Rocker Geometry....

[dive!dive!]

Folks,
Yes, I know this has probably been covered many times, but please bear with me...
I understand the basics of the concept and have the tools to measure, but there appears to be conflicting advice :
1) Standard wisdom says have the adjusting screw in line with the valve stem at half lift
2) Some say get the adjuster in line at full lift
3) others say have the top of the valve / foot at 90deg through the rocker center
4) lastly , their is a view that its the up/down movement of the rocker on the valve top through the full open/close that should be minimised
All, I assume are attempting to reduce valve guide wear.

My specifics are that I have Scat ProStreet 1.25 rockers on some 044'sa that have had a fair bit of flycutting. My rockers have the adjuster at the valve end and the foot is the retained ballbearing with a flat face type
I've set it up so that my adjuster is in line with the valve stem at half lift. This has required 0.170" of shims. This seems a lot and I've been told its too much. Some advice has been to grind back the rockers to allow the adjuster to be wound up further. Other advice has been to put in say 60thou of shims and just make sure the movement on the valve tip has an equal amount of upward / downward 'push' through the cycle.

Is .170" of shims too  much ? any other advice gratefully received !!
Cheers
Steve

[Goin Postal]

I used those adjusters before and had the same problem. My advise is get a set of Gene Berg Elephant Feet adjusters. That will solve your problem because they aren't as fat as the balls. They are much easier to use too. You never have to deal with a ball that's rotated while you're adjusting your valves.

[Donny B.]

Welcome to the Lounge Gary. How's it going?  Still back east?

I agree with Gary on the adjusters.  I screwed up once with those and had the rocker come back and damage the socket.  Eventually it ejected the ball and I broke a lot of stuff.  This was my fault for not getting the geometry correct.  I would bet the Berg adjusters are lighter too.

[dive!dive!]

Hmmm. Not sure I can change the adjusters - the later Scat ones are 3/8 thread, not 8 or 9mm.

Donny B :  can you expand on this : I screwed up once with those and had the rocker come back and damage the socket ? What did you do wrong ?

So. What are my options. Is 170 thou of shim too much ? Should I grind the rocker arm ? If I do, what about the oil hole alignment ?

I don't mind spending time to get it right but it sure is a PITA...

[Goin Postal]

I would measure how much you can remove without having an oil hole alignment issue and then remove what you need. Otherwise your only choice is to use the .170 shims. Or maybe cut away some threads for oil passage?
Hey Donny. Does the B stand for Baked Beans. Yeah, still back east missing the beans.

[Donny B.]

Gary glad you liked the beans...

When I said that I screwed up I meant that the rocker was low on the pushrod end.  That caused the adjuster to contact the retainer as it rocked back damaging the socket for the ball.  Eventually the ball got ejected and the rocker with now just a socked attached release the keeper causing dropped valve which the piston immediately banged into.  It was my fault but that didn't make me feel any better.  Some folks grind underside of the boss the adjuster threads into for more clearance and that seems to work.  I never liked doing that, thought it weakened the rocker.   you will need to stack the shims high for proper geometry.  Hope that clarifies it for you.

[modnrod]

If the geometry is correct and you are happy with it, and you don't mind using 2 rocker cover gaskets together (yep, I've done it too  ), then it's all good really. It isn't ideal though, longer pushrods, marginal adjuster cup clearances, etc, etc. I have also ground the rocker as well in preference before too.

I'm a bit older now and a fair bit less tolerant, so I would send them back to Scat in a box and say "These are crap! Get it right!", then buy some that work well without major mods.

[dive!dive!]

Hmmm.
Thanks
I had thought about alternate rockers. Which ones are 'correct' ? I need 1:1.25's
Steve

[modnrod]

Which ones are 'correct' ? I need 1:1.25's
Steve

Good question.
Answer from me is, I dunno.
I'm hoping that CBs new 1.3 forged rockers are OK, coz that at least was going to be my choice (but again, I don't really know).
I would have run Pauter rollers even on a mild street build, but find it hard to justify the cost, when I can get twice the amount of rockers from Yella Terra for the same price.............

[dive!dive!]

I had looked at the Pauter Roller 1.3's as well......yes, expensive, and I don't mind the cost as long as they are 'right'....but that would be a bit of a gamble....and if I'm spending that much I'd probably change cam for a 1.4 ratio type....
I'll take another look at the geometry on Friday. I'll also see how much I could grind the rockers if I go that route and lastly i'm going to look at less shims (say .1") and determine at what % opening the adjuster is aligned.
Cheers
Steve

[Goin Postal]

Have you looked at CB part # 1692?

[Martin S.]

I used this cheap set from CIP (in the 1.4 size) and they worked perfectly on my turbo (only $109). http://www2.cip1.com/ProductDetails.asp?ProductCode=C13-21-2162
Remember to order lash caps. The adjuster is better on the pushrod end. I have thousands of miles on my street engine and valves haven't even needed much adjustment. Here's a vid showing how they are set up. http://youtu.be/xX3iaHUI-SA

[DKK Ted]

Those are the Chinese rockers, they are really not bad, had a set of 1.4's and had Berg install there hardware, shafts are better, sold those to a friend. also did a set of same rocker's but 1.25's, did the same, with Berg hardware. Those I run currently in my motor that's in my car now, no issues, no problem's. Geometry work out nice.

Ted

[modnrod]

Very cool info, thanks guys.

[richie]

Are you using an adjustable pushrod right now?  I have used those rockers and never needed to do that much shim[had to use 0.120 but only as customer wanted to keep his existing pushrods] but only have used them on vw casting heads not 044s
When you say you must have 1.25s is that because you must have that lift? the scat pro 1.25s are nice and will solve some of you issues but on those flycut 044s they may come out more than 1.25

cheers Richie 

[dive!dive!]

Hi Richie
Yes, all checked with an adjustable rod....actual lift at the retainer is bang on (give or take a thou or three:-))
The cam I have isn't ideal for anything more than 1.25's so I'd like to stick with the 1.25's - they worked fine prior to this headwork especially as I've kept the rest of the valvetrain nice and light (single springs, ally rods, ti retainers etc)
Hopefully have some time tomorrow to look at it again...
Steve

[Martin S.]

Have you looked at the Berg instructions for determining pushrod length, etc.? I've used that in the past and it worked ok. You've indicated in your first post how many opinions you will find online. 50% of what you read on the internet is not right.

[dive!dive!]

Berg instructions

Thanks Martin, that's one I haven't read, and cant seem to find on the berg site, if anyone can direct me to a copy, that would be great.
Cheers

[Martin S.]

Looks like it's out of print. I'll look at mine this weekend and see if I can snap a pic of that section.

[dive!dive!]

Right. Found some 'garage time' this morning.
I've ended up grinding the rockers back a little - so I have about 40thou of adjustment. I've also extended the oil channel on the adjuster by a thread or two so I still get oil when its wound back into the rocker.
Now with 60thou of shims and my original pushrods, its not bad at all. I get the adjuster lined up with the valve stem at 55-60% open. I reckon that's ok.......
Cheers
Steve