273 rocker arm adjustment

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RR what do you mean the shaft having 3 holes? i had one hole, now i have zero holes, and i need to drill two holes and add a banana groove on one of those holes at 6 o clock

i still need to update the procedure we have been formulating for drilling the rocker arms and shafts,
There is the bottom (6 o'clock) hole with or without the banana groove plus the hole you will be drilling at 3 o'clock thru the rocker & shaft on the valve tip side and on the opposite (9 o'clock) pushrod side, the hole you will drill into the shaft past the already there hole in the rocker for a total of (3) holes. with the pushrod length corrected as needed either by adj pushrods or different pushrods & each pair of in/ex lobes on base circle (TDC compression for that cyl) & the rockers adjusted side to side with the proper addition of shims and slight spacing of the 5 holddowns so that everything is mocked up dead on & adjusters to zero pushrod clearance THEN with your holes already previously drilled in the rockers, scribe thru those 3 & 9 o'clock holes to make a circular mark(s) on the dykem on the shaft for where to drill. You will need to drive out then replace with new, the end plugs so you can deburr the ID of the shaft.
 
braze shut the top rocker hole. drill/tap/plug the outer 9 o'clock hole when done drilling thru (past) the inner hole (which is already there) & on thru the shaft. drill a hole thru the rocker/shaft at the 3 o'clock (right hand side) location. drill em (.100") with the cam on base circle. solder shut the small "side" holes in the shaft (you see two of em in the pic)
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ohhhh ok, yes the rocker arm has three holes, i thought you were talking about 3 holes in the shaft. The rocker arm will have two holes when i am done (access hole plugged with set screw, hole at 9 o clock, and top hole brazed shut, and drill one hole under the arm of the rocker at 3 oclock) then the shaft will have two holes when i am done. (remember my shafts only started with one hole, and i brazed that hole shut)
 
actually the shaft will have (3) holes (3 and 6 and 9 o'clock), 6 o'clock is already there (on the bottom) & you are adding 3 & 9 o'clock plus plugging the already there OE side in the shaft hole that is clocked wrong & the rocker will have (2) (3 & 9 o'clock) ,you are drilling the 3 o'clock hole & the inner 9 o'clock is already there & you are capping the top rocker hole & capping the outer 9 o'clock rocker hole when you are done drilling thru the already there 9 o'clock inner rocker hole into/thru the shaft.
 
here comes another keyboard full, but wait there is pictures at the end! LOL

Do we need to be concerned that the 3 o clock and 9 o clock holes will still line up, even though they are at different angles? Green highlighted line shows it going straight through. The blue line is what we talked about doing, which would oil the push rod and valve tip side at the same time. Pink line is proposed if we dont want the two holes to line up. Now i see what your saying nm9stheham. and that is a great idea by just moving the hole in the shaft instead of the rocker arm. So lets go with the blue line for drilling the rocker arm, and then when i transfer it to the shaft, i will just measure down about 1/8" of inch. This way the two holes dont line up at the same time, so it doesnt drop the oil pressure inside the shaft.

I am going to take my springs to work to check them on the spring tension gauge tester. Do i test them at my cam card valve lift of .472" (compress them with the tool) and with the inner spring also? im not sure what they are rated for and i want to know, also i can check to see if any of them are going bad. I can see my valve locks are taking a beating, i got new ones. There is also a shim under the valve spring, and those are getting chewed on a little bit from in the inner spring.

I like the idea of making the valve tip side rocker hole a little smaller, everyone good with 3/32" .093" ?

It was a pain staking process, but i was able to get good push rod measurements for all 16 locations. I had to think out side the box in order to get it done, very time consuming. First i tried electrical tape to hold the lower part of the adjustable push rod in the hole through the head. But then it wouldnt allow side to side movement. So then i found a pen tshirt clip, modified it to fit and thats what i used to hold the lower portion while spinning/adjusting the length. Then i had to mount a rocker arm to the shaft one at time and get on the base circle of the cam to get a good measurement. I came up with a average of 7.162" from bottom of ball to top of cup. I am going to send the info off to smith and bros and OE push rods, to see who can get them done for me before next weekend.

