rocker geometry and adj. push rod

Streetbuggy · Post by **Streetbuggy** » Sun Sep 03, 2006 11:29 am

Having read through all the rocker geometry info on here and the samba. I thought id have no problem doing mine (2110 new build)

i have an adjustable push rod but its a pain in the a**. The adjuster is at one end so when its in you cant get to it.

shall i just make one with it in the middle, do you get the same readings if you do it with weak valve springs instead of the dual ones?

thanks

500LbGorilla · Post by **500LbGorilla** » Sun Sep 03, 2006 1:24 pm

You get close enough measurements as long as your parts are clean and lined up correctly, even with weak springs. You are shooting for something that can go 0.010" either way even if you measure closely enough. They won't all be the same, so you shoot for an average, and for pushrod length, you shoot for the one that gives you the least adjuster room. That means you need to check all of them and use the shortest measurement of alll of them. Unless you want to have all of them cut differently (uh, no.)

Yeah, you need one with an adjuster in the middle. Leaving your pushrod tube off makes it quite easy to set up geometry with weak springs.

Max Welton · Post by **Max Welton** » Sun Sep 03, 2006 1:51 pm

Make one.

http://66.225.214.60/ghia/MVC-426F.JPG

Streetbuggy · Post by **Streetbuggy** » Sun Sep 03, 2006 3:38 pm

i did make one, but it bent in the middle. i think i cut it down to much, as the threaded rod bent, may be because i didnt take the second set of springs out. This is my first big engine so its a steep learning curve, but thats how you learn,right.

Streetbuggy · Post by **Streetbuggy** » Sun Sep 03, 2006 3:40 pm

oh and do i need pedistal shim or can i get away with shortening he push rod, have read that you only need the shims with swivel fet adjusters. im using the CB forged 1.4:1 rockers.

500LbGorilla · Post by **500LbGorilla** » Sun Sep 03, 2006 4:26 pm

You need shims if your GEOMETRY needs them, not to make space. With adjusters, if they are too thick and your geometry is ok, you back-cut the rockers to make space for them.

Streetbuggy · Post by **Streetbuggy** » Sun Sep 03, 2006 4:44 pm

cool, ill see what happens tomorrow, when i take out the small spring to stop the push rod bending.

Streetbuggy · Post by **Streetbuggy** » Tue Sep 05, 2006 6:41 am

Right then.

How do i know if and what shims i need under the rockers? something to do with the position of rocker on valve?

The difference between open and closed is around 14mm (average from a few goes) so thats 0.551". When i shorten the pushrod to make correct geometry at 1/2 lift i dont get anywhere near this lift.

Ive included some pics of open and closed showing rocker to valve contact, also are the springs binding, they seem close near the retainer.

VALVE CLOSED

VALVE OPEN

500LbGorilla · Post by **500LbGorilla** » Tue Sep 05, 2006 8:46 am

Go to zero lift. Screw your adjuster out until it bottoms on the back of the rocker. Then open it about 1 1/2 to 2 turns. Adjust your pushrod until it is at zero lash and then take your rocker to HALF lift. Snap a shot like the ones you already have, and then a shot of your adjuster and all. As sideways a shot as you can get, like this:

The one in my shot is not set up right, but that's the shot. What you want at half lift:

* Tip centered as much as possible on the lash cap (vertically)
* Adjuster as in-line as possible with the pushrod
* If you draw a line through the contact point of the rocker to the lash cap, perpendicular to the valve stem length, you want it to bisect the rocker shaft right at centerline.

You'll not get all three of these perfect, most likely, but something close to all of them is good. That's how I did mine, and after 18K miles with dual springs, my guides, lash caps, and rockers are perfect. Once you get these things set, by using the right shims under the rockers (I didn't need any shims), then you measure your pushrod length as you have it set. Do not use the adjuster to change anything.. it doesn't. But having it 1.5 to 2 turns out ensures that you will have room to adjust valves and it won't be so far out that rocker rotation will cause a lot of vertical motion of the pushrod on action.

Streetbuggy · Post by **Streetbuggy** » Tue Sep 05, 2006 11:13 am

think im finally getting my head round this. Its only taken 2 days, i was over complicating things.

so adjuster is 2 turns from bottom, pushrod adjusted to zero lash.

how do i work out what shims to buy
side view

adjuster view, sorry meant its not as straight as it looks

500LbGorilla · Post by **500LbGorilla** » Tue Sep 05, 2006 11:25 am

Look at what would happen if you shim it. The adjuster would be MORE out of whack. What you COULD use is a thicker lash cap.

From your shot, it is not possible to see the rest of the scenario though.

Streetbuggy · Post by **Streetbuggy** » Tue Sep 05, 2006 11:36 am

if its shimmed the adjuster will angle up more, right?

so this is not right and i need to look fo some thicker lash caps?

what else you need to see?

Do i have to put the pushrod in and adjust it to zero lash on each valve to check the length on them all?

500LbGorilla · Post by **500LbGorilla** » Tue Sep 05, 2006 11:44 am

I can't see how the tip is centered on the lash cap. I can't see the contact area on the lash cap to see how the centerline looks.

Yeah, thicker lashcaps to solve the one problem, the others are probably ok.

You CAN run it as it is with the adjuster slightly off. It won't hurt, but it could be a little better with the thicker lash cap. I sure wouldn't put ANY spacers in on that setup.

Streetbuggy · Post by **Streetbuggy** » Tue Sep 05, 2006 12:03 pm

in the above pic side view you can see it touching the lash cap.
Also in my first 2 oics you can see it from side.

centre view

Was hard to get them off centred, due to side play shims and the width of the foot