Wondering all things considered if 1.5s might buy me some real estate on the valve tip for better geometry.

If I shorten the valves and pushrods to widen the gap between the valve and rocker stud (the valve and rocker stud are like a triangle, lowering the 2 sides widens the gap) the spring install height suffers.. unless I consider different spec beehives with a reduced install height?

 

Nope, the 1.5 won't be any different, it has the same length from center pivot to roller tip....the difference in ratio comes from moving the pushrod cup closer or farther away frm the center pivot.

That current pattern will eat the guides right out of it.

a lash cap might get you enough surface to not get too close to the edge, but that would require a new retainers in 10°, the 10° locks with lash cap recess, and the lash caps......and still might not work out.

What you really need is a different rocker, one with a shorter pivot length. Straub has Harland Sharp make them for his sales, Crower also makes a backset rocker that would do a similar job.

 

This kinda crap happens all the time.
The angle of the studs and the angle of the valves make the tops of the studs and the top of the valve closer together the longer they get.
Like said above, the fix is a back set rocker or really long studs and really long pushrods so the centerline of the rocker trunnion and roller tip are running down hill toward the valve. That's a crappy way of doing because that causes other problems too. Or shorten the pushrod and do the best you can and live with it. .040-.060 wide pattern on the valve is a good place to be but sometime you have to compromise and deal with it at .100 wide and less guide life.

 

I’d take a look at both the height of the stud and pushrod length.

Lots in play here as studs come in variable lengths both in the bottom thread to the head boss and in the upper rocker end. To this end the use or not of sheet metal guides which result if used in the stud sitting higher above the boss than when sheet metal guides are not used.

The .1 longer pushrod is just a starting point for aftermarket aluminum heads. Factory GM heads use standard length pushrods as they don’t thicken the casting wall cross sections for added strength as the outside suppliers of aluminum heads do. Plus some totally race made heads add .2 inch to this dimension, so there is a lot to keep track off.

Changing rocker ratio will not have much effect as the ratio difference is all on the push rod side of the rocker.

Bogir

 

Those appear to be the Comp Aluminum rockers that are their budget rocker. Not to be a downer - I bought a set of them and at 15K miles the bearings were toast. I was perturbed to find out that they weren't rebuildable. I abought a set of Scorpions and have never looked back.

I'd follow Eric and John's advise - grab a set of rockers to resolve the issue - they'll be more money, but well worth it in the end.

 

Well how would I spec rockers with so many variables? Is there a trunion to roller center spec one can look for?

I enjoy building engines so don't mind having some parts down the road but at some point its gotta stop.

I'm gonna get a long 7/16 unc rod and use a reg nut to see what kind of results I'd get with a silly tall stud.. but just seems wrong. How does one navigate this bag of unknowns?

 

What I do, is measure with calipers looking for “B” in the drawing.
Start with the valve at half lift. Measure outside of the valve tip to outside of the stud 90’ to the valve stem. Write that down.
Subtract 1/2 the valve tip diameter, then subtract half the stud diameter and you have your center of trunnion to center of the rocker roller tip measurement to aim for. Then go shopping for as close as you can get to that.
When the parts arrive, do the usual half lift method for push rod length and order that length in your favorite brand.don’t forget to factor in the pushrod base radius.
I use Engine Pro and Trend a lot.

 

Thanks, is there a term for that spec? Can't recall seeing it before but now that I've run into this it should be right up there with the ratio!

Since I have the current rocker on i could measure it and subtract what I need to move it in, since its at the exact tip at half lift, I could subtract half the valve diameter (11/64?) and shop off that.. then I can fine tune it with pushrod length...

What I do, is measure with calipers looking for “B” in the drawing.
Start with the valve at half lift. Measure outside of the valve tip to outside of the stud 90’ to the valve stem. Write that down.
Subtract 1/2 the valve tip diameter, then subtract half the stud diameter and you have your center of trunnion to center of the rocker roller tip measurement to aim for. Then go shopping for as close as you can get to that.

