Reply to "what cam - lifters and rockers"

Well I'll give my usual spiel regarding balanced performance. Street tires are a limiting factor to going fast, they can only apply so much power to the ground, at a certain rate, without loosing adhesion. I assume your car will not be aided by "traction control" as modern cars with high-output engines are. So a wide flat torque curve is better than a narrow "peaky" torque curve for a few reasons, one of those reasons being because its easier to control traction.

A good traction system (traction bars) will help the effort. The lightest rear wheel/rear tire package you can find (or afford) will also help the car accelerate faster, as do other lightened drive train parts such as axles and the driveshaft (aluminum).

Back in the 1960s, Ford's racing engineers believed a wide flat torque curve was advantageous for endurance racing, circuit racing, road racing, what ever name you want to give to that type of racing. Ford had some expertise in those regards, seeing how they had won every championship they had set their goal to winning. The canted valve cylinder head design was chosen specifically because testing proved it was the superior design for making wide-flat torque curves. So it should come as no surprise the 351C 4V cylinder head excels at making power characterized by wide flat torque curves.

The 351C 4V cylinder heads want to make peak horsepower around 6000 rpm, so lots of duration is not needed if peak horsepower at that rpm is your goal. If you want to push the power band higher than that, then we need to start stretching the camshaft duration figures to accomplish that, but long duration also means more overlap, and that's something I advise you to steer clear of. There's three ideas I'd like to emphasize here: (1) The camshaft is not the dominant contributor to a 351C 4V street engine's power band and horsepower output, the 4V cylinder heads are. In regards to selecting a camshaft the most important thing shall be to select one which avoids the common cam timing mistakes, and which lifts the valves "high" to take advantage of the 4V head's volumetric efficiency. (2) Going fast at a stop light doesn't mean having a high peak horsepower number, it means having a power band that pulls hard from low-rpm (just above idle) and continues to pull hard to 6000 rpm or higher. (3) Trust the 351C equipped with 4V heads to do its job, nothing accelerates quite as hard as a well running 351C 4V. I learned to trust this engine's abilities in the late 1970s, but I am still amazed by those abilities today. I may be old fashioned, but I prefer to focus on going fast, and not on having a high number on a dyno sheet. Build the engine to have a certain power characteristic, use the best parts, and let the dyno numbers fall where they will.

Every way in which you can improve the combustion process and make the induction system more efficient will reduce how "big" the camshaft must be in order to make "big" horsepower. 500 to 570 horsepower was pro-level horsepower for any size engine when the 351C was designed. In those days valves lifted off their seats by 0.600" was also state of the art for a pro-level endurance racing engine. Although that's standard valve lift for a modern hydraulic roller cam (like the cam in the LS7 Corvette engine) in the early 1970s solid flat tappet racing cams having 0.600" valve lift were very long duration - high overlap camshafts which pushed the limits in race engine performance and reliability. The improved specification of modern camshafts was achieved via advancements in successive generations of camshaft grinding machinery and it was made usable by advancements in valve spring technology.

Assuming the car is set-up to operate on 91 octane North American fuel, I'd recommend setting the dynamic compression ratio at about 7.6:1 or 7.7:1. If you're planning a single four barrel carb induction system the Blue Thunder manifold compliments the 4V heads well, and operates over a wide power band. It gives the engine a good kick in the mid-range power. The carburetor will be in the 750 cfm to 850 cfm range, and annular booster venturis will help the effort. Fuel injection, even throttle body injection, will improve low rpm performance quite a bit (~15%) in comparison to a carburetor. If you're having to make custom headers, consider using a tri-Y design for another kick in mid-range power. Try also to build or buy headers in which the primaries exit the heads straight out of the ports, rather than abruptly bending downward. You may also consider having some minor work performed on the heads ... pocket clean-up and 3 angle valve seats, plus a little work in the roof and sides of the exhaust port. Its hard to give guidance regarding selection of a business to port 4V cylinder heads in broad terms. Do not agree to extreme porting of the 4V heads unless the business has a decades old reputation for porting 351C 4V cylinder heads; such as Koontz and Company (Arkadelphia Arkansas) or Valley Head Service (Northridge California). Most "cylinder head porting businesses" do not understand the 4V heads. I've seen 351C 4V performance worsened by many businesses claiming to be professionals at cylinder head porting. It is a healthy thing to feel uneasy about handing over your 4V cylinder heads to any business for modification. A simple amount of pocket and port clean-up combined with 3 angle valve seats will increase air flow through both the intake and exhaust ports by 50 cfm at 0.600" valve lift. Cleaned up in that manner the 351C 4V cylinder head air flow performance is similar to the air flow performance of the CNC ported LS7 cylinder heads ... not bad considering the 351C heads were cast 40 years earlier than the LS7 heads.

