Reworking the 273 Adjustable Rockers

[toolmanmike]

Just as a point of reference. I have a pair of originals around. To get the oil hole to line up with the adjusting nut hole in the rocker, I had to remove and reverse the rocker. Then it looks like it lined up. Aparently? the previous owner had these assembled wrong.

 

[Jadaharabi]

there are 3 places where the oil flow TO the rocker shafts is limited:
1. The 'oiling interrupter' holes in the cam: .049 sq inch flow area and about a 5-6% duty cycle per calculations and some estimating
2. The head bolt to oil passage clearance inside the head, approx .050-.060" sq inch flow area with standard head bolts; this will get restricted down further if the ARP head studs are used, since the studs are considerably thicker than the bolts.
3. The clearance between the rocker shaft hold down bolt and the hole in the rocker shaft through which it passes;

So the rockers will rise in level to some level due to this pulsating oil flow and the level will fall due to the outflow from the shaft. With some RPM's I think the shaft will fill fairly well, BUT for the pushrod oiling holes to be effective, the shaft has to fill higher since it is 'uphill'.

1. If you haven't read Guitar Jone's Sticky titled "Anyone interested in my oiling mods I did." page 7 or 8 I think talks about the restriction of the oil passage to the head by turning the cam bearing. Then drill a hole thru to the main oil galley to make the heads full time oiling.
They also make cams with groves around the #2 and #4 journals for full time oiling. This is fine for a street motor but not a racing motor.
2. Never used studs. Not aloud in NHRA stock as far as I know. So you know more about this than I do.
3. Unless you have drilled out the holes for bigger hold down bolts this should not be a problem. On the original 273 shafts that is I've never used after market so don"t know about them.

If your using a high volume pump the rocker shafts will always be full. The pressure will vary with the different rpm levels but they never will drain out all the oil.

The thread was started to show how to fix the rocker pushrod, valve tip gaulding problem.
Now it has gotten interesting with all the input from you guys. An Yellow Rose saved my engine by getting me to check my rocker shafts. I found where my engine assembler put them in upside down plus he did not remove the plugs in the end of the shafts and clean them out. My bad.

Now over on the right side of the post were it says 'edit" or "quote" is a "Thanks" button feel free to push it anytime you see it.

 

[chrispy1971gtx]

Interesting topic. I just picked up a good used set of 273 rockers. I'm assuming they all had banana-groove shafts. The set I got was in good shape, but the interference fit on several of them were pretty much wore out. I called SmithBrothers pushrods and got a complete set of adjusters with quality locking nuts for around $85. I simply ran a tap thru to chase/clean the threads, and installed.

 

[toolmanmike]

Just as a point of reference. I have a pair of originals around. To get the oil hole to line up with the adjusting nut hole in the rocker, I had to remove and reverse the rocker. Then it looks like it lined up. Aparently? the previous owner had these assembled wrong.

Another thing I noticed with my set, there is only one oil hole per rocker and it looks like it should go towards the head (to the bottom) where all the wear is and all the oil is needed. What ever works its way around the shaft to the adjuster hole must be enough for a stock engine to keep the ball and cup lubricated. The small hole in the top must be there for spray to help cool the springs and to help lube the rocker tip to valve tip. There is no specific hole for that. All of my rockers have the holes in the top. Those of you that have plugged holes in a few of your rockers, I wonder if those rockers were placed below the pcv valve or oil fill cap to help prevent them from sucking or leaking oil. As we know, valve covers without baffles can be a problem that way and rockers that don't squirt oil directly at them could help the problem.

 

[nm9stheham]

3. Unless you have drilled out the [shaft] holes for bigger hold down bolts this should not be a problem.

I mention the clearance of the rocker hold down bolt to the rocker shaft mounting holes because it is one of the 3 restrictions in series in the supply to the rocker shaft that are in the same range of size. It is not a matter of it being a problem as much as one to be aware of. In fact, the PRW AL rocker shafts that we have in our 340 have the shaft mounting hole SMALLER than the stock shaft's mounting hole, and that hole's clearance to the rocker mounting bolt/stud becomes the primary oil flow restriction to the rocker shafts in that particular setup.

IMHO, good thread here because of a lot of varied objective input, all constructive.

 

[Jadaharabi]

Another thing I noticed with my set, there is only one oil hole per rocker and it looks like it should go towards the head (to the bottom) where all the wear is and all the oil is needed. What ever works its way around the shaft to the adjuster hole must be enough for a stock engine to keep the ball and cup lubricated. The small hole in the top must be there for spray to help cool the springs and to help lube the rocker tip to valve tip. There is no specific hole for that. All of my rockers have the holes in the top. Those of you that have plugged holes in a few of your rockers, I wonder if those rockers were placed below the pcv valve or oil fill cap to help prevent them from sucking or leaking oil. As we know, valve covers without baffles can be a problem that way and rockers that don't squirt oil directly at them could help the problem.

