THE AUSTIN T PARTY: RUNNING THE NUMBERS or
THE TALE OF THE MISSING EAR.
I decided to do some sleuthing to determine the exact drivetrain beyond the info provided by Ian Loska when I bought his 1929 roadster over a decade ago and got the drivetrain that will soon be powering "Lily" out of the deal.
So I headed out to the garage, pad in hand, and pulled as many ID #'s as I could find from the engine and trans:
I recall that Ian Loska mentioned the engine and trans came from a wrecked ‘66 Buick he’d scored off of Craigslist in So Cal. According to Ian, it had been rebuilt just before being totaled due to a freak accident that involved a lady's Buick rolling out of her driveway, crossing a rod and becoming intimate with a neighbor's tree. Ouch. Weird, the stuff you remember. We’ll call that detail #1. I also remember one of the many quirks I loved about Ian’s car when I test drove it in L.A.was that he'd rigged a pushbutton that acted like a transmission kick-down to his Turbo 400's 3-speed.
We’ll call that detail #2. Unfortunately, I totaled the car ten days after it arrived. We'll call that a detail I'd rather not get into other than to say it was an unfortunate situation that wasn't my fault but led to a protracted battle with Liberty Mutual Insurance, who tried desperately to screw me. Raging assholes. There, I said it.
Back to fonder memories.
I remember that the Nailhead and Turbo 400 in Ian’s roadster had quite a bit of scoot for a car with a factory Buick 12-bolt with “freeway” gears. I’m guesstimating 2.73 or 2.93, which were both common to Buicks back in the sixties.
Nevertheless, that "kick-down" switch really woke the car up. I now realize that what Ian had behind the nailhead was a “Switch Pitch” or “Variable Pitch” Turbo 400, which is a rather rare variant of an otherwise common transmission.
Good news for me. We’ll call that detail #3.
After a little web-surfing, I found the final clues that solved the engine’s year, if not but its exact cubic-inch displacement.
Here’s what I found online that sealed the deal on the engine. In 1966 only, Buick had an “ear” on the rear of the block. It was a circular hook which no doubt made maneuvering the engine easier and installation more efficient. I also learned that the block has a casting mark adjacent to the ear that identifies it as a 401/425.
Here are the numbers I pulled from my engine:
Bell housing Engine #: B1364705 = 401/425
Heads: 374603 = 401/425
Intake: 1375549 = 401/425
Valley Cover Stamp = Partial stamp. Unreadable.
Factory Casting Stamp Block = Rectangle = 401/425
THE ENGINE IS DEFINITELY A 1966 401/425.
BUT WHAT ABOUT THE TRANSMISSION?
I pulled the following #s off the transmission’s ID tag. “125. 89FYA. 5365.” Further investigation revealed that the transmission is a 1966 Turbo 400 “Switch Pitch”.
Badass.
That explains the push button switch that I thought was merely a downshift. What I hadn’t realized at the time, was that I was experiencing a feature that GM engineers had pioneered on Cadillacs, Buicks, and Oldsmobiles, from 1965-1967. The “switch pitch” gave the driver the ability to alter the torque converter’s stall speed for more pulling power such as on a steep grade. Damn cool. After just three years, GM’s bean counters phased out the switch pitch option, but 60’s racers and street rodders used it to their advange for years. It was a shade-tree performance hack that blew a lot of minds to be sure.
Never mind that it allowed a large Buick engine to deliver far better gas mileage. What it also allowed was the off-the-line performance of a far steeper gear, while simultaneously offering the enhanced gas mileage form Buick's "highway" gears.
Further reading also pointed out that having a good transmission cooler is to vital to keeping the “switch pitch” happy. Good to know.
SPECIAL THANKS TO RUSS MARTIN FOR A LOT OF GREAT INFO.
If you'd like to learn a shot ton about Buick nailhead or find a great selection of hard to find parts, check out Centerville Auto Repair and Russ's excellent collection of Nailhead tips, knowledge, and parts.
Can’t wait to get this switch pitch back and nailhead back on the road. So there you have it. Lily’s drivetrain is a 1966 401/425 Nailhead with a 1966 Turbo 400 Switch Pitch trans.
NEXT UP: IT’S ALL IN THE DETAILS.
Pulling the engine and trans for a deep cleaning, deburring and prepping for paint is in the near future. Then it’s time to play dress-up. Thanks for taking a T break with me.
INSPIRATION. STAY TUNED.
