I found a TH400 for my 425 nailhead. It's a 64 and has some ultra rare valve body gasket, but it's in good condition and being rebuilt. I have the engine, and the engine has a triangular thing bolted to the crank. I don't, however, have a flex plate or torque converter. Anybody know where I can get such an item? Does the flex plate attatch to the triangle thing? Or is that for a flywheel? I have no manuals or any experience with this engine.
Flexplate Bob, That triangular thing is the flexplate for automatic transmission equipped Nailheads earlier then 64. The 63 and earlier cars used the dynaflow transmission that has a ring gear for the starter on the transmission converter. The 64 and up Nailhead transmissions attached to a more traditional flexplate that has the ring gear for the starter on the flexplate. There are several options for using use the later (64+) transmissions with the earlier engine: Machine the hole in the center of a later (64+) flexplate to fit the larger crank flange of the early (63 and earlier) Nailhead. You will also need a bushing to support the smaller converter end that rests in the crank flange. Carmen Faso has these, and is one of the parts providers in the sticky thread at the top of the Nailhead forum. Machine down the crank flange of the earlier Nailhead (63 and earlier) to acept the later flexplate. This will still require the bushing mentioned in the methood above. Swap in a later 401/425 (64+) crank and flexplate into the earlier engine. You would use a main bearing set for the earlier (63 and earlier) Nailhead engine in this swap. I would use the balancer from the donor engine as well. I think any of these methods other then the last (most likely that one too) would warrant an engine balance with the parts you intend to use. I would bet that your engine is coded JW if it is a 425 with a triagular flexplate. Cheryl
Thanks Cheryl, Near as I can figure, the engine is a 65. I don't have the code right in front of me but I did look it up before on some Buick link that went to a bunch of engine codes. I'll have to look again. I don't suppose you know where to get one of these flexplates do you? Does Carmen Faso have just the regular flex plates? Thanks again.
More Help Bob, I would put an ad for a 1964-1966 Nailhead flexplate in the parts wanted section of this site. I don't know of a better place to find one. Carmen would have the bushing you will need for the crank. Please check to see if your crank flange is 2 7/8" in diameter before you do anything else. That is the size of the early (63 and earlier) Nailhead crank, and it would be good to establish what engine you have before doing anything else. The later crank measures 2 1/2" across the crank flange. Cheryl
Well, I looked at the crank and the flange is 2-7/8" but the number stamped on the front of the block seems to indicate that the block is a 66. I looked at buicks.net for the code and the number stamped on the block reads as follows M (1" space) W255 (1" space) 6H924052 with the spacing more or less like above. I assume that it's an MW engine which should make it a '66 425. Maybe someone put an older crank in it? Whaddya think? I guess I'll have to machine a newer flexplate and get the bushing regardless.
Bob, Looks like someone wanted to power a dynaflow equipped car with a 425 and swapped in an earlier 401/425 crank. Your #s are consistent with a 1966 425. MW is for 66, 425 CI, single 4 bbl (Quadrajet). 6H924052 are the last eight digits of the car vin# the engine came from. The 6 is for 1966, H is for the Flint, Mi assembly plant, and 924052 is the number of the car in serial order. It appears you have the task of swapping it back using one of the methods above. In this case, you would use the 64-66 main bearings if you swap cranks back. Life is often undoing the doings of others. I guess we cant even expect a Nailhead to be immune to that? Cheryl
You can't argue that bit of wisdom, Cheryl, very profound indeed. It turns out I got a spare crank with the engine that I was told is for the manual tranny which has the 2.5" flange. Whaddya know, I'm all set assuming that there isn't a different manual vs auto crank. I was thinking of taking it apart anyway just to make sure the bottom end is solid. Maybe I'll just put the other crank back in and go from there. I've located a flex plate, now I just need a torque converter. Thank you so much for your help here, I've a lot to learn about this baby. You wouldn't happen to know a source for service manuals for the nailhead would you?
that brings up an interesting question--does anyone know if there is a different crank for the manual transmission cars in '64-'66? I always thought they were the same.
Manuals and Cranks and Bushings, Oh My! Bob, You could try a search for Chassis Service Manual on Ebay, or purchase one of these. I also had good luck with the guy in this post. He may have some left. The Chassis Service Manuals have also been converted to disk. Here is a link a Chassis Service Manual on disk, and this is another. Brian, Cranks were are all the same from 64 to 66. The manual equipped cars had a pilot bushing pressed into the crank hub. This thread has more information on the Nailhead cranks and pilot bushing. Cheryl
Thanks Cheryl--good information on the cranks! One more question though--do you know where I can find one of those manual transmission pilot bushings for the crank? I put my '65 GS together with stuff from two cars--mine was an automatic and I took all the 4-speed stuff (as well as some body parts) from an engineless parts car. As a result I had no pilot bushing for the engine. I ended up making my own by fitting it all together, making a bunch of measurements and then machined it out of bronze on my lathe. If I could find an original I would love to get my hands on it. You can E-mail me at Stonesautomotive@juno.com
Thanks Ted! I will give him a call What did you ever do with that 3.23 10 bolt out of your '65 Wagon?
You will be the first to know about those gears when I get them out. Still working on my 70 trannie, the Waggone is next. Thanks, TN