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Building a performance engine from scratch – especially if one has never done it before – can be a daunting task. So when Wisconsin resident Ryan Carufel set out to put this Pontiac engine together for use in his 1966 Catalina, he had no idea what to expect. As his first-ever performance engine build he made some of the mistakes that can only come from inexperience, but in the end he managed to put together a sweet Pontiac bullet that will prove to be solid motivation for the nine-year project he’s embarked upon. Although the car isn’t finished yet, the engine is, and he shared the details of its construction for EngineLabs first Homegrown Horsepower feature.
“I had gotten a 1966 Catalina from my grandpa, brought it home, started restoring it, but found out it was too rusty to continue working with the original car. So I bought a different frame, and a different body. And then at that point, I figured since it wasn’t the original car, do I go with the original engine? I might as well go with the biggest engine I could,” remembers Carufel. “I happen to have a friend, Cole, that back in the 70’s had an outrageous Pontiac collection – the only thing he had left of that collection was this engine. It was out of a 1970 GTO that was totaled by his brother, and this engine was the only thing remaining of that car. I was intimidated at first looking at the engine, as this was my first engine build. The only experience I had with a Pontiac engine was taking the valve covers off.”
The Pontiac Tri-Power is one of the first real musclecar engines and differs from most engines of the era in that it could provide 326 cubic inches all the way up to 455 cubic inches with only an internal change in bore and stroke – the block remains the same throughout that cubic inch range. The 455 variant utilizes undersquare dimensions (the stroke is long relative to the bore size) and offers up an incredible amount of torque, which was emphasized over horseower in those days.
The engine was subsequently dropped off at a friend’s house, who disassembled the engine and took it to a local machine shop to be cleaned up. It was originally planned to be a budget build with the only machine work performed designed to correct any deficiencies, along with a new set of rings and bearings scheduled to bring it back to its former glory. After ten months of the engine sitting at the machine shop, Carufel picked it up and took all of the pieces home.
During this time period (as he didn’t expect it to take nearly so long to perform the machine work) Ryan was banking more and more money to put into the engine. This bankroll, and the decision to build a strong base for his first-ever performance engine build, resulted in the purchase of an Eagle Specialty Products stock 4.21-inch stroke forged crankshaft and Oliver I-beam 6.625-inch forged connecting rods along with a set of Butler Performance-spec Ross forged pistons.
Although the initial plans for this build called for a budget-based approach, the end result is an engine that will handle whatever is thrown at it, thanks to the use of a forged crankshaft, connecting rods, and pistons.
The engine is based around a 1970 Pontiac 455 4-bolt-main block and #64 cast-iron heads with 92.6cc chambers. The cylinders had been overbored by the shop to measure 4.190-inch (.040 over stock) and provide a final displacement of 464 cubic inches or 7.61 liters.
“My goal was to provide a strong reliable engine that could withstand pounding yet get decent gas mileage if I kept my foot out of it. It also needed to have tons of low end torque to move my 4,000 lb car around. I wanted to keep my options open so if I ever decided to make some serious horsepower, I’ll never need to wonder if my bottom end will be strong enough,” he says.
One initial thought of the build with the 455 included making the engine look like a 389, so that when he popped the hood on his Catalina, everything would appear period-correct, and this portion of the build proved to give him fits. “The timing cover is different, the exhaust manifolds are different, the oil filter housing is different – it all mounts up to the same places on the block, but appears visually different. I finally got everything straightened out, but the last thing I had to do was the intake manifold,” he explains.
Tri-Power tuning was handled by the experts at pontiactripower.com, and resulted in a carburetion system that performed exactly as advertised on the dyno.
The intake manifold, and the attendant Tri-Power carburetion system, proved to be one place where Ryan felt subbing out the work would be his best option. “Everyone that really knew these cars is dead. The problem with the Tri-Power is that there are a lot of people who say they can work with them, and really have no idea what they are doing. I sent the assembly to Mike at pontiactripower.com and he did the jetting on it for me – I bolted it on there and it worked like a million bucks,” says Carufel.
The center carburetor on a Tri-Power setup acts as a straight-up two-barrel carburetor, as long as you keep your foot out of the engine you’ll get reasonable fuel mileage. It’s only when the outer two carbs come on line and start dumping fuel into the manifold that the gas-guzzler tax comes into play. As this engine is destined for Carufel’s heavyweight Catalina, the powerband is just right.
The engine makes over 475 lb-ft of torque from 2,900-4,200 rpm and over 300 horsepower from 3,200 rpm on up at Wheeler Dyno Service in Blaine, Minnesota – and will provide perfect motivation for the expected 4,000 pound curb weight of the cruiser.
When the engine was finally on the dyno and making horsepower, “Cole said the last time that engine sounded like that, he had to open the garage door and let the smoke out, as he used to do burnouts with it in the garage just for fun. This engine means a lot to me because it meant a lot to him,” Carufel explains.
“Would I do it again? Absolutely! You cannot buy the education I got from this project. This type of learning only comes from doing.”
This engine is a torque monster, with a flat curve over a wide operating range.