What should i make the three holes in the rocker shaft be? I was thinking of using this nice short stiff 1/8" drill bit, and then adding banana groove to the bottom hole with a die grinder.

Another thing i was confusing myself about, is that there is no rocker arm geometry adjustment with this setup. The sweep pattern is going to be alot bigger than a roller rocker, and the roller rockers have way to adjust for geometry either at the stud adjustment, or a way to shim the shaft up or down. With this setup we cannot change the geometry, just the push rod length. seems like these rocker tips have about a .250 sweep compared to a roller rocker about about .050. So in step #3 we might not need to check the sweep pattern with dykem, just put the lazer eye on them to make sure they are centered, because the factory setup has a ton of side play, clunk clunk.

Proposed proceedure:

#1 fill the top hole of the rocker arm using brazing material. (many different methods, just avoid putting to much heat into the rocker arm). I used tig brazing with silcone bronze tig rod, DC, negative eletrode 2% thoraided, no flux.

#2 Drill a 3/32" (.093") hole under the rocker arm tip (see picture), which will shoot oil out onto the top of the valve stem/rocker tip. At this point there will be three holes in the rocker. Later on we will plug the outside hole of the valve lash adjuster threaded bore using a drill, tap, and set screw with lock tite.

#3 need to locate the rockers laterally on the rocker shafts. Center rocker on each valve tip on rocker shafts using additional shims. .015" per pair of rockers. so the order goes like this: rocker shaft clamp with bolt, then a gap, then a rocker arm, gap, stock rocker arm spacer, gap, rocker arm, gap, clamp with bolt. so those four gaps need to add up to .015", in which ever order is necessary to get the rocker arm tips centered on the valve tips. set it up with best judgement, and then put some dykem on the valve tips, rotate the engine and check the pattern. once all the patterns are good, make a diagram of how to put it back together. I only got one shim kit, hopefully its going to be enough?

#4 solder shut the existing one hole in the rocker shafts (this is tricky, im not sure how you would solder them, but i used tig braze silcone broze and a belt sander eeeekkk to grind the high spots off, also found that the shafts have a chrome or hardening coating that chips off rather easily when i tried to machine the high spots off in the lathe), polish, and then paint dykem on the shafts completely. re assemble using the diagram made in step 3 without push rods. hold the rocker tips on the top of the valve tip, this represents being on the base circle of the cam where there is no load on rocker arm from the valve springs. this will allow the oil to rush in when there is no load (larger gaps). While holding the rocker arm onto the valve tip, use a assortment of oring picks to scribe a mark in the dykem on the shafts through the rocker arm holes at 3 and 9 o clock. Drill the 9 o clock hole with a 1/8" drill bit. Now on the 3 o clock hole, measure down 1/8" and mark it, and drill that location with a 1/8" drill bit. Now somewhere between those two holes on the bottom of the shaft, drill the 3rd hole (6 o clock) in the shaft with 1/8" drill bit (this is where the rocker shaft/arm takes all the load so oil is very needed here) and add the banana groove. de bur inside and out, berry hone inside of rockers and polish everything.

#5 now we can drill tap and plug that outer hole in the rocker arm with a set screw and loctite. some of the castings are irregular, there is a couple of mine that i will have to tig weld the set screw in because there is only enough meat for a half of a hole.

#6 for the final assembly adjust everything side to side till the holes line up before you evenly tighten/torque the 5 hold down bolts. Set the valve lash to cam card specs (in my case zero lash plus one turn) cold with no lube, then take them all part and lube everything up, then double check the side to side clearance.

There is a picture of a rocker arm mounted to bolt in a drill. this is how i am going to machine the top of the rocker arm for the jam nuts. the drill represents the lathe, and the tap represents an 11/16 end mill. I will spin it in the lathe and move the end mill in with the tail stock until it just touches and smooths it up, nice and square.

I am not a big fan of harbor freight, but this little belt sander has been handy! and cheap! also the fan to keep me cool, man its been hot...

