by moore1 | Sep 6, 2018 | News |
The primary reason for selecting an aggressive camshaft profile is to bolster the inefficiencies of a cylinder head. The more aggressive the cam profile, the more spring loading is required to keep the lifter in contact with the lobe. Aggressive cam profiles are generally judged unnecessary for use with efficient cylinder heads. For this reason, we favor returning to established profiles because they are less abusive on valve springs. Given an efficient cylinder head, a milder profile camshaft will make just as much horsepower. The proof of this is easily demonstrated by back-to-back dyno testing. Roller lifter failures: Inadequate valve springs are the major cause of roller lifter failures. They enfeeble the valve train, allowing the lifters to be thrown over the nose of the cam lobes, damaging or crushing their needle roller bearings on the impact of landing. If stronger spring loadings are necessary and the durability of the needle rollers is in doubt, use roller lifters with bushings instead of needle bearings. Beehive valve springs: A Beehive valve spring resembles the shape of a whiskey barrel. These springs are frequently used in applications where clearance is at a premium, usually between the underside of the rocker arm and the outer edge of the spring retainer. They are also desirable in the quest for lighter moving parts. The Beehive’s narrow top end adopts a smaller retainer, thus achieves a lighter spring assembly. Beehive springs are commonly used on late-model Ford and LS road-going engines. The LS factory-spec camshaft opens the valves to around 0.530in. Given its stock 1.7:1 rocker ratio, Erson’s aftermarket camshafts with 0.340in...
by moore1 | Sep 4, 2018 | News |
By Archie Bosman: Valve springs have two primary tasks: first, to close the valve after the camshaft opens it and, second, to maintain proper valve clearance, also known as valve lash. Why valve clearance is required for solid tappets (lifters) Valve clearance, or tappet clearance, is the gap between the tip of the valve and the rocker arm when a solid lifter is positioned on the base circle of the camshaft. This clearance accommodates thermal expansion created by engine heat. Metal expansion rates differ between the block, heads, pushrods, valves, etc., and a gap commensurate with the collective expansion is set accordingly. Exhaust valve clearance is often greater than that of the intake valve as it runs hotter and, therefore, grows in length, reducing valve clearance. Unlike solid tappets, hydraulic systems operate with zero clearance. Inadequate clearance As the valve seat wears, the valve moves slightly upward in the cylinder head, reducing valve clearance. If clearance vanishes and the valve does not close fully, compression is lost. Furthermore, escaping hot combustion gasses burn the valve head. Similarly, when combustion occurs on race engines, heat and pressure can distort the valve head, cupping it and pushing the valve upwards through its seat, thus consuming some of its clearance. On overhead cam engines, which have fewer valve train components to absorb deflection during combustion, the effect of lost clearance can be evidenced by a little shock imprint on the camshaft’s base circle caused by the lifter. Excessive clearance In contrast, excessive clearance is detrimental to the entire valve train. As the bigger gap builds momentum, the rocker pounds the valve tip....
by moore1 | Sep 3, 2018 | News |
By Dave Hamer: I joined Benetton in 1988 when they decided to create an R&D department to support their Formula One active suspension ambitions. Both Lotus and Williams had already seized the moment, pushing well ahead with similar programs. Though Benetton was also running an Active test car, they employed a staff of only 80, considerably fewer than the other leading teams. The initial system was developed using various Citroen hydraulic parts, including accumulators and a pressure control valve. The hydraulic power was generated by a Sunstrand gear pump, similar to the high pressure oil pump of a central heating boiler, which Lotus also used at the time. However, these pumps were barely adequate for F1 use; operating at 2,000psi-plus, they required constant attention. The events that led to Benetton’s active suspension and the system’s major components The advent of aerodynamics and particularly ground-effect brought new challenges to suspension design. Ground-effect relied on the car running at a low consistent ride height and, as such, generated huge downforce and cornering power. Notably, spring rates had increased to 3,000lb/in., making the suspension almost solid. Yet due to tyre squash, the car’s ride height still changed with the car’s speed and its mechanical grip was poor. The solution came in the form of new technology known as Active suspension, which replaced the springs and dampers (mostly coil-over-shocks) and anti-roll bars with hydraulic actuators (rams) controlled by a computer. The system employed a pump to provide the pressurised fluid which was piped to a computer-driven valve (a moog servo valve) at each corner of the car. This either directed fluid to the...
