I'm a new member and this is my first conversation here, so don't be too hard on my endless rambling of mixing a intro background story of sorts into the points of my questions. What I have is a '55 Olds 4 door post that I drug out of a farmer's field. This car has been through hell, and unless Jay Leno himself buys it someday, it will never be a Barrett Jackson level car. A properly restored 4 door Super 88 like mine is worth about a third of the investment. I could buy a decently restored one of these on Evilbay for what I could easily spend on this car at a body shop. As a gearhead, we all know it's not about that. This car is worth saving and my intent is to save what's here, and make a decent car out of it on a budget...without being "that LS swap guy". Most old cars are parked 'that last time' for a reason, and mine that had sat since the mid '70's is no exception. Once the two garbage can fulls of mouse nest was cleared away, aside from the cancerous front floor pans, and powdery, disintegrating foam option seats, this car isn't all that bad. It was hard to believe the engine ran as well as it did. It had a smooth idle and after about an hour of run time, the smoke was clearing up, but the upper end was too noisy for my comfort. Investigating the clatter in the original 324, I found that the camshaft had taken on the texture of a rotary file. With little choice, I pulled the engine and tore it down for further inspection. A .070" feeler gauge slid right in between the (ridge-less) cylinder wall and piston skirt...well then, here we go... So I started weighing my options for rebuilding, versus a family members offer of an available 455/TH 400 to swap into this car. Not sure what my problem is, but I am just too sentimental about wanting to keep this car a '50's vintage car. About that time I came across a smoking deal on a partially rebuilt '59 394 basket case on craigslist, that came with a dual coupling hydro. To have a proper era gen I rocket sitting proudly in a gen I car, and have that 4.125 bore with vastly better breathing heads, the 100+ HP and torque gains, plus little perks like a window for setting points, a screw on oil filter, etc. Well, to me is the best of both worlds. However, I want to use the dual range hydro that is in the car with the newly acquired 394, and here lies the problem. The problem with this is the original 324 engine is internally balanced, whereas the 394 is externally balanced. The 394 also does not have the pilot shaft provision needed for the Dual Range input shaft cut in the crank (yet). I read through some really old threads on here that say it's fairly simple...just balance the dual range flywheel and have a pilot hole cut in my 394 crank. Sounded easy enough until I visited my local machine shop. They want to rebalance the 394 via the crank counterweights, as well as charge a king's ransom (over $200 just to cut the pilot bearing hole..about $800 in all- seems a bit steep). Money aside, I don't like this idea as it ruins the 394's balance for any use other than for this one setup. I have also considered exploring the possibility of sending the crank and components off to someone who for certain knows what they're doing, such as Ross Racing, but this crank by itself weighs about as much as a mail Jeep, and I know how carefully heavy items are shipped...and so... My debate now is whether I should seek a second local opinion on the balancing. I just want the flywheel balanced to work with the 394 (like the one that came off of it)...not the whole engine into some sort of oddball balance nightmare to work only with this trans. I'm not experienced in engine balancing, so I don't know if they have enough room on the flexplate/flywheel for the weight needed. Or should I just forget about adapting the Dual Range Hydro to my 394 and put the untested Jetaway (dual coupling) trans back on the engine it came with? With what I've read, it seems the Dual Range is a better (more desirable) trans, I know it works, and the old dual range "jerkomatic" has a much more solid feel to it than the Dual Coupling ever would. So now to my questions: Since using the Jetaway is virtually a bolt in swap, (easy way out- other than cooler lines and the added P selector that the '55 indicator doesn't have) is the dual coupling Jetaway that much worse to use, being that I already have one of these in the bag? Or is keeping the Dual Range Hydro (which I prefer) worth the nightmare of making it fit a 394? In my experiences, most car guys get this glazed over cross eyed look and the gears in their heads grind to a zombie like halt whenever anyone starts asking them technical 1st or 2nd gen Olds Rocket questions. Hoping someone can help me decide the best direction to go with my conundrum.
Contact Tony Ross think it's handle is goat roper he knows all about these things so you can cut right to the chase Sent from my SM-J737T using The H.A.M.B. mobile app
Dual couplings are strictly for restoration freaks. They were only made for a couple years then junked for good reasons. Make the effort to go dual range.
I don't know what is available for the Olds 394, but what I would do first, would be to contact Wilcap, Bendtsen's, and B&M. I am willing to bet there is an adapter available. As for the quote for drilling the crank, I think the price quoted was a ripoff. It is testing my memory, but the 59 should not be as much of a problem as the 61 or later Olds engines. Here is some more reading for you. https://forums.aaca.org/topic/63531-1963-hydra-matic-interchange/ Bob
Don't confuse the '56 up hydro with the '61-'64 Roto-Hydro/Slim Jim disaster. The Jetaway is reliable as an anvil when maintained. It just doesn't have a personality compared to a '52-'55.
I would contact @Paul on here, he will have the answers to your questions. I prefer the Hydro, but as 302 GMC stated, a Jetaway isn't bad either.
Fyi, the Jetaway dual coupling came out in 56 and was produced all the way thru 1964. The Roto Hydro came out in 1961 and was produced thru 1964. Not near as good as the Jetaway.
The swap you're considering was a pretty common deal back in the early-mid '60s. I had that combo in my '55 Chevy Carry-all (Suburban). Should make for a nice sleeper. I think I would proceed with the old Hydro. The 394/Hydro conversion has been done thousands of times over the years so I'm sure the information is out there. If you've got the 394 apart to drill the crank now is the time to get it all balanced. Around here, balancing is $250 - $350 for a V8 depending on how bad the junk you drop of is. I would shop around if you can, your guy is mighty expensive. Another factor; there is more info available for the Hydro vs the Jetaway should you want to make improvements in the trans in the future.
There were never any performance/racing transmission builders that built Dual Coupling Jetaway transmissions, so I think that says a lot. I'd use the old cast iron, Dual Range; those were built for racing back in the day. \I am Butch/56sedandelivery.
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