| zorrro |
Sun Mar 06, 2022 9:41 pm |
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Where do I want to have my valve adjustment screw when I set up my rocker geometry? If I set it all The way backed out, I’ll have no adjustment in the future. If I have the screws all the way down, the adjustment screws stick out like buck teeth and look weak. If I put them in The middle, I’m still only getting 1/2 the adjustment range over life of motor. Thanks much!…Z
Specs:
GB elephant foot adjusters.
Stock rockers machined and slightly counter bored to accommodate elephant feet.
W-100 cam
Solid shafts
Single HD springs.
69x90.5 with decked case.
Shimmed up enough for 7.75:1 CR. |
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| clonebug |
Sun Mar 06, 2022 10:11 pm |
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If they are the stock rockers turn the screw out 1.5 turns from all the way in and do your geometry from that.
You will probably have to get shorter push rods.
I ran swivel feet and shimmed the rocker shaft out .130" and used the stock pushrods. I put over 20,000 miles on them that way and they never gave issues or had any abnormal wear.
The cam and lifters had 46,000 miles on them and were still in perfect shape after a couple different non samba setups.
If you back cut the rockers far enough, you might be able to do the same...YMMV |
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| gorbur |
Thu Apr 03, 2025 10:44 am |
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I'm trying to understand the position of the swivel foot adjuster while setting up the geometry. The rockers are CB1684 (Super Stock 1.1:1) and the valve side ground down .07" and slightly chamfered.
For the geometry setup the adjuster was 1.5 turns out from bottoming the swivel foot (Pic 1). At that it could easily swivel without hitting the rocker. I ended up with a .057" shim under the pads giving me what I think is good PR, valve axis alignment and somewhat centred on the valve tip. Pushrods then ended up being slightly shorter than stock.
My understanding is that I want to have the ball of the swivel foot as close to the rocker as possible without binding. And I believe that minimizes the sweep.
My question becomes does the 1 to 1.5 turns allow me enough adjustment room in the futiure?. I assume it will as compensating for wear would have me moving the adjuster out more ie. > 1.5 turns
Pic 1 (1.5 turns from bottoming out)
Pic 2 (somwhat centred)
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| Brian_e |
Thu Apr 03, 2025 11:20 am |
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The number of turns in or out is irrelevant. There is no set number, you just do whatever it takes to get the geometry correct. No two engines will be the same.
The goal is to get the adjuster shank to be in line with the valve stem at half lift, BUT also equal angles at full, and no lift. Stacking shims under the rocker stands is rarely needed. Getting the rocker arm shaft center line perpendicular to the valve tip at half lift will usually give you the least amount of swipe, and also the closest to equal angles at full and no lift.
Brian |
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| gorbur |
Thu Apr 03, 2025 12:00 pm |
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Thanks Brian,
Understood. As it is now I have the angle from no lift to 1/2 lift equal to 1/2 lift to full lift. And at 1/2 lift the adjuster parallel to the valve stem axis and push rod to centre of rocker shaft at an 90 angle.
Pretty sure i could shave another .03" off the underside (.1 total) and get the same geometry with no shim. My concern there was if I do that and extend the chamfer I'll only be a thread or two from the oiling hole. Just not sure if that would be an issue or not.
On my original question tho, Is it correct to assume that once set up I'll only be adjusting for wear by turning the adjuster in more? |
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