general question - single cam vs twin cam

Normally twin cams are used with 4-valve heads, 2 Intake & 2 Exhaust valves per cylinder. This allows for much smaller valves, springs & retainers which means much lighter valvetrain that is more stable at Hi RPMs = Higher RPM capability.

KoTT said:

what is the difference? why would you want two camshafts in a car?

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Mostly cost, weight and space. Dual over head cams do offer some tunability in that one or both cams can be advanced or retarded by speed sensitive mechanisms which essentially results in a variable Lobe Separation Angle (LSA). This is mostly useful on smallish engines typical of the Euros and Japanese of years past where varying the LSA can be used to recover some bottom end torque at one extreme and add some top end horsepower at the other.

Frankly, back when I had a 1987 Alfa Spider Veloce, I found it far more effective to take the variable timing, twin cam, 4 banger out and put a 5 liter small block Ford in. Not quite as easy a swap as I make it sound, but well worth the effort.

Bogie

Can you imagine the lobe count on a 4 valve system V-engine? I think it would br virtualy imposible. One thing about overhead cams though, They eliminate valve lifters and are quick to change.

sqzbox said:

Can you imagine the lobe count on a 4 valve system V-engine? I think it would br virtualy imposible. One thing about overhead cams though, They eliminate valve lifters and are quick to change.

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you mena like a Ford mod motor? Or the Northstar?