas.
What stepchild and duffman said. The 425 is a great engine, factory forged crank, short stroke compared to the 455 and 68 up 400. You'l love it.
Sorry I didn't read the post, I'm talking NAILHEAD as I built one of these three years ago for a model 'A' coupe which I have since sold. The buyer removed the 4 speed and put an automatic in this rod. All the parts (Offy plates, flywheel, pilot bearing & starter) can be purchased from a fellow named Steve at (905) 839-4422 in Ontario, Canada...
Wow, thanks for the responses guys, the work seems like it would be a little more involved than I had originally thought however I think I may still roll with it since it will be a little while unfortunately before it all gets bolted together. Though as soon as I do pics will be posted. As it sits now chadillac its simply an A frame on a table with the body lying next to it, with parts ****tered across nebraska. However the body is without the bullet holes now.
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