With Rhoads Lifters you can run more cam and still have great low-end torque, engine vacuum and idle quality. The secret? Variable Valve Timing! Rhoads' exclusive patented design reduces lift and duration on the low-end and restores it on the top. This lets you run more camshaft while retaining great low-end streetability, fuel efficiency and better emissions. And they are anti-pump-up for maximum high-end revs. This makes Rhoads lifters ideal for high performance street, marine, strip or oval track.
Rhoads V-Max lifters increase low-end torque and engine vacuum up to 50% more than original Rhoads lifters. They also rev higher, making them ideal for racing classes with vacuum rules. V-Max lifters are fully adjustable and require an adjustable valvetrain.
Typical vacuum increases range between 3 to 5 inches at idle when used with bigger cams. Duration is reduced between 5 and 20 degrees at .050" lift depending on the adjustment. As the rpm increases, so does the lift and duration. Full restoration takes place at approximately 4000 rpm.
611-8178X Instructions (PDF)
It's not uncommon to pick up 2-3" of vacuum under 1500 RPM just by using these lifters. Normally see 25% or more increase in low-end horsepower for performance hydraulic cams.
Lifters bleed down slightly at idle and lower RPM, causing a reduction in valve duration of approximately 10° to 15°, and reducing valve lift .020" to .030" at idle.
Set of 16. All 1955-86 Chevy V8.
Orginal Rhoads Lifters reduce lift and duration at idle by approximately .010" to .020". Duration is reduced by approximately 10 to 15 degrees. Total lift and duration are restored at approximately 3500 rpm. Its not uncommon to pick up 2-3" of vacuum under 1500 RPM just by using these lifters. You will normally also see an increase in low end torque.
Oil viscosity, valve spring pressure and engine temperature all combine to affect the total leak-down of the lifter at idle. Therefore total leak-down is only approximate.
611-9008 Instructions (PDF)
351C, 351M, 400M