The Mystery 427 Chevy Engine Used at the 1963 Daytona 500

Greg Zyla
Q: This is an updated response to the Mystery 427 Chevy engines. The engine in your photo is actually the 427 mystery engine my dad, Louie Clements, built for Rex White to run the 1963 Daytona 500. That engine pulled 540 horsepower 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 1963 season. GC Spencer bought the 1963 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 1964 Season.
Mystery 427 Engine at the 1963 Daytona 500 
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. 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.
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 1963 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, (
Rex White and Louie Clements with the First-Ever 427 Mystery Car 
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 Amazon.
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 1963 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!
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