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JayP Samba Member
Joined: September 03, 2007 Posts: 34
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Posted: Mon Jun 14, 2021 6:10 pm Post subject: Scat 1.4 rockers geometry help |
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Hi everyone, I have searched the forum for geometry topics that match my issue but I cannot find any. A little background on my “occasional” street motor build: it is a 82x94 with a Web 86C cam, 043 Mexican casting heads with stock length valves and CB 650 springs. The problem I am having is I can’t seem to get both the swipe pattern on the lash cap and the pushrod/adjuster lined up at the same time. My swipe pattern was too high so I had to lower the rocker pedestals. For a very good pushrod/adjuster alignment, I need to lower the pedestals another .050” (the alignment is right .050” short of half lift) for a total of .200”. The problem you see in the photo is the rocker at zero lift is way too low on the lash cap, which will only worsen if I lower the rockers more. The entire swipe pattern is low. I added a .060” shim under the rockers which gives a better just below/center/just above swipe pattern but you can see in the next photo that the pushrod alignment is way off. I am looking for help as to my options. Do these rockers, which are the Pro Comps, need drastic changes like moving the rocker studs higher, etc? Any guidance will be appreciated.
JayP
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Mon Jun 14, 2021 6:31 pm Post subject: Re: Scat 1.4 rockers geometry help |
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Get your swipe pattern right and don’t worry about the pushrod alignment. |
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Clatter Samba Member
Joined: September 24, 2003 Posts: 7527 Location: Santa Cruz
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Posted: Wed Jun 16, 2021 3:42 pm Post subject: Re: Scat 1.4 rockers geometry help |
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txoval wrote: |
Get your swipe pattern right and don’t worry about the pushrod alignment. |
I was taught the opposite, but agree with you for different reasons.
If you're going to deviate from exactly 90 degrees (pushrod straight to adjuster) at half lift,
Do so towards the 'higher lift' side not the 'lower lift' side.
Said another way,
Some like their rocker geometry so that the 90 angle comes -after- half-lift.
You want that ideal right-angle coming with more spring pressure - towards full lift, when it matters more, rather than towards zero lift, when the spring pressure is less..
Makes sense? Hopefully?
There's also the notion that your ideal geometry would be the one that produces the most overall lift at the valve.
But that's another ism of valvetrain geometry,
Of which there are plenty.. _________________ Bus Motor Build
What’s That Noise?!? |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Wed Jun 16, 2021 5:15 pm Post subject: Re: Scat 1.4 rockers geometry help |
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Can you post a picture looking at the head from the side, so we can see all four valves? |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Wed Jun 16, 2021 6:33 pm Post subject: Re: Scat 1.4 rockers geometry help |
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After reading what your wrote again, you definitely have an issue with the stud placement.
What is odd is that its usually the opposite...where the studs are too close to the valve |
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JayP Samba Member
Joined: September 03, 2007 Posts: 34
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Posted: Wed Jun 16, 2021 10:50 pm Post subject: Re: Scat 1.4 rockers geometry help |
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Thank you both for the responses, I understand what you both are saying. I too was taught the pushrod/adjuster alignment was important. So acting like a taller lash cap, I added a .050" small washer on top of the lash cap to act as if I cut the pedestals .050". At 1/2 lift the alignment looks real good but again, the swipe pattern is a bit lower than center, although not by much. The angle of the pushrod/adjuster at both zero and full lift look pretty even. But the swipe starts out low on the cap and I get just below center at half lift and just a hair above center at full lift. There does not seem to be a way to get both the swipe and the pushrod where they need to be by shimming, lowering the rockers, etc. I wonder if Scat offers an offset shaft?
txoval, I am not sure what angle you want to see. By side do you mean take the photo from above the valves or like the photo above but include all the valves?
JayP |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Thu Jun 17, 2021 4:10 am Post subject: Re: Scat 1.4 rockers geometry help |
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From above the valves.
Also, take photos of your current mock-up at 0, half, and full from the side like above.
You say your pushrod angle is the same at 0 and full, but I hope you mean the same angle, but opposite directions. With this setup, what’s your swipe? Slightly below at 0? If so, I’d say it’s good, but your picture above is not slightly below, it’s at the bottom tip |
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Ohio Tom Samba Member
Joined: February 09, 2006 Posts: 1657 Location: Marshallville Ohio
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Posted: Thu Jun 17, 2021 6:11 am Post subject: Re: Scat 1.4 rockers geometry help |
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go by the swipe pattern on the lash cap.
don't worry about the adjuster. It's a ball-socket setup. It doesn't care.
Been using Scat rockers for years.
Setup is always simple.
