Does your engine run like a dream or a nightmare?
Achieving that classic muscle car rumble under the hood is what most of us are after, but too much of a good thing can be make an engine a nightmare to tune. With a very wild camshaft profile the engine cant complete the entire combustion process so with the valves are still open, this causes a backfire effect into the intake runners which doesn’t necessarily create more power. Engines need at least 14-15lbs. vacuum to run power brakes, with todays more efficient hydraulic roller camshafts this is achievable to make great torque. Good idle quality and crisp throttle response. Whenever youre at the fence with a choice between a smaller or larger camshaft we recommended always going tamer
especially for a cruiser. Engine Factory has a selection of camshafts that are setup with matching components Cylinder heads, compression, pistons, induction and the list goes on. Having the right amount of lope but still have ample vacuum to run accessories is the ideal situation.
Vacuum and idle characteristics of an engine:
“SMOOTH” idle is as smooth or almost as smooth as a stock OEM engine and has high manifold vacuum, 18 inches and higher. These engines work well the stock exhaust system and torque converter but all engines benefit from good headers and performance mufflers.
“MILD” idle has a little rumble and has very good manifold vacuum, 16 inches and higher. These engines also work nicely with the stock exhaust system and torque converter.
“LOPEY” idle is a well defined lope as in the lope or gallop of a horse, and will have good manifold vacuum, 14 inches and higher.This is pretty much the “Muscle Car” idle of most cars of the 1960’s and 1970’s. This is the largest cam recommended for the stock torque convertor.
“CHOPPY” idle is a very noticeable performance idle and will have a somewhat lower manifold vacuum, 9 to 12 inches. These engines need headers and a torque converter in the 2400 to 2800 RPM range. This is basically a rougher “Muscle Car” idle.
“ROUGH” or “RADICAL” idle is rougher than “Choppy” and is tolerated by performance type people, however most people are happier with the Lopey or Choppy idle type camshafts. With the “Rough” idle cam, the vacuum will be under 8″. Also this engine will need headers and performance exhaust system. A 2800 RPM or higher torque converter is recommended. A vacuum canister or electric vacuum pump may be necessary.
Generally speaking Engine Factory provides engines in the Mild to Choppy Idle Range. These engines can be used for everyday to Show n Go Vehicles.
