How to assemble a race-ready drivetrain

Tim
By Tim Suddard
Dec 9, 2022 | Ford, Mustang, Ford Mustang, Drivetrain, Project car, Vintage Race Car, Cobra Automotive | Posted in Features | From the Nov. 2022 issue | Never miss an article

Photography by Tim Suddard and Chris Tropea

Our 1965 Ford Mustang vintage racer lacked something rather crucial when it fell into our lives: a driveline. Popping the hood revealed an empty engine bay–but also potential, too. 

We were going racing and needed to fill that hole with something suitable. We did the math and found that buying a used race engine made the most sense. 

The world is littered with small-block Fords, so we asked ourselves some questions to narrow the field: Is it legal? It is bona fide? Is it complete?

Is It Legal?

We plan to race our Mustang with a few different organizations, but we’re primarily letting HSR’s rule book guide us. The rules for our class–Group 3’s Vintage A-Sedan–require either a 289- or 302-cubic-inch Ford V8. It has to be an iron block topped with iron heads. 

The 289 gets a weight break: 2700 versus 2800 pounds. While that hundred-pound advantage sounds enticing, the reality is that you’re just not likely to get an early Mustang down to 2700 pounds. We figured we might as well go with the bigger engine. 

Is It Bona Fide?

We realize buying a used race engine is a gamble. Does it still have some life in it, or is it a few laps from expiration? 

Cobra Automotive’s Curt Vogt has been helping us with this project–his shop’s Mustangs are legendary in vintage racing circles–and he had something enticing on the used rack: a Group 3-legal Ford 302 engine out of a 1967 Cougar. The engine’s prior owner decided to move up to the faster Group 5 class. 

It was originally built about eight years ago but had seen less than a hundred hours of use since its latest rebuild and refresh. Cobra Automotive promised that it made 500 horsepower and 393 lb.-ft. of torque. The price: $7500. 

Is It Complete?

This engine came nearly complete–it just needed the headers, alternator and carburetor–saving us considerable time and money.

Our used race engine sported lots of proven hardware, all bought for pennies on the dollar. 

Fitting That New Engine

Although the folks at Cobra Automotive make their own equal-length race headers, Curt recommended a less expensive, mass-produced route for us, reasoning that we weren’t going to run at the pointy end of the field. He suggested a set of Hooker headers–not quite $600 instead of close to $4000 for the race pieces–but noted that we’d need to modify them.

1. Our new Hooker headers needed some modification to be used for racing. First, we cut off the collectors and reconfigured for a slip fit. Curt also suggested removing the heat rider tube since it wasn’t necessary and just added weight. 

2. Curt warned us that the mounting surfaces might not be straight. One side was perfect. One side was not.

3. We sanded the imperfect flange on a large shop belt sander and quickly got the header into spec.

4. Our engine uses World Products heads, which slightly reorient the spark plugs for increased performance. We needed to modify the headers for clearance using heat and a piece of pipe as a die. (Don’t directly hammer the header, Curt cautioned.)

5. The new headers were beautiful, but Curt told us that the factory coating wouldn’t survive in a racing environment. His advice: Get the headers recoated by a specialist. We had Swain Tech apply its White Lightning high-temp finish. Richard Tucker, the company’s owner, said it’s common for radiant temps to reduce by 30% to 50% when measured an inch away from the surface.

Transmission Time

Don’t install a used transmission in the race car, Curt begged us. His reasoning: An unknown box could lock up at the worst possible moment, immediately derailing an entire weekend. 

6. Curt recommended we spend the $4000 or so for a Roltek T-10. This Chevrolet-based T-10 four-speed is legal for our HSR class–no five-speeds allowed–and has been extensively modified to be lighter, stronger and easier to service than a stock T-10.

We also ordered the company’s FIA billet shifter kit designed specifically for the early Mustang. At more than $500, this shifter seemed a bit pricey, but Curt insisted this was another instance of money well spent. Missing shifts at high rpm can be even pricier, so we took his word for it.

7. Instead of a stock-type, 10-inch clutch, Curt said to run a two-disc setup. This twin-disc, 7.25-inch Tilton race clutch should easily deal with our engine’s 500 horsepower. Plus, it’ll save weight.

8. We used ARP hardware anyplace we could, especially in critical locations–like securing the superlight Tilton flywheel to the Ford automatic transmission flex plate required for this swap.

9. Our Tilton flywheel was also bolted into place with ARP hardware. This entire flywheel/clutch assembly weighs a little more than 12 pounds; the stock assembly is more than 40 pounds.

10. With everything assembled–and the radiator and shifter out of the way–it was easy to drop the driveline into the Mustang. We secured our modified transmission mount with grade 8 bolts. Everything bolted together perfectly.

11. In addition to fitting the radiator, we topped the engine with a new Moroso air cleaner. Next, we’ll start working on our suspension, rear end and power steering system.

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stonebreaker
stonebreaker New Reader
9/30/22 3:16 p.m.

You guys should put a cold air intake on that carb instead of inhaling hot engine bay air.  Get it from the base of the windshield ala' NASCAR for the highest pressure location.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
9/30/22 3:33 p.m.

In reply to stonebreaker :

It's a Shelby, Carrol knew everything :)

te72
te72 HalfDork
9/30/22 10:47 p.m.

Seems like I did everything wrong with my Supra build haha. "New" built engine, used transmission... oops. Can confirm, used transmission isn't the best idea unless you plan on a rebuild anyway.

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