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Tight Fit: Squeezing a 390 into a Cougar

Tight Fit: Squeezing a 390 into a Cougar


The owner of a like-new ’67 Mercury Cougar put an extra hole in his cylinder head and sent a valve hurtling into the block. As a result, ugly cracks appeared in the cylinder walls and pistons. This resulted in replacing the old California emissions block with a different “49 states” block that was fitted with Edelbrock heads and fat 429 Ford exhaust manifolds. The stock 390 was always a tight fir in the sport-compact Cougar’s engine bay, but the mods the owner did made us wonder if we’d need a shoehorn to do the install.

We brought in extra help in the form of Dave Sarna, a recently retired automotive technologies instructor at Fox Valley Technical College in Appleton, Wis. FVTC student Heidi Schaefer was also involved along with our son Jesse. Christy Edelbrock helped us secure the new heads and they fit perfect with all of the holes drilled in the right places and all mating surfaces perfectly designed and machined. We’re not sure if the new heads “grew” the engine slightly, but we knew that the fat 429 headers added width to the power plant. By measuring the width of the engine and the distance between the inner fender wells, it looked as if the engine would go in, but who could say for certain.

Just because the engine had sufficient clearance at one certain point didn’t mean the 390 could be lifted in and slid back to that point without hitting something else. Luckily, car owner worked for Ford and had access to old engineering drawings as well as contact with engineers who worked at Dearborn in the ‘60s. He was told the modified engine could be installed by using a trick. The technique involved removing the right-hand exhaust manifold during the install. Then, with the bolts held in the holes with tape or goo, the right-hand header could be reinstalled once the 390 was sitting in the engine bay on a tranny  jack.. With the engine out of the car, the flywheel was installed. Then our team installed the flywheel reinforcement plate we purchased on eBay for $23. (This simple part—used only on automatic transmission cars—had been left off the last time the engine was rebuilt and the result was a bent flywheel that went out of balance.)

With the flywheel and reinforcement plate installed, the team attached our Eastwood engine balancer to the engine hoist and lifted the engine in place, checking to be sure the two dowels in the block engaged the flywheel housing. Since the car was automatic—the converter pilot was started into the crank  Next, the converter housing upper bolts were installed.  The team then removed the tranny jack and lowered the engine until the front mounts were properly supported in the brackets. Then, the right-hand mount was torqued down. And the engine was unhooked from the hoist. The Cougar was then raised a little so the rest of the flywheel housing to engine block retaining bolts could be torqued to spec. Then, the engine mounts and their brackets were torqued down.

After everything was tightened, the right-hand exhaust manifold was replaced in the manner previously mentioned and the bolts were lined up with the holes and tightened. “We worked with one person on the top and one on the bottom,” said Jesse. “It went smooth, but it seemed to take forever to get the last manifold bolt in; it felt like we turned it 100 times before it tightened.” The balance of the job will involve installing a fat stainless steel dual exhaust system bent up by Waldrons Exhaust and attaching the various engine accessories such as the starter, A/C compressor and power steering pump. We’re looking forward to finishing the project, but we’re really glad that the first step of squeezing a big engine into a relatively small car is over.

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