Camshaft-wise, I think a cam with 112° LSA is in order, or since this is a weekend warrior, perhaps even 110° LSA, but no less than that. Keep in mind that 110° to 112° LSA in a 351C 4V is like 106° to 108° LSA in an in-line valve motor. This is because the big canted valves increase the interaction between the exhaust port, combustion chamber, piston motion, and intake port during the overlap period. I like the idea of 112° lsa to compliment the wide-flat power band of the other engine parts. This will also net more low rpm power and better vacuum at idle. I suppose everyone expects me to pull some "special" set of lobes from the Bullet Cams website. If drivability was more of a concern I'd probably go that route, but the Crane hydraulic roller cam HR-224 is in the ball park ... considering the weekend warrior application of this engine.

286°/294° advertised duration (290° average duration)
224°/232° duration at 0.050" (228° average duration)
0.586"/0.609" valve lift
Exhaust valve opens at 80° BBDC (53° BBDC @ 0.050")
66° overlap (4° overlap @ 0.050")
Intake valve closes at 74° ABDC (39° ABDC @ 0.050")

I like this cam better than Crane's HR-228 cam because overlap is a bit less. Looking strictly at advertised duration the valve event timing of the HR-224 cam looks like it could stand to be advanced 2°. But the Crane camshaft employs asymmetric lobes, so taking valve event timing at 0.050" lift into consideration ... the cam timing looks good as-is. Its a little bit more cam than I'd want in my car, more cam than what is prudent for a daily driver, but it should suit the weekend warrior plans you have for your car. Use Crane's hydraulic roller tappets, and put their steel gear on the engine's distributor.

The large and heavy 351C 4V intake valve, the high ratio (1.73:1) rocker arm, and the canted valve geometry which splays the pushrods apart at extreme angles, constitutes one of the toughest valve train applications of any OHV engine. Since you are dramatically increasing valve lift, you have to assume you can not take any short-cuts in the quality of the valve train componentry you select. Keep in mind your engine's modern valve train shall be lifting the valves off the seats as much as racing cams did 40 years ago, with less camshaft lobe duration, and with hydraulic tappets rather than solid tappets!

Since you're planning on installing tappet bore bushings, you don't need to concern yourself with limiting oil to the valve train via the push rods. So select a nice set of 3/8" OD push rods, manufactured using 0.080" wall thickness seamless chromoly tubing. Some folks like beehive springs, some have had problems with them. Be aware there are "inexpensive" beehive springs on the market, and avoid them. Use the gold colored beehive springs from PAC racing springs, or don't use beehive springs at all. Pay special attention to the installed height of the beehive springs, because they are not installed at the same height as standard 351C springs. Whatever valve springs you decide upon, they should provide about 150 pounds seated force, and about 370 pounds over the nose for this hydraulic roller cam valve train. Its helpful to lighten the intake valve, but that doesn't necessarily mean using titanium valves. A lightened stainless intake valve like the Manley Race Master valve, combined with titanium retainers for the intake valve springs, is a smart combination. There's nothing to be gained in lightening the exhaust valve unless the intake valve is lighter. Set the valve train up so that the intake valves float first (because its floating exhaust valves that hit pistons).

For rocker arms I wouldn't use anything but "shaft mount" style rocker arms myself, the Yella Terra YT6321 rockers or the T&D Machine #7200 rockers. Be forewarned they are pricier than other alternatives. I accept the extra expense for several reasons. They allow you to set-up rocker geometry with the heads on the bench. This is simply a better way to do things than the push rod length verses fulcrum height method. Tappet compression (similar to lash adjustment) is accomplished with a pushrod cup adjuster. There's no cutting & welding of guide plates to get rocker tips to align with valve tips, there's no push rods rubbing on guide plates, the possibility of rock-arm induced valve train stability issues is essentially nullified in a street application. The HR-224 cam complimented with T&D 1.8:1 ratio rocker arms for the intake valves would give you an induction system with 0.610" intake valve lift. The T&D 1.7:1 rockers would be fine for the exhaust valves (exhaust valve lift would thus be reduced to 0.598").

Get the ignition & carburetor (fuel injection?) dialed-in ... and rock n roll. When the guys with the Z06 pull up next to you at a stop light, they'll be in for a spanking from a 40 year old charging rhino.