by moore1 | Aug 30, 2018 | News |
This two-paragraph brief from engine builder Jon Kaase was uncovered during our research of the more extensive accompanying article on valve springs, valve clearance, bounce, float and surge. Excessive valve spring pressure and its effect on lifters By Alfie Bilk Excessive valve spring pressure is detrimental to power production, as it creates more friction on the lifters. “On my last year’s Edsel EMC contender,” recalls Kaase,” I had single conical springs and noticed the intake adopting a rhythm and floating the valves about 6,000rpm. So, I installed stronger springs and lost 15hp. I speculated the deficiency may involve the intake valves only, and I put the weak springs back on the exhaust, as those valves are smaller and lighter, and the engine picked up 7hp.” Most of the power losses implicated by the use of stronger springs are caused by lifter friction. “The stronger the spring,” he explains, “the harder it is to raise the lifter. Even though you get some of it back when it’s closing, you are pushing it sideways against the lifter bore. This sideways force is called the pressure angle. A flat tappet is less threatened than a roller lifter. In the case of the roller lifter, you impose all kinds of pressure on the sides of the lifter bores. So the more spring pressure you apply the more power it consumes. Cup car teams learned these lessons and, as a matter of course, run light valves and light spring pressures.” To read the about Kaase’s 2017 EMC winning engine click here. Source Kaase Racing Engines, Inc. 735 West Winder...
by moore1 | Aug 7, 2018 | News |
By Freddie Heaney: Donald Campbell’s 300mph record-breaking jet-powered hydroplane, Bluebird K7, has been rebuilt. The vessel was salvaged in March 2001 from the bottom of Lake Coniston, in Cumbria, England, following Campbell’s fatal crash in 1967. It is now readied for testing. Forty-five year-old Campbell died when the 12-year-old watercraft became airborne, back-flipped, crashed and partially disintegrated. Campbell had been travelling at over 300mph in an attempt to break his own 276mph water-speed record. Two months after raising the remains of the Bluebird, in May 2001, Campbell’s body was discovered still wearing his blue nylon overalls. The Bluebird restoration project was undertaken by a team of volunteers from Tyneside in the northeast of England and led by diver and engineer Bill Smith. The restored craft, which has already traveled at 100mph on Loch Fad on the Isle of Bute near Glasgow, Scotland, is currently undergoing tests for water tightness and its ability to withstand wave buffeting. Smith said, “We’ve been 15 years in the rebuild – five years of stripping, cataloging, and cleaning, and ten years since setting the craft’s first rivet. Once these tests are completed, there’s the hope the Bluebird will be showcased at speed back in Cumbria.” The son of British speed record breaker of the 1920s and ‘30s Sir Malcolm Campbell, Donald set eight world speed records in the 1950s and 60s–seven on water and one on land. He remains the only person to accomplish both world land and water speed records in the same year (1964). In 1960 at the Bonneville Salt Flats, he was hospitalized with a fractured skull and burst eardrum...
by moore1 | Jul 11, 2018 | News |
This story languished for a month, at least; materials revealing the timeless technique of racing camshaft development seemed uncomfortably far away. Then Californian Lyle Larson, the accomplished former drag racer, emerged with illuminating experiences from the nineteen sixties and seventies that we feared had been lost. Two weeks later, we found Steve Tanzi near Lake Tahoe with a further treasure trove of material, turning possibility into reality during the 1990s and early years of this century. More recently, Jack McInnis discovered some wonderfully evocative printed materials and photographs that illustrate much of what has long been relevant to hot rodders and motor racers and like-minded persons. By Sam Logan. Five and a half decades ago, in 1963, the shop foreman at Isky Racing Cams in Los Angeles departed to form his own camshaft company. He called it Sig Erson Racing Cams. He orchestrated its agenda, and he led its pursuits until he sold it in 1982. In business, his central aim was inseparbly linked to the tricky concept of keeping his customers and distributors happy. In outdoor activities, Erson was unusually adventurous and in practical terms, particularly in surviving the austerity of desert life, he was unsurpassed. In his youth, there were periods when he lived on the beach by himself and could readily sleep beneath the night skies unperturbed. In Mexico’s austere landscapes, both mountainous and arid, he would embark alone on an entire Baja 1000 pre-race reconnaissance. In spending his nights in the barren wilderness, he was undismayed by the threat of being stranded or perishing on the vast, silent desert soil or alarmed...
Recent Comments