Reply to "Head/Manifold Choices for 351C-2V?"

Your rear wheel horsepower goals equate to 470 to 500 crank horsepower. My advice is to not set a horsepower goal, rather build the engine for a certain type of power characteristic, and let the numbers fall where they may. I'm of course infamous for my appreciation of the 4V cylinder heads. If you build the engine right you can rely on it to accelerate the car like nobody's business, by virtue of the kind of power delivery it will have equipped with 4V heads.

Keep in mind that 500+ bhp was the horsepower output of this motor in endurance racing tune 40 years ago. Cleveland race engines normally made peak horsepower at 7000 rpm (or higher). You desire to reach this same output at lower rpm, in street tune. This is possible due to progress made in camshaft/valve train technology. You cannot achieve 470 to 500 bhp with a 40 year old Boss cam (as you mentioned above). Those 40 year old 500 horsepower race cams had very long duration lobes, which was a necessity to open the valves 0.600". Long duration cam lobes are always accompanied by lots of overlap, which ruins drivability. It was possible to make 400 horsepower 40 years ago with a hydraulic tappet cam and still have good drivability (about 0.500" lift and 60° overlap). 400 horsepower in a street car was a lot of horsepower! There were 450 horsepower solid tappet street cams, which gave-up quite a bit of low rpm drivability to achieve that extra 50 bhp (about 0.540" net lift and 70° overlap). Utilizing modern lobes will make it easier to achieve your power goals while not having to compromise drivability or low rpm performance. Actuate the valves with a modern cam having about 228° intake duration (at 0.050) and net valve lift of 0.600" or more, BUT less than 2° overlap at 0.050 (less than 62° overlap based on advertised duration). The exhaust valve should open around 80° BBDC and the intake valve should close around 70° ABDC. No less than 112° LSA.

The better the induction and exhaust systems are the easier your power goal will be to achieve. At your power goal the 4V heads would need porting. They don't need much porting, pocket clean-up and 3 angle valve seats are the biggest improvements. The important thing is to avoid screwing-up the performance of the heads as many porters do, so its nice if you can find a head porter who knows what they're doing in regards to those heads. The best "carbureted" induction would be the Aussie Speed manifold and Weber IDF carbs. If your preference is a single 4 barrel carb, then choose the Blue Thunder manifold and a 750 or 850 carb with annular booster venturis. You can achieve a higher peak number with a single plain manifold, but the Blue Thunder manifold will make more bhp across the rpm range where the engine shall operate 99% of the time. On the exhaust side choose headers with 1-7/8" or 2" primaries, and a proper collector. Set-up the engine for 91 octane fuel with 7.7:1 or 7.8:1 dynamic compression. Complement the engine with 3.89:1 gears (assuming a 26" rear tire), traction lock, and Shelby/Traction Master traction bars.

In terms of aftermarket heads, there are several choices in high port racing heads which will make big power numbers if you want to go that route. They are limited in intake manifold compatibility, and in most instances the carb will sit so high it may not fit beneath the engine compartment hood. Race heads would probably require custom headers for the Cougar as well. The first aluminum Ford race head, the A3 head, had a dedicated intake manifold based on the Edelbrock Torker, that would probably fit under the hood. The SCM dual plane manifold will probably mate with those heads too, it mounts the carb even lower than the Torker.

Moving on to street heads with standard height intake ports the SCM heads are a great choice, they are modern iterations of the iron 4V heads in many ways. The intake ports are about the same cross-sectional area (tuned for the same rpm as the 4V heads) but they lack the big inlet and ramp that the 4V intake ports have, therefore the intake port "shape" is much more consistent. The valve pockets are very modern (generous in size). The CNC intake ports flow "out of the box" about as well as professionally hand ported 4V ports. That's quite an achievement considering the SCM ports do not have the ramp built into them. Darin Morgan is also very proud of the exhaust port he designed for those heads. Replacing unported 4V heads with a set of SCM heads will net a 70 bhp increase in horsepower. Some of that is due to the fact the SCM heads are CNC ported out of the box, some of that is due to the improved exhaust port, and some of that is due to the Westlake/Yates style (high swirl) combustion chamber. Manifold choices are limited for heads with "stuffed" 4V ports, so that is something to consider, depending upon what your induction preference is. In terms of a dual plane manifold, the SCM manifold is the only choice ... but its a well designed choice. All aftermarket heads have smaller exhaust valves than the 4V heads, and work better with headers having 1-3/4" primaries.

I'll tell you why I like recommending these heads. First, they are designed by a gentleman who is at the top in his profession, Darin Morgan. Second, they are cast and manufactured in Australia, not China. Third, I have confidence you'll have no regrets doing business with Scott Cook. He's a good guy.

In terms of 2V heads, or domestically manufactured heads, the CNC ported Trick Flow heads are the way to go. There's lots of good feedback regarding their performance.