I think you are using the shafts from a stamp steel rocker not the adjustable rocker ones. If so they are the perfect candidate for drilling holes where they need to be.
The hole in the top of the arm is to cool and lube the rocker and valve stem plus cool the moving parts of the valve assembly.
However this for a low rpm stock type motor not a 6000+ rpm one. At elevated rpm the oil is flung off the arm then while in suspension the rocker arm is beating it in to a spray mist.
A lack of a baffle can be messy as in oily messy.

In my pictures you see the bottom banana grove is forward of the hold down bolt. The back hole on the pushrod side is directly below the oil hole in the rocker arm for the pushrod oiling. These pictures are on the rear of the passenger side. Note that my notch is down where it should be.

Thank you again Yellow Rose, I just discovered that 4 of my rockers are rubbing the valve springs. That's what I get for letting a bowtie person assemble my motor.

 

[Rapid Robert]

OK what I have is a circle track 360 coming together. extensive oiling mods (Sanborn/Guitar Jones). hi vol pump. FT head oiling with .080" orifice setscrews in the decks (not assembled so I can go up or down on them). So far on the 273 rockers: capped top hole/drilled hole on valve side (per drill bit pic) to .100" & will up that to 1/8". the shafts are on the bench but I would & do install em with notch down and to the rear on pass side and down and to the front on dr side. the shafts I have have the bottom hole with banana grooves and the side hole 63 deg away from that bottom hole (I forgot to note today which side). I will plug the current holes with shot. (1) How should I finish this out? drill the hole under the valve tip from .100 out to 1/8 and and what clocking do I drill it further into the shaft? Valve closed? Just this (1) hole on the valve tip side? I do have other shafts & some do not have the banana groove on bottom just the slightly offset hole on the bottom and NO side hole. I await further instructions! RR PS now to throw a "monkey" wrench into the works! solid MP cam and hyd lifters which I took apart & added a spacer so the cup is higher and just under the snap ring so that I can use my current cup/ball pushrods! not sure if they are 273 ones or not but they are close enough to be dead on correct length for my mockup checks (1) thread showing (I wanted a bit more) & the cup is a bit close to the rocker at full lift but does clear OK. everyone tells me it will grenade on test and tune night! All I did was convert hyd lifters to soild so I could get the cup height I wanted so as to not have to purchase new pushrods. I feel lucky

 

[Jadaharabi]

(1) FT head oiling with .080" orifice setscrews in the decks (not assembled so I can go up or down on them). (2) I will plug the current holes with shot. (3) How should I finish this out? drill the hole under the valve tip from .100 out to 1/8 and (4) what clocking do I drill it further into the shaft? Valve closed? Just this (1) hole on the valve tip side?
RR PS now to throw a "monkey" wrench into the works! (5)solid MP cam and hyd lifters which I took apart & added a spacer so the cup is higher and just under the snap ring so that I can use my current cup/ball pushrods! not sure if they are 273 ones or not but they are close enough to be dead on correct length for my mockup checks (6) (1) thread showing (I wanted a bit more) & the cup is a bit close to the rocker at full lift but does clear OK. everyone tells me it will grenade on test and tune night! (7)All I did was convert hyd lifters to soild so I could get the cup height I wanted so as to not have to purchase new pushrods. (7)I feel lucky

1 Do NOT restrict the oil going to the head.
2 if your shafts already have the 2 holes per rocker why do you want to plug them an drill more. You have plugged the leak on the rocker so oil is going to the pushrod now that was being lost. You plugged the hole on top and drilled the new oiling hole for the valve and rocker tip your good to go on the rocker arms.
3 .100 to .125 is a 25 percent increase in diameter isn't that a 100 percent increase in volume correct me someone if I'm wrong.
4 See answer 2
5 I don't think you want to do this. A solid lifter cam has different ramp speed an profile than a hydraulic one. Did you replace the wire clips with C clips? All it takes is a loose adjuster an a wire clip will leave the building.
6 1 thread is about perfect I thought maybe I'm wrong
7 Buy the new pushrods go with the solids

Jad PS hope your not using a stock oil pump pickup for the HV pump especially with the Guitar Jones mods.

 

[nm9stheham]

The increase in hole size from .100 to .125" is about a 50% increase in flow. But it is not just flow.....it is a matter pressure too if you want these holes to physically squirt the oil over onto the springs and retainers. Personally, I would stick with the .100" for this reason. You are adding a lot of flow outlets in the shaft now, and will have much greater outflow area than just with the standard rocker oiling holes and grooves. My concern would be with the level of oil and pressure in the shafts dropping too much.