 

Distance "B" in the above drawing is referred to as "pivot length".
I'm thinking 1.450"/1.460" is the common SBC dimension, looks like you need at least .050" less than that.

 

Tx again Eric, Found a catalog with jesel rocker specs listing pivot length. Any clue what else might work off the shelf?

These are 200cc Asian castings, copy of something im sure.

I'll measure the length today and get back, thanks.

Distance "B" in the above drawing is referred to as "pivot length".
I'm thinking 1.450"/1.460" is the common SBC dimension, looks like tou need at least .050" less than that.

 

Eric,
The small block fords are close at I think 1.510? Is that right? Which means many are too long to start with when cheap rockers are made to fit both SBC/SBF.

 

Man fantastic info fellas, thanks so much, learned a lot today .. I'll keep u posted.. def going to need longer studs and pushrods too by the looks of things.

 

T@D is also a quality place to shop.

 

1.3?

 

Thanks let me check mine little later and get back. Are those rebuildable with those c clips? Curious..

1.3?

 

That image I posted isn't exact;y correct. You wanna measure along this red line. It more accurate by hand to measure from the out side of the trunnion to the outsode of the roller tip and subtract both radii to get center to center. According to Crower Catolgue, it'll be 1.450

 

How about this?
I'm not that advanced yet to be learning about that radii stuff...

 

Still no. RIght angle, wrong number
Crower and says your PN will be 1.450 so unless there is something else going on I'm not aware of, you should be getting 1.450ish.

Measure A and divide by 2
Measure B and divide by 2
Write those down.
Measure C and subtract what you just wrote down.
It will be close to 1.450 and conformes what Crower says by the PN.

 

Thanks man! I learned something new today. New number is 1.445 Which is pretty close to what it was supposed to be.

Please excuse my chicken scratch!

 

Yes, enough to make you thirsty!
Check post #23. This is how I measured to come up with 1.445 which is supposed to be 1.45
I was close, LOL!

 

Did anyone else notice in post #1 that the valve keepers or retainers or valves themselves are not right? At least IMHO they aren't!

I would sure resolve that before worrying about buying pushrods and custom rockers. The keepers don't fit into the retainer like they should. Are they wrong size for the valve stem OD? Are they wrong angle or otherwise incorrect for the valve retainers? Looks like a disaster in the making if the engine is run. Once the retainers seat all the way, then the valve spring install height will have changed. Better take a good hard look.

Did you buy all the components and assemble the heads yourself?

 

Did anyone else notice in post #1 that the valve keepers or retainers or valves themselves are not right? At least IMHO they aren't!

I would sure resolve that before worrying about custom rockers. The keepers don't fit into the retainer like they should. Are they wrong size for the valve stem OD? Are they wrong angle or otherwise incorrect for the valve retainers? Looks like a disaster in the making if the engine is run. Once the retainers seat all the way, then the valve spring install height will have changed. Better take a good hard look.

Did you buy all the components and assemble the heads yourself?

I noticed that the retainer OD doesnt fit the spring at all, thought it might be a checking spring setup

 

Also, back to your original issue........ read post #8 here Procomp cylinder heads - The BangShift.com Forums

I would certainly check for consistency down the line of valves for straightness of the row and height. And also some measurement of location of stud relative to valve. You don't want to assume that what you observe on one valve will be the same for all valves. Lots of machined holes.

Sounds like the Procomp heads can be poorly made.

 

Agreed, I didn’t see this. Plus looking closer at the photo the straight edge really isn’t at 90 degrees, though this could be parallax in the photo positioning but overall my impression is the tools aren’t as aligned as they need to be.

The lack of alignment on the keepers to the retainer indicates that either the retainer is not seated to the keepers or there is a dimensional miss match that is common to mixing US and metric parts an example of which is a metric spring retainer designed for 8mm keepers with US sized 11/32nds keepers. This causes the keepers to sit proud of the retainer. This wouldn’t affect the rocker alignment to the valve stem but sure is likely to fail in operation.

To my eye the retainer looks like that used for beehive springs which if true these require Comp 787-16 keepers (locks) to bridge the difference in the metric dimension retainer that are designed for the 8mm LS valve stem to the Gen 1 and 2 use of 11/32nds valve stem.

