Having trouble finding rockers to fit AFR heads

[j-rho]

Thanks folks, should be able to find a black Sharpie.

These are the retainers: http://www.airflowresearch.com/afr-8505 ... -x-750-id/

The valve stems do have a beveled/chamfered edge. This pic shows it better: https://www.amazon.com/photos/share/u6z ... 1kzwIHxN5I

Checked the invoice, these are the valves:
8mm 2.020 +100L Race Int Valve 0.00
8mm 1.600 +100L Race Exh Valve 0.00

Occurs to me now, the +100L is probably .1" longer? Worried with lash caps, making the valve even longer still, necessitating moving up the rocker fulcrum, will push things further to the exhaust side? Or does the lash cap extend the usable surface area atop the valve, making that ok?

[Paul Kane]

Hi everyone,

I can't seem to find a set of rocker arms that fit and still provide decent geometry.

Thanks!!!

The images you've provided show only that you are having clearance issues, nothing more.

j-rho, where the roller tip ride atop the valve stem as nothing whatsoever to do with valve train geometry....you need to get that "centered roller wheel" crap out of your head. Let the roller wheel fall where it may and instead focus on the geometry itself, because adjusting the pushrod length in order to desperately center the roller wheel top the valve is almost always at the expense of optimized valve train geometry.

The primary purpose of the roller wheel is not to reduce friction, it is there to minimize valve guide wear in highly loaded valve train systems no matter where the rocker tip rests atop the valve stem....most people don't understand this and mistakenly presume it's there for friction reduction. But a roller wheel hardly rolls at all; it's primary purpose is to continually maintain its loading to be in-line with the valve stem as the rocker travels through it's radial arc.

So let the roller wheel fall where it may and instead focus on optimizing the rocker arm geometry. Should you remain head strong in centering that roller atop the valve, then the chances of maximum horsepower and maximum valve train stability will go down, while the chances of catastrophic engine failure will go up.

[j-rho]

Hi Paul,
Thanks for the note. I have made much progress in moving my head forward , thanks largely to the video provided earlier in this thread by cstraub. The geometry of the situation, preserving cam signal by minimizing sweep, makes sense.

There have been accompanying statements made like "anywhere is fine as long as it's in the middle 2/3", which I haven't seen outwardly contested? I read on another site where Smokey Yunick or somebody was ok with the position as long as it wasn't less than .020" from the edge. How do people feel about those sentiments, which I'm too inexperienced to have my own opinion of? Middle 2/3 on an 8mm valve would mean not getting within ~.052" of the edge.

[hereinmissoula]

Afr195 here , comp rockers , just ordered these mid 2016 . Ad performance. 8019 valve spring upgrade . No problems .

[hereinmissoula]

And this was with initial pushrods , which were too short . 7.250 with morel 4602. Needed longer .

I use foxwell/straub method . Has worked on every motor I have built !

Just finished this 460bbc, flat solid , race-rite oval motor . Worked yet again .

[ZEOHSIX]

The less sweep across the valve tip the LESS SIDE FORCES against the valve guide. I'm OK with a little compromise....it wouldn't hurt to invest $20 in an adjustable length pushrod to find the optimum pushrod length.....when checking make sure to take in account head gasket thickness. You the guy who has to AutoX Camaro as I recall.....don't get led of on a tangent by people talking "mid lift" geometry and other such subjects....your building an "Endurance" motor not running a NHRA "Stocker" looking for every last HP. Black "Sharpie" across the valve or steal your wife's darkest color of lipstick when she's not looking....shoot for best sweep centered at valve tip centerline. The length of the pushrod will dictate the contact between rocker arm and valve tip. Comp Cams sells an adjustable push rod.

Here's the Comp one at Summit: https://www.summitracing.com/parts/cca-7703-1/overview/

[hereinmissoula]

Have to disagree with above post ... Though I don't have road race experience. Mid lift 90* has given me best geometry ...