I agree on ditching the head flow restrictor IF you are not using the full flow cam bearings or grooved cam journals. The flow area of a .080" diameter restrictor is about .005 sq inches.... which is only around 1/10th of the area of the standard LA design flow restrictions. If you are using the full flow cam bearings or journals, then I would expect some restrictor is in order to protect the mains.

FWIW, the flow restrictor makes more sense if you are using roller rockers in some circumstances; those do not have the same flow restriction at the rocker that the standard shaft rockers do.

 

[j par]

Interesting topic. I just picked up a good used set of 273 rockers. I'm assuming they all had banana-groove shafts. The set I got was in good shape, but the interference fit on several of them were pretty much wore out. I called SmithBrothers pushrods and got a complete set of adjusters with quality locking nuts for around $85. I simply ran a tap thru to chase/clean the threads, and installed.

I paid $48 from summit. Here's a tip from triple-R : lightly file down the top were the jam nut goes to give it a flat landing spot.
View attachment 20150227_210007.jpg

 

[Rapid Robert]

1 Do NOT restrict the oil going to the head.
2 if your shafts already have the 2 holes per rocker why do you want to plug them an drill more. You have plugged the leak on the rocker so oil is going to the pushrod now that was being lost. You plugged the hole on top and drilled the new oiling hole for the valve and rocker tip your good to go on the rocker arms.
3 .100 to .125 is a 25 percent increase in diameter isn't that a 100 percent increase in volume correct me someone if I'm wrong.
4 See answer 2
5 I don't think you want to do this. A solid lifter cam has different ramp speed an profile than a hydraulic one. Did you replace the wire clips with C clips? All it takes is a loose adjuster an a wire clip will leave the building.
6 1 thread is about perfect I thought maybe I'm wrong
7 Buy the new pushrods go with the solids

Jad PS hope your not using a stock oil pump pickup for the HV pump especially with the Guitar Jones mods.

Jad, thanks for hanging with me on this. (1) I have full time oiling to the heads & I drilled the setscrews to .080". If you want more or less than that let me know & I will drill em out further or get new setscrews & drill em smaller (2) I was thinking that you and Yellow Rose wanted me to plug the offset hole(s) with lead shot & drill a new one(s) in line with the valve tip (the drill bit pic) with the valve closed, correct/clarify me on that. (3) I had rockers that already had the top brazed shut and the hole under the arm on the valve tip side (drill bit pic) drilled to .100". You wanted 1/8 so I am going to open em up a hair to that per your direction. (5) I am not useing a hyd lifter on a solid cam (the ramp issue I understand), I am using a hyd lifter locked solid into a solid lifter on a solid cam & now that you mention that I will replace the wimpy retainer rings with good clips. (6) good to hear that (1) thread is good. (7) I feel lucky! Holler back when you can. EDIT yes hi vol pump/ 5/8 ID pickup/plumbing 1/2 NPT pipes, wish my camera was functioning!, extensive mods head to toe

 

[Thumperdart]

At high rpm the oil is slung off of the top of the rocker arm so I tapped the hole on top part way down with a #6 tap. Then i put red locktight on a soft #6 screw and tighten it till it snaps in two. I then grind the stud down flat. I then drill a 1/8 hole under the arm that is pointing up toward the tip.

Appreciate the effort but w/all of the work involved, I`d rather buy new modern rollers............more accurate ratios cos those are all over the place.........:coffee2:

 

[Jadaharabi]

Jad, thanks for hanging with me on this. (1) I have full time oiling to the heads & I drilled the setscrews to .080". If you want more or less than that let me know & I will drill em out further or get new setscrews & drill em smaller (2) I was thinking that you and Yellow Rose wanted me to plug the offset hole(s) with lead shot & drill a new one(s) in line with the valve tip (the drill bit pic) with the valve closed, correct/clarify me on that. (3) I had rockers that already had the top brazed shut and the hole under the arm on the valve tip side (drill bit pic) drilled to .100". You wanted 1/8 so I am going to open em up a hair to that per your direction. (5) I am not useing a hyd lifter on a solid cam (the ramp issue I understand), I am using a hyd lifter locked solid into a solid lifter on a solid cam & now that you mention that I will replace the wimpy retainer rings with good clips. (6) good to hear that (1) thread is good. (7) I feel lucky! Holler back when you can. EDIT yes hi vol pump/ 5/8 ID pickup/plumbing 1/2 NPT pipes, wish my camera was functioning!, extensive mods head to toe

(1) Remove the set screws and lock them in a drawer. You do not want to restrict the flow of oil to the heads.
(2) If you have the shafts with the 2 sets of holes. Put the rockers on the head with the spacers. No pushrods. Remove the adjuster screw. If you have already plugged hole on the push rod side. Then bend a wire and isert it in thru the adjuster hole to the shaft. Now rock the rocker arm back on the shaft and see if the wire doesn't go into the hole in the shaft. Mine do. your should too.
(3) Stay with the .100
(4) Where did 4 go?
(5)The bottom of a solid and the bottom of a hydraulic lifter have different tapers. You are using a modified hydralic lifter with a curved face on a flat tappet cam. You will destroy everything you are working for. Put a hydraulic cam in place of the solid cam and the lifters will work.
(6) 1 thread is what is recommended
(7) you are lucky LOL

I want too see your oil pump and pickup

 

[Jadaharabi]

I paid $48 from summit. Here's a tip from triple-R : lightly file down the top were the jam nut goes to give it a flat landing spot.