We need the OP to report back on this.

Bogie

 

Ok all - i must be an idiot! Made a small error in my calculations! SO - I got a VERY narrow pattern just off center - about 45 thou! Im stoked - will need longer pushrods and longer studs - I found a 1.3" adjustable stud (ARP 354-7204) will give me almost 3/4 polylock engagement and leave me at the same height as the previously bought ARP 100-7101 studs incl en extra 100 thou screw in depth

* MISTAKE # 265 *
READ THIS: While speccing for studs, I made a mistake ingoing JUST by the adjustable threadlength, but this is incorrect, its the install height that counts as the threaded parts is machined at different heights!!

SO - MY ideal stud would be ARP 135-7202, the install height is 2.350 vs 1.9 I prev had, this will give me a 3/4 poly lock engagement.

ARP Stud specs for sbc's:
The Official ARP Web Site | Rocker Arm Studs

I am re-ordering 3/8 guide plates and pushrods as well (ill keep the 5/16s for a smaller build)-

Many of the parts I bought incorrectly will work very well with a smaller cam motor im gonna build-

this has been a MASSIVE learning curve!! in fact so much so that I would categorize ordering studs last as important as the pushrod! I ran out of length on mine it seems :/

Thanks for all the patience and help guys!

 

ok so I got the arp studs today and literally have 2 threads or less shy of what i needed, is it possible to thread the studs an extra 2 threads, or grind a washer down and put it under the polylock?

I see my polylocks are threaded all the way to the bottom, i literally need 2 turns to get some margin :/ if they had even the smallest of recess the threads wouldnt bottom out -

or should I order these? similar length but they are recessed at the tip -

 

I’d grind off the studs.
It should take you 15 minutes.
Make them flat too. Also make sure the grub screws are flat on the bottom.

 

I’d grind off the studs.
It should take you 15 minutes.
Make them flat too. Also make sure the grub screws are flat on the bottom.

I thought he was having a problem in the other direction from his description....he needs more thread down the shank of the rocker arm stud because the poly lock hits the ends of the thread process shoulder??

Fastarocka, if that is the issue, the counterbored nuts are the answer. i've run into that issue before.
Be aware there are a couple different OD's for the nuts, they have to clear the rocker slot so make sure you know what diameter your rockers need before ordering.

 

its not that the studs are too long but the polylock bottoms out about a turn before i have zero lash- the lock nut is another story, its about 3/4 in-

Anyway I ran my 7-16 fine die down each stud and just managed to get about 2.5 extra turns on the poly lock which worked out perfect - i used specd a slightly shorter push rod to move the wear pattern away from the outer edge a tiny bit and it just just took me past the max on the stud - i could have ordered 7.6" pushrods but a: they were almost twice the price, and b: i wanted the pattern a little more inward as it was nearing the edge some - i just measured my 90 degrees at about 85 to result in a slightly shorter pushrod and the pattern is a little farther from being near the edge.. pattern depth is still about 50 thou which is still very good- if I had to order polylocks separately i would try get ones witha little recess in the bottom to give a little more adjustment- but so many variables!

Heck ive had WAY more trouble with this valvetrain geometry than anything else ive had to do!! Just glad i finally "get it"

 

The rocker trunion shaft needs to be positioned on the stud with its flat side facing up, is this how you are installing them?

Bogie

 

yes - i did note it had the flat surface for the polylock to engage on- thanks for checking - that would be a disastrous mishap tho- i usually can at least figure out what looks right or wrong haha..

 

I've never done it before but I bet a hardened AN machine bushing under the nut would work out.
You cut more threads so it sounds like you got that solved though. I doubt it's a problem, or going to be a problem, avoid sharp edges on the new cut threads to help prevent the studs from fracturing. The studs are under the most stress at the shoulder radious just below the threads.

 

That's a good idea - Whats the verdict on the hex lock nut sticking out by 2-3 threads?

This is my current situation:

I've never done it before but I bet a hardened AN machine bushing under the nut would work out.