Comp 918 springs with XR265 cam.. valvetrain noise
10-02-2008, 11:09 AM
#21
After playing with my 4.8L on the engine stand, I grabbed a rocker that's at full rest and it wiggles from side to side. It clicks as there is side to side play from the needle bearings (naturally there has to be). I would think the 918's over the LS6 springs have a considerably higher amount of seat pressure at rest. This in fact is putting more stress on the rocker so you are going to hear that clack or side to side movement as the rocker leaves and returns back to its resting position. I believe it to be the nature of the beast. Maybe this is moreso heard than the initial theory I had of the valves slamming onto their seats.
EDIT - my noise may be lifter related though? Either way, it's been noisy like that for 13k, so as you mentioned it's just the nature of the beast.
10-02-2008, 11:22 AM
#22
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The 918's are 130# at rest and the LS6 springs are 90# at rest. They get closer as they compress, but less at rest. GM probably wanted them that way to quiet them down.
The 915's have almost the same spec's as the LS6 springs. I'd guess they'd make about the same amount of noise.
The 915's have almost the same spec's as the LS6 springs. I'd guess they'd make about the same amount of noise.
10-02-2008, 12:37 PM
#23
The 918's are 130# at rest and the LS6 springs are 90# at rest. They get closer as they compress, but less at rest. GM probably wanted them that way to quiet them down.
The 915's have almost the same spec's as the LS6 springs. I'd guess they'd make about the same amount of noise.
The 915's have almost the same spec's as the LS6 springs. I'd guess they'd make about the same amount of noise.
10-04-2008, 10:50 AM
#24
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so i take it even if i change out the pushrods for slightly longer ones, there's no way of getting rid of this sewing machine of an engine, unless i change the springs out to something like the 915s?
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