[wyrmrider]

Superpursuit
The rocker does not know what motor it's on
we're just interested in the arm length on one side to get the roller over the valve and on the other side to get some pushrod clearance.
You have motors with not a lot of choice of rocker arms B O P Cad AMC you use what works

j-
it's not length in the same place
the + 100 is giving you some more spring installed height
but the tip length from the keeper grove to the tip is making it tough to get clearance
yes if you do the geometry you will be moving the center of the lash cap a little closer to the stud but you pick up a ton more area on top of the valvestem and a ton more clearance for your retainers

that with the chamfer on the stem and a hard surface for your roller make a lash cap a good way to go
especially since you have the TI retainers

if that pic is at mid lift- roller out to the ex side as far as it goes when at mid lift your are golden for that “problem”
you do NOT want to sacrifice mid lift geometry for retainer clearance- so go with the lash cap
DO NOT just raise the fulcrum (having the fulcrum a little lower is not as big a sin but not possible here)
+100L is probably .1" longer? yes
Worried with lash caps, making the valve even longer still, very slightly .060-.080 .090 thickness of the cap

necessitating moving up the rocker fulcrum, YES that's what's going to give you retainer clearance
will push things further to the exhaust side? Very slightly
Or does the lash cap extend the usable surface area atop the valve, yes it does and also covers the chamfer and gives you a harder surface
making that ok? ABSOLUTELY

some other good posts today – starting with the next one by Paul
“primary purpose is to continually maintain its loading to be in-line with the valve stem as the rocker travels through it's radial arc.
“ we can explain this if you are interested
hereinmissoula - good point-- too short pushrods are no good

and one other- let's ignore the last post except for the adj pushrod


and I've run much closer to the edge a la Smokey
where you can get in trouble is being near the edge at the top or bottom where the rocker is on an angle

when you measure for pushrods be sure and adjust for valve lash x rocker ratio you want to use net lift not gross cam lift

[hereinmissoula]

Only pic I have of valve tips before rockers

[j-rho]

Black Sharpie went a little better, if catching the result in just the right light:
https://www.amazon.com/photos/share/pjT ... rH5hfsIOjF

Did the neighboring valve too:
https://www.amazon.com/photos/share/6s2 ... uqtv9IoBmS

Clearance to the retainer is tight, but it feels like this setup could work. Ordered up some 8mm lash caps anyway, see how it looks with them installed.

[wyrmrider]

If that's using the Foxwell method you are golden
I'd run the lash caps anyway just to make sure I have a paperclip worth of clearance around each of those expensive TI retainers
since you can't remove the springs -- some of the tight spots are hard to see
set up for 3/8 pushrods?

[kimosabi]

A little late to the party here, just wanna add that on AFR heads it seems you will need longer studs and a shorter rocker tip to get it golden. Straub/Foxwell recommended I got a custom set from HS and Randy there was very helpful. 0.050 shorter rockers and sweep got nearly non existant, got pretty close but inside to where you're touching the tip right now. Nitpicking I would get the rockers even shorter, 0.070 would be super duper but as mentioned, that would be nitpicking and "unnecessary."

I was in the same boat, .360 lobe and AFR 210 heads +.100 valves but I never had clearance issues with beehives. Just major geometry gremlins.

[j-rho]

Lash caps arrived. Very happy with how things ended up. Tried several different lengths of my adjustable pushrod, and the one that gave smallest sweep (measured about .042") does so at a place that doesn't look too far outboard now that there's a larger surface to work on. Still not centered but that's OK!

set up for 3/8 pushrods?

The supplied guide plates dictate use of 5/16" pushrods -

IMPORTANT* 5/16” THICK WALL CHROME MOLY HEAT TREATED
PUSHRODS SHOULD BE USED TO AVOID WEAR OF THE PUSHROD
FROM CONTACT WITH THE GUIDE PLATE.

Length I've worked out is 8.1". Figuring the regular .080" wall ones would be ok (like so: https://www.summitracing.com/parts/cca- ... /overview/)?