Wow this has really been a process, want to get it right, but im running outta time... i have to work 60 hours next week, and then i have the weekend and thats it...eeekkk

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You outdid yourself! it'll take awhile to go thru it all. For now before you go to work take the springs with the inner springs AND the retainers in to check pressures. You would want to check em at the installed (closed) height they are mocked up at in the heads & the compressed (open) height they are at during mockup checking at zero lash/full lift. more later. I gotta a rough life, I'm gonna sleep till noon then watch the eclipse whose CL is 26 miles from me so I will get to see about a minute and a half of total darkness.
 
oh ya i forgot about measuring the installed height, got ahead of myself since i had them off, thought i would check them. But i will have to put one back on to measure what the installed height from top of bottom shim to top of spring retainor. Then put that in the spring press and then compress it the .472" and see how many pounds of force its putting out.

Also the picture of the 3 yellow dots on the shaft, i did that before i had the ah-ha moment that nm9stheham was talking about. Here is new picture, with the green dot moved down about 1/8" of an inch.

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important update....

Has anyone here done the drilling in the shafts themselves? How did they drill?

I just talked to Don at OE push rods and he had indicated that i may have a hard time drill those holes because they are hardened (this must have been that coating that i chipped off in in the lathe...EEKKK)

He had mentioned having the holes cut with a EDM (eletrical discharge machining)

He is going to sell me a set of push rods with my measurement of 7.162" end of ball to end of cup (which they said is an acceptable way to measure them)

Also going to buy a couple of the stock shafts from him for 25 each. (he says all the small block mopar racers use buy these shafts from him)

I know you guys are scrambling you get your eclipse sun glasses, LMAO.....(im going to use my a shade 14 welding lense) but when the eclipse is over, i am looking forward to your guys input on my latest keyboard full, i have this week and this weekend to get er dun...yeeehhawww

Thanks guys
 
Yes, those shafts are hardened. But you can drill it with a carbide bit. Just make sure your setup is rigid, or the drill will break (they don't bend at all).
 
The hold down 'saddle' under the rocker hold-down bolt is just a stamped piece so there is little precision there. Just be aware that the gaps may vary a bit, and the shim set between each may be all over the map.

Also, when you remove and rebolt the shaft assemblies, these hold down saddles can shift and so that can throw off the shim sets unless you consistently push each saddle to the left or right each time install it. You may want to mark each one with a left or right arrow and an UP mark, to keep it oriented the same way. In the snugging down process, I'd put the final torque on the center saddle first and work outwards each way.
 
yeah i got a set of .015" shims so i can really dial that stuff in, RR recommended no tighter than .015" per pair of rockers.

Here is a some pictures of the machine work to the top of the rockers.

Any other input guys on that last keyboard full, i would like to firm up that procedure.

I am getting 1/8" carbide drill bits, so i can drill those 48 holes in the rocker arms.... thats alot of holes.

I got my push rods ordered. they will be here friday.

I still gotta drill the hole in the rocker arms.

Then i can transfer the holes to the shaft, and measure down 1/8" on the 3 oclock side, and start going to town drilling holes...

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Just me I would center the 5 holddowns or better yet make/slip a metal sleeve of the right dimentions in the holddown hole to reduce the hole to match the bolt OD (to center the holddowns). File a small flat spot to get started drilling & lube the drill bit, it'll last longer (I'd be dead in the water if I did not have a Drill Doctor).
 
Everyone good with the hole locations in the shaft and rocker? The updated picture shows the two yellow and one green dot for the three holes in the shaft per rocker location With the bottom hole having the banana grove.

I see what you guys are talking about with the stamped steel hold downs. Good ideas. I can already tell that I am going to need to get more shims. I am going to order more next day air.

What do you guys think of the procedure?
 
I would go with the last pic 3/9 o'clock red straw locations & go with a smaller hole on the 3 o'clock side for the valve tip oiling as opposed to offsetting the 3 o'clock hole, since it has been brought up that the tip requires less oil. I would want em both drilled thru the shaft while on base circle so there would be a bit of dwell time for oil to shoot out. Since alignment is critical/precise both when drilling and when going together for final assy I would want a full circle hole drilled as opposed to a partial eclipse & use a smaller drill bit instead for the shaft drilling to modulate the flow. I would still go with the 1/8 on the rocker but less on the shaft to control it that way. alignment is a pain/needs to be dead on & a larger rocker hole helps in this regard. #1 get the alignment DEAD ON before you drill.
 
ok so lets make the two holes in the rocker arm 1/8" (.125")

The 3 oclock hole in the shaft 3/32" (.093"). 6 oclock hole in the shaft, 1/8" with banana groove, and the 9 oclock hole 1/8"

With alignment like this first picture with the 3 yellow dots

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So I got the holes drilled in the rockers. And I see a problem. The holes are under the top of the spring retainers...so if I drill the hole on the shaft while on the cam base circle the oil will miss the top of the valve tip.

