Cams and their relative 'noise'
#21
07-11-2010 | 11:21 PM
Elite HDF Member
Joined: Aug 2006
Posts: 3,863
Likes: 21
From: Kennewick, WA
The length of the pushrod should be the distance between the lifter when resting on the off-lobe position of the cam to the rocker arm with the valve closed ... most grinds for use on street bikes will have the off lobe radius equal to the stock cams ... which is why you can use the stock push rods .... So, the adjustable push rods, when properly adjusted should end up being the same length ....
Potentially any noise might be from the valve train losing momentary contact with each other when the cam opens ... if this is exacerbated due to high lift, the valves can 'float' ... i.e., not close totally ....
R/
'Chop
Potentially any noise might be from the valve train losing momentary contact with each other when the cam opens ... if this is exacerbated due to high lift, the valves can 'float' ... i.e., not close totally ....
R/
'Chop
Some of the noise comes from the lobe shape. I was reading that there is one manufacturer that has revised the heal of the lobe to cut down on valve chatter. Think of it this way, you're on top of a hill going down. One hill is gradual and an un-eventful decent. The other is steep with a very pronounced break at the top. As speed increases you catch a little air on the steep hill but not on the gradual hill.
It's all a compromise, the longer the valve stays at maximum lift the more radical the heal of the lobe will be and that increases the noise.
I could be way off base here, it's just what I have interpreted from some reading I have done.
#22
07-12-2010 | 11:32 PM
6th Gear
Joined: Sep 2007
Posts: 11
Likes: 0
From:
07 SuperGlide
Wood TW6-6's, V&H slipons,
Power Commander, dyno tuned
Last edited by ioncat14; 07-12-2010 at 11:34 PM.
#24
07-13-2010 | 09:19 AM
Grand HDF Member
Joined: May 2007
Posts: 3,852
Likes: 476
From: Alberta
What dealer are you going to? Naturally, they're gonna push the HD stuff but some have more experience with hop-ups using "other" products...I'm using HQ cams in my motor with their lifters and SE perfect fit pushrods to make up for the HQ heads. Have over 30k miles on the build, two-up and solo; still running strong...the gear drive/cam lobes may be noisier but so is the exhaust and you can tell it's NOT a stock HD when it's idleing.
#25
07-14-2010 | 07:05 PM
Road Captain
Joined: Aug 2009
Posts: 619
Likes: 3
From: In Garage
I wonder if the guys who change there valve springs are experiencing any noise??
adjustable pushrods are heavier too. So its going to take more spring pressure to controll the valve train. so not only does the spring have to lift the valve, locks and keepers. It also hase to push the rocker arms, pushrod, and hifters, with there related drag(friction). In other words there is more chance of chatter.
adjustable pushrods are heavier too. So its going to take more spring pressure to controll the valve train. so not only does the spring have to lift the valve, locks and keepers. It also hase to push the rocker arms, pushrod, and hifters, with there related drag(friction). In other words there is more chance of chatter.
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