Re: 1967 427/435 Cam and Lifters
I don't think anyone answered this question, so here it is.
The damper is a wound piece of "flat wire" inside the spring. OE SB springs of the era are this design. The damper coil is an interference fit inside the spring (but has a very low rate - insignificant, in fact, because you can compress them with your fingers), so it creates friction i.e. it acts like a damper - like a resistor in an electrical circuit.
The purpose of the damper is to mitigate "spring surge". At very high frequencies a spring can develop a standing wave. If severe enough it can cause coil bind and break the spring. The interference fit flat wire damper is a very effective and inexpensive way to get better high rev performance out of a simple, single valve spring.
There are high speed video clips on the Web showing mild spring surge. You see the spring open and close, but after closing there is a small wave that goes back up the spring. it's damped out prior to the next open cycle, so no problem. If it didn't damp out prior to the next opening cycle there's a possiblity that the spring could break due to coil bind when the valve is being opened and the standing wave is moving up the spring.
Dual or triple valve springs usually don't have dampers as above, because having multiple springs of different rates provides a good degree of damping without introducing extra friction.
The single spring/damper works very well on OE SBs, but serious high revving racing SBs are usually set up with multiple springs. The design didn't work out well on BBs, so GM finally went to the second design dual spring, but it took them a good five years to fix the problem with the early single spring/damper design.
Duke
I don't think anyone answered this question, so here it is.
The damper is a wound piece of "flat wire" inside the spring. OE SB springs of the era are this design. The damper coil is an interference fit inside the spring (but has a very low rate - insignificant, in fact, because you can compress them with your fingers), so it creates friction i.e. it acts like a damper - like a resistor in an electrical circuit.
The purpose of the damper is to mitigate "spring surge". At very high frequencies a spring can develop a standing wave. If severe enough it can cause coil bind and break the spring. The interference fit flat wire damper is a very effective and inexpensive way to get better high rev performance out of a simple, single valve spring.
There are high speed video clips on the Web showing mild spring surge. You see the spring open and close, but after closing there is a small wave that goes back up the spring. it's damped out prior to the next open cycle, so no problem. If it didn't damp out prior to the next opening cycle there's a possiblity that the spring could break due to coil bind when the valve is being opened and the standing wave is moving up the spring.
Dual or triple valve springs usually don't have dampers as above, because having multiple springs of different rates provides a good degree of damping without introducing extra friction.
The single spring/damper works very well on OE SBs, but serious high revving racing SBs are usually set up with multiple springs. The design didn't work out well on BBs, so GM finally went to the second design dual spring, but it took them a good five years to fix the problem with the early single spring/damper design.
Duke
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