Don't over complicate this... |
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JayP Samba Member
Joined: September 03, 2007 Posts: 34
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Posted: Thu Jun 17, 2021 6:43 am Post subject: Re: Scat 1.4 rockers geometry help |
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I will post pics later today. Yes, I meant the angles of the pushrod in the cup are the same at zero and full lift. Clatter, I understand what you mean about deviate from 90 degrees on the higher lift side, but that is impossible as I would have to lower the rockers even more which would put me off the lash cap. I will shim the setup until I get the proper swipe pattern and post pics. |
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JayP Samba Member
Joined: September 03, 2007 Posts: 34
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Posted: Fri Jun 18, 2021 4:14 pm Post subject: Re: Scat 1.4 rockers geometry help |
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OK, I will do this in 2 posts so it doesn't get confusing. Here is my current setup with no shims under the rockers. I would still need to lower the rockers .050" to get a just about perfect pushrod/adjuster alignment. With this setup, the swipe pattern is too low. The half lift photo is where it should be at zero lift. The photos are zero and half (full did not photo well) and pushrod/adjuster at 1/2 lift. Next post will be with .060" shims.
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JayP Samba Member
Joined: September 03, 2007 Posts: 34
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Posted: Fri Jun 18, 2021 4:18 pm Post subject: Re: Scat 1.4 rockers geometry help |
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I added .060" shims under the rockers, which gave me a much better wipe pattern. I am getting a below/center/above swipe pattern with this setup. Of course the pushrod/adjuster angle is now off, and I lost about .004-.005" lift this way. These photos are zero and 1/2 lift, and zero, 1/2, and full pushrod/adjuster angle. The angle of the cups at zero and full are not equal, but I like the swipe pattern. What do you guys think?
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Onceler Samba Member
Joined: May 28, 2010 Posts: 1646 Location: Indiana
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Posted: Fri Jun 18, 2021 5:06 pm Post subject: Re: Scat 1.4 rockers geometry help |
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That’s how my scats look with a .060 shim and how I’m running them. I entertained the idea of removing 1mm from the pad, but liked the idea of having the geometry correct closer to ~1/3 lift. Well that and I’m sure most folks run em straight out of the box anyway. _________________ 1972 Karmann Ghia |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Fri Jun 18, 2021 5:37 pm Post subject: Re: Scat 1.4 rockers geometry help |
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Yes, definitely looks better with the .060” shim. If you wanted to fine tune it, get a shim kit from CB Performance. You could check it with .015”, .030”, and .045” shims.
Shims are cheap...you’d probably be perfect at .045 (.015 + .030).
I think your good at .060” though |
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JayP Samba Member
Joined: September 03, 2007 Posts: 34
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Posted: Fri Jun 18, 2021 7:06 pm Post subject: Re: Scat 1.4 rockers geometry help |
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Thanks! Yeah, I like the swipe pattern, but I do have a bunch of shims that I can try to fine tune since I know now that the pushrod/adjuster is not going to line up properly. I will try .015, .030, and .040 shims just to see where they put me. |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Fri Jun 18, 2021 7:28 pm Post subject: Re: Scat 1.4 rockers geometry help |
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Get the pushrod thing out of your head |
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JayP Samba Member
Joined: September 03, 2007 Posts: 34
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Posted: Fri Jun 18, 2021 10:08 pm Post subject: Re: Scat 1.4 rockers geometry help |
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I know! I have just been spoiled over the years using high quality Pauter rockers on my race motors, where they fit like they are supposed to and everything lines up. It is hard to break habits! |
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challomoner Samba Member
Joined: October 13, 2010 Posts: 1195 Location: IRELAND
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Posted: Fri Jun 18, 2021 10:42 pm Post subject: Re: Scat 1.4 rockers geometry help |
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It looks like you've a lot of adjuster threads showing above the cup, another turn or two on the adjusters would straighten your adjustable pushrod at half lift. |
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mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
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Posted: Sat Jun 19, 2021 11:42 am Post subject: Re: Scat 1.4 rockers geometry help |
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the pushrods have ball joints. there is no aliginement...I do however like to square up the bottom of the rocker so all adjusters go up the same amount.( I also do a lot of lightening to them as that big blob is there so that rocker can also be a 1.34 ratio) every set of these type rockers Ive worked with need to go down .040"-.060"
never let the rocker run off the end of the lash cap.or the end of the rocker's"foot" .remember it is a "walking/slipper foot rocker" they walk and they slide too. the higher the lift the lower the rockers need to be. even jessell states this in the instructions of the $1000.+ ROCKER SYSTEMS .there is no this is it!! but with our stuff usualy .040" lower will put you pretty dam close.( I think Ive had 1 that was close to .060" lower.
I do commend you for using soft springs to check it..they give a true look at whats happening. |
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