[tripower]

Anyone know what year Tempest John Delorean installed the 389 into to test his idea for what became the 64 GTO? If the first GTO rolled off the assemble line around 9/11/63 (about 8 days after production started), would it have been a 63 Tempest that he and friends tested with the 389? Imagine finding that car....

[tom s]

MT and Haydon put a 421 in a 62 tempest.The factory built 14 SD 421 tempest in 63.Not a good compare as the 61-63 were unibodies and the 64 was a frame car.Tom

[Keith Seymore]

It was a '64: mainly because Bill Collins said so in his memoirs.

Start of regular production for the '64 model year was the day after Labor Day, 1963, but that would not preclude having a bunch of pre-production '64 A bodies around that were used expressly for development purposes.

I recall reading it was tan/beige or some other fairly nondescript color; I also recall it was so well received that Delorean had a little trouble getting it back after he loaned it out for evaluation and use.

K

[John V.]

The story as I've heard it told in the past can be found here.

https://www.hagerty.com/articles-vid...o-origin-story

Definitely a '64 and likely a Lemans Sports (post) Coupe since the Hardtop didn't materialize until weeks after the start of '64 production.

As Keith says, it would have been a pre-production build, the article calls it a "test mule". Time frame is not indicated but based on other dates associated with the planning for the '64 GTO, the 389 probably was installed in that "test mule" Lemans at least a couple months before the 9/3/63 start of '64 production and perhaps even earlier than that.

Given the production of the '63 Super Duty Tempests, it actually seems like it shouldn't have taken much imagination to consider the 389 for the '64 A body. And everybody at PMD would have recognized the dimensional similarity of the planned 326 and the 389 engines.

The real trick was how to make it available to the buying public without GM Corp. putting a quick end to the idea. The option loophole got that done.

So why didn't they go all the way with a 421 instead of the 389? Maybe they figured heads would roll if they tried to snooker GM Corp. with a 421 given the '63 racing ban edict.