Cars We Remember 1963 Chevrolet Impala Mystery 427 Chevy Engines

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Rex and Louie with first ever 427 Mystery car-u
Here’s NASCAR champ Rex White, behind the wheel, and good friend and crew chief/partner Louie Clements, who was the official builder of the first two 427 Mystery Motor 1963 Chevy Impalas commissioned by GM. They are shown here at GM’s testing grounds in Mesa, Arizona. Mike Clements, son of Louie, explains all in this week’s column. (GM historical photo). (click to enlarge)

Louie Clements son, Mike, responds to Mystery 427 article

Q: Hi Greg, just an FYI on your article on the Mystery 427 Chevy engines. The engine in your photo is actually the engine my dad, Louie Clements, built for Rex White to run the 63 Daytona 500.

That engine pulled 540 HP on the dyno a couple nights before the race.

Just before the July 4th Daytona race, my dad gave this engine to Junior Johnson to help him complete the 63 season. GC Spencer bought the ’63 Chevy race car from my dad and Rex and ran a 409 in it.

It wasn’t competitive so he switched to Ford for the 64 Season.

Also, thanks for your writing efforts. I am now 63 years-old and reading everything I can find about the early years of NASCAR. You are right about the Mystery 427 engine.

Workers in Junior Johnson’s garage at Daytona in 1963 get ready to install a brand new 1963 427 NASCAR Mystery Motor. (Photo courtesy Junior Johnson). (click to enlarge)

Most NASCAR “historians” claim there were 48 complete engines built, but my dad, (Louie) and Rex (White) were at Smokey’s (Smokey Yunick) shop when the big truck from GM dropped off the engines.

They both counted only 14 engines, which sounds much more believable and relates to your story about Smokey telling you how they would switch them out to another shop real quick to fool NASCAR inspectors. (NASCAR rules mandated 50 had to be built for race eligibility).

GC Spencer, by the way, passed away about 10 years ago. His son, Terry Spencer, and I have been friends since grade school and today Terry owns and operates a transmission repair shop in Inman, SC.

Photo (above) Mike Clements, whose father built the ’63 Chevy Mystery Motor cars driven by Johnny Rutherford and Rex White, sent this information in our the photo we ran a few months ago. In the photo, notice half of the name “Clements” on the creeper against the work bench as, left to right, you see James Hylton, Dean Hall, Ken Miller, Slick Owens and a Chevrolet factory representative. This particular engine went into Rex White and Louie Clements No. 4 Impala. (NASCAR photo).


My dad and Rex received only that one single engine that was in their car after the Daytona 500, and they had to run all year on that one engine.

By July, Louie gave that engine to Junior (Johnson) to help him through the season. After GC bought our No. 4 gold and white car, Bill Stroppe gave my dad and Rex White a brand new 63 Mercury race car when they showed up for the ’63 Firecracker 400 at Daytona.

Here’s an interesting note: The black and gold Chevy that Smokey ran at Daytona was actually built by Rex and my dad (Louie) at their shop in Spartanburg, SC. Chevrolet paid them to built two cars for testing at GM’s Mesa Arizona Proving Grounds. After the tests were complete, GM sent the red car, (one was red and one was white) down to Florida for Smokey to run in the 500.

He hired Johnny Rutherford to drive it. I hope this helps you, good luck in your writing and thanks for writing about the Mystery motors. Mike Clements, (

A: Mike, much thanks for your input on this still popular period of time in Chevy’s auto racing history. I also want to let my readers know up front that Mike has a new book available titled, “The Crew Chief’s Son” which tells the story and all the details about the “Rex White and Louie Clements” racing history. It’s available from McFarland Publishers or on

I didn’t know that only two Chevy test cars were built for the Daytona 500 for Chevy, and that you and Smokey received them after your dad built them. I do know the Daytona 500 lineup featured several other ’63 Chevys that had the Mystery Motors, including Junior Johnson’s two entries, his No. 3 and the one driven by GC Spencer numbered 03.

For the sake of the readers who may have missed my initial Mystery Motor column a few months ago, I’m re-running the garage photo Mike notes of along with another rare, interesting photo. In ending, I want to thank Mike Clements, and wish all the luck with his book and engine building business. I’m ordering my book right after I finish this column!

(Greg Zyla writes weekly for More Content Now, GateHouse Media and He welcomes reader input on collector cars, old-time motorsports and auto nostalgia at 116 Main St., Towanda, Pa. 18848 or email at


Legends of NASCAR – Louis Clements

409’s in NASCAR – Rex White


Greg Zyla

Greg Zyla