The Great Drivetrain Swap

We had the wagon’s 435hp 383 swinging from the hoist in an hour and a half, and the swap was on. Problem number one: Swapping the engine-mount towers took half a day because the bolts are hidden under the lower control arms.

The Biscayne’s greasy, wheezing 230ci six-banger came out with the column-shift three-speed attached. It leaked oil like the Exxon Valdez but ran strong to the end and propelled the two-ton Biscayne with surprising get up and go.

We had a turbo 350 running in the wagon, so we swapped the 383’s flexplate for a flywheel. Our 383 is kind of a crossbreed, balance-wise, that uses a neutral balance damper but requires an externally weighted 400 flywheel at the back of the crank. Virtually impossible to find at a junkyard, fortunately they can still be obtained new because they’re popular in circle-track racing. We ordered a 168-tooth billet flywheel from Hays, which required parts-run number one to the local Kragen for longer Grade 8 flywheel bolts and a pilot bushing. We also ordered a Hays 11-inch pressure plate and high-performance street/strip disc with a 26-spline input-shaft pattern to match the Richmond Super T10, which bolted directly to the new flywheel.

By Wednesday, the engine and trans were finally ready to swing into the Biscayne, but it rained off and on all day so we ended up lying in a puddle of rain water on our backs bolting in the engine mounts and crossmember, only to find that we couldn’t get the clutch to adjust properly.

Problem number two: the nose of our 168-tooth-pattern starter was too large to fit into the recess in the bellhousing. Through a stroke of luck, we just happened to have a couple of extra Chevy starters in the garage, including this large-pattern unit with a cast-iron nose from a ’72 Chevy truck with a big-block. Although both have the staggered bolt pattern, the size of the nose differs between the aluminum and cast-iron versions. Until this moment we had no idea there were more than two Chevy starter variations, and to be perfectly honest, we still don’t know the specifics of the various applications. We’re just glad we had the right one to solve this problem. Problem number three: the cast-iron starter uses odd-length mounting bolts, which we’d lost, and we had to make four trips to parts stores before finally ending up at the local Chevy dealer to get the right ones.

In anticipation of this swap, we had scrounged a Chevy bellhousing from a late-’70s Camaro at a junkyard. This later-style bellhousing accepts the larger-diameter clutch and flywheel we were using, but there were complications (see Clutch Craft sidebar). Problem number four: The clutch Z-bar didn’t clear the shorty-style headers we had used on the wagon because the collector is too close to the block pivot on the driver side (arrow). Fortunately, we had a set of generic long-tube headers at the Car Craft shop leftover from an old dyno test that fit. Even though the steering box on ’65-’70 fullsize passenger cars sits behind the crossmember and steering linkage (rear-steer), these cars accept headers designed for front-steer Chevelles and early Camaros, and most header companies actually catalog all three under the same part number.

Richmond’s brutally strong 2.43:1 First gear Super T10 presented few interchange problems because the trans mount is in the same location as the mount on the Biscayne’s original three-speed. Super T10s replaced Muncies in the mid-’70s and variants are still used in Winston Cup stockers; they share many features of later-style M21s, including the 26-spline input shaft and larger TH400-style output shaft. The Richmond is about an inch longer than the Biscayne’s three-speed, however, so we had the driveshaft shortened and modified to accept a larger U-joint.

Hurst’s legendary Competition Plus four-speed shifter is still available for fullsize Chevys, so we grabbed one up and cut a hole in the floor with a Sawzall to clear the mechanism. We had hoped to use this cool older-style handle that we found at a swap meet, but it didn’t clear the bench seat, so we stayed with the shorter handle that came with the shifter.