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Discussion Starter · #1 ·
I’m not well versed in the mechanics of engines so bare with me if I have some of this wrong in asking my question. I want to understand what the value or advantage of the adjustable pushrod is, as compared to the fixed rod. As I se it, in the 883/1200 engine the crank shaft lobe moves the tappet up and down, on which the pushrod sits. The other end of the pushrod rides in the valve rocker arm and actuates the valve. The tappet/roller assembly has a feature where as it takes on amounts of oil to "pump up" the assembly and to remove any slack tolerance in the transfer of motion up the chain to the valve. If the tappet assembly removes the "play", what benefit is the adjustable feature on a pushrod?
 

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You don't have to pull heads for some work. I had a head off this summer. Little wet around o-ring. If I had adjusable I could have checked and reseated o-ring. I wouldn't put them in until engine open for another reason. Doubt you will notice much of performance gain. With certain builds you may have to adjust.

They make fixed pushrods too, lighter, if you really know what you want for a build. Don't know anybody who runs them. But I am sure people do.
 

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As mentioned adjustable pushrods can allow you to swap cams without taking the heads off. Also certain lifters require adjustable pushrods. Combinations of head gasket thickness and head milling could also lead to the use of adjustable pushrods. Lifters require a certain amount of cushion to be set properly. Adjustable pushrods can allow you to meet those requirements for different combinations of alterations. On a stock bike with no mods there would be no dvantage that I can think of.
 

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geoffreyt said:
I’m not well versed in the mechanics of engines so bare with me if I have some of this wrong in asking my question. I want to understand what the value or advantage of the adjustable pushrod is, as compared to the fixed rod. As I se it, in the 883/1200 engine the crank shaft lobe moves the tappet up and down, on which the pushrod sits. The other end of the pushrod rides in the valve rocker arm and actuates the valve. The tappet/roller assembly has a feature where as it takes on amounts of oil to "pump up" the assembly and to remove any slack tolerance in the transfer of motion up the chain to the valve. If the tappet assembly removes the "play", what benefit is the adjustable feature on a pushrod?

Basically what the other posters said, it makes it easier and less expensive the second time you have to open the cam chest. In years past, Harley always used either adjustable tappets (flatheads, Knuckleheads, etc.) or adjustable pushrods as in the shovelhead. It made things a lot easier, especially if you don't want to disturb the heads. Those upper level gaskets aren't cheap.

They got away from that in the Evoution era and now the TC's. They just use precision cut pushrods which are fine if you don't want to fool with them.
 

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Discussion Starter · #5 ·
The reason I ask is Im getting ready to have the Zipper's Torkster kit put in my 883. I happen to live close to Zippers so I stopped in one day and the guy I was talking to suggested I have adjustable pushrods put in also, along with a Zippers programable ignition. His pitch was if you want close tollerances, that is no slop, for performance then you will want these adjustable rods. http://www.zippersperformance.com/catalogue/showproduct.asp?cat=865&prod=2062
 

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hotshotfxdl said:
As mentioned adjustable pushrods can allow you to swap cams without taking the heads off. Also certain lifters require adjustable pushrods. Combinations of head gasket thickness and head milling could also lead to the use of adjustable pushrods. Lifters require a certain amount of cushion to be set properly. Adjustable pushrods can allow you to meet those requirements for different combinations of alterations. On a stock bike with no mods there would be no dvantage that I can think of.
How does a lifter know if a solid or adjustable pushrod is being used? Adjustable pushrods are good if you can't make up your mind on which cam you need or if you use a chain drive cam assembly.
 

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ccrane2299 said:
"lighter is faster - Colin Chapman (founder of Lotus)"

Adjustables are heavier.....
And heavier means lower revs and less power. Start asking the weight of the parts you are looking at and what the stock parts weighs. www.revperf.com has some new (and I believe lighter) lifters. WITH a lifetime warranty!!!!
 

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