So I would have to locate that oil hole lower on the shaft so when the valve is opening the top of spring retainer will be at a lower position so that the oil would spurt out on it.

Also drilled a test hole in a old shaft, using a cobalt bit and it drilled just fine. Doesn't appear to need carbide drill bits.

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that retainer OD sure looks way bigger than mine. yes for those, you would need to do your plan & drill the shaft with the rocker lower.
 
I have a feeling these are some heavy springs, I am going to measure them to find out. Those springs in the picture are the light springs for mock up. The new shafts I got from OE push rods, have the holes in a different location as the stock ones. I got my custom push rods, so I'm going be working all weekend to get er back to gether.
 
40 lbs at installed height, 200 lbs at full cam lift. So 160 lb springs.

In order to get the hole that is under the rocker arm to get oil of top of the valve retainer I had to mark and drill the shaft at full valve lift, and it's still boarder line.
 
40 lbs at installed height, 200 lbs at full cam lift. So 160 lb springs.

In order to get the hole that is under the rocker arm to get oil of top of the valve retainer I had to mark and drill the shaft at full valve lift, and it's still boarder line.


You need to correct your geometry. Just looking at the pictures you posted I can see the shafts are too low and too close to the valve. Contact B3 here at FABO and have him hook you up with one of his kits.

As for the oil hole under the retainer...let it go. There is plenty of splash coming off the springs to easily oil the valve stems.

I'd rather have the oil on the springs. The rest will take care of itself. Unless you are using springs with over 250 on the seat.
 
This is a excellent thread!

I have 2 sets of 273 arm set ups. Both came with banana groove shafts. I'm surprised the are not all that way. In the process of cleaning them up in a tumbler now.

Also, I have a very old Mopar Action magazine where Erehburg (spelling) showed all the differences in the rockerarm set ups for SB. He noted that adding the oil-hole just like they did on the econo-w2 rockers to the 273's rockers would be an upgrade. I'll try and post more info once I delve into my Mopar-library!
 
40 lbs at installed height, 200 lbs at full cam lift. So 160 lb springs.

In order to get the hole that is under the rocker arm to get oil of top of the valve retainer I had to mark and drill the shaft at full valve lift, and it's still boarder line.
Just saw this.. something is wrong in the installed height force measurement above; the stock springs were in the 60-80 lb range at installed height....???!

If that measurement is correct for the installed height, then these are the wrong springs.

And you don't spec spring rate by the closed-to-open-valve force difference....you take that difference and divide by the valve lift ( which is the spring compression closed to open). For example, if you did get a 160 lb difference closed to open, and the lift was .500", the spring rate is 160/.500" = 320 lbs/inch.
 
Very informative thread. I was searching looking for info on mods/upgrades using 273 adj rockers with X heads.
Not sure if I will have to clearance rockers or not. More stuff to consider lol. Also tempted to get new Crane style adjusters and locks.
Interested to see how it worked out for the OP?
 
It's going good so far, I still need to tear it down and inspect it this winter, to see how things are wearing. Alot of people are suggesting a geometry correction kit. I am thinking I should just make the jump and convert to roller rockers. I'm trying to get this done this winter so I can report back. I'm also working on upgrading my differential right now as well.
 
Very informative thread. I was searching looking for info on mods/upgrades using 273 adj rockers with X heads.
Not sure if I will have to clearance rockers or not. More stuff to consider lol. Also tempted to get new Crane style adjusters and locks.
Interested to see how it worked out for the OP?

Here is the thread I tried to link to earlier.

Reworking the 273 Adjustable Rockers
 
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