Just because Fords are the minority in almost every racing class, doesn't mean the engines
NASCAR has just accepted a raised-port, canted-valve head for the Nextel Cup guys, but we've been racing a version of that in Dirt Late Models for some time now. We are starting our third year with canted-valve heads on Ford engines, and they have definite advantages. We are lucky in Late Model dirt racing where the rules are not very restrictive and we have the freedom to do what we want.
Canted-valve heads aren't a major power gain for the engines in the bottom and middle rpm ranges, but they do run quite a bit harder up high. The reason for this is quite simple: The canted-valve design angles the valves away from the cylinder walls, which improves flow at high-valve lift. This doesn't make much difference at lower rpm levels because the slower engine speed allows enough time to completely fill the combustion chamber. When you get above 8,000 rpm, conventional heads start having difficulty filling the chambers. The canted valves reduce shrouding against the chamber walls and improve flow in the upper rpm ranges.
You can't see any difference between canted-valve heads and conventional heads until you get the motor revved up above 8,000 rpm, and the higher you get above that, the better the head gets. If you look at a 410ci motor, at 8,500 rpm, the canted-valve head offers a pretty significant gain. It improves the power by approximately 25 hp. But if you compare the heads on the same 410 engine at 7,000 rpm, it's minimal. The canted-valve head is only starting to come on at that point.
If you're looking into running these heads, the biggest concern is added weight in the valvetrain. The valves are angled into the combustion chamber, which means the stems are longer. Try to make things as light as you can, and also run a cam profile that you know will allow the engine to rev up. Still, the extra weight of the valves means you have to be careful to keep everything in control. We put the entire valvetrain package on a spin fixture and run it up so that we know at what rpm there will be trouble with a certain configuration. Smart decisions are a must when it comes to lobe design.Larry ClarkCustom Race Engines865/573-1449
Oil Showers They aren't specific to Fords, but valve cover oilers are a good idea anytime you're pushing an engine to its limits. The oilers are spray bars in the valve covers that spray a mist of oil onto the rocker arms and valvesprings. This helps reduce friction and keeps the valvesprings cooler. Heat in the springs is a big contributor to spring failure, and the oil really helps this matter. Normally, valve cover oilers are used with dry-sump engines, which also makes them easy to plumb. With a dry-sump, you just use a tee fitting from an oil supply line and feed it into the inlet on the valve cover. After the oil sprays on to the valvesprings and rocker arms, it drains back to the pickups via the normal path. You need more oil volume and will perhaps need to spin your oil pump a little faster to keep up with the added demand.Don LositoUltra Pro Machine704/392-9955
If you are running a flat-tappet cam, the Ford block has a definite advantage over Chevrolet. Ford's lifter bores are 0.875 inch. With a flat-tappet cam, the bigger the lifter, the greater the velocity it can withstand before the sides start digging into the lobe of the camshaft. On a stock Chevrolet with a flat tappet, you are limited to a velocity of about 0.007 inch per degree of rotation. Because a Ford's lifter bore is larger, you can get to almost 0.0075 in terms of lift velocity. That extra velocity means you can open the valves in the combustion chamber that much quicker. A lot of dirt racing series require you to run stock lifter bores, so in a Ford, this can be a real advantage.Billy GodboldCompetition Cams800/999-0853www.compcams.com