Thank you this is good to know.

 

[yellow rose]

(1) Remove the set screws and lock them in a drawer. You do not want to restrict the flow of oil to the heads.
(2) If you have the shafts with the 2 sets of holes. Put the rockers on the head with the spacers. No pushrods. Remove the adjuster screw. If you have already plugged hole on the push rod side. Then bend a wire and isert it in thru the adjuster hole to the shaft. Now rock the rocker arm back on the shaft and see if the wire doesn't go into the hole in the shaft. Mine do. your should too.
(3) Stay with the .100
(4) Where did 4 go?
(5) You are using a modified hydralic lifter with a curved face on a flat tappet cam. You will destroy everything you are working for. Put a hydraulic cam in place of the solid cam and the lifters will work.
(6) 1 thread is what is recommended
(7) you are lucky LOL



I want too see your oil pump and pickup

As I mentioned, I have never had a set of OE 273 rocker shafts. If you do what you are saying with a piece of wire and it goes through the rocker shaft and out the hole in the rocker with the rocker on the valve stem at your installed height, then you are golden. If not, it needs to be corrected.

And I agree 100% on NOT ever restricting oil flow to the rockers. Ever. The system is self limiting, especially as the rpm's get higher you have less time to get oil up there. When I am doing all out stuff I enlarge the feed to the cam, the feed from the cam to the deck and the feed hole in the head.

Never restrict oil going up to the head. It's a killer.

Thanks for the pictures. What I am saying is much easier pictured.

 

[Jadaharabi]

The increase in hole size from .100 to .125" is about a 50% increase in flow. But it is not just flow.....it is a matter pressure too if you want these holes to physically squirt the oil over onto the springs and retainers. Personally, I would stick with the .100" for this reason. You are adding a lot of flow outlets in the shaft now, and will have much greater outflow area than just with the standard rocker oiling holes and grooves. My concern would be with the level of oil and pressure in the shafts dropping too much.

Thanks for the correction.
I have read to use both sizes. i am going to change to the .100 for now and see how it works.

Haven't added any new holes to the shafts. On the rockers I've plugged 2 holes and added 1

 

[Rapid Robert]

here's the pickup/NPT pipes! looks worse in the pic than it does in person & I just tossed em on there today with no alignment just to take a pic. (1) my "drill bit photo" hole is drilled to 1/8. should I drill on thru into the shaft & if so should it be with valve closed? should I do anything to the adjuster screw side other than plug the side (outside) hole that Ma drilled for the inner adjuster screw hole? should I plug the shaft "side" hole that is 63 deg from bottom bananna grooves/hole?

 

[Jadaharabi]

here's the pickup/NPT pipes! looks worse in the pic than it does in person & I just tossed em on there today with no alignment just to take a pic. (1) my "drill bit photo" hole is drilled to 1/8. should I drill on thru into the shaft & if so should it be with valve closed? should I do anything to the adjuster screw side other than plug the side (outside) hole that Ma drilled for the inner adjuster screw hole? should I plug the shaft "side" hole that is 63 deg from bottom bananna grooves/hole?

(1)How far out did you drill the pump body?
(2) You are going to set the pickup about an 1/8" off the bottom of the pan and brace it?
(3) Is that 1/2" npt?
(4) Is the pipe screwed in to the pump or into an adapter?

I'm not drilling my shafts untill I test the holes already in them. Then i will decide weather to drill them or not.
Make sure your rockers are not rubbing the valve spring also.
I hope you canned the hydraulic"solid" lifters on a solid lifter cam idea an went with a hydraulic cam instead.

 

[Rapid Robert]

(1) drilled in far enough so I could tap enough threads so I felt comfortable with the depth of the pipe into the pump body when it reached "tight" for a secure connection (2) yes I am going to brace it roughly in the middle at a good point & I dont have my sheet in here but iirc a hair under 1/8 (3) yes hardware store NPT pipes! (4) nipple screwed into pump directly, no adapter. the big problem I am having (other than time/money and motivation) is when I ground the 273 rockers on the valve grinder the face is at a slight angle (& I mean side to side/not correct), not the normal "arc" they have from the pivoting on the grinder when done correctly and the way the rocker sweep over the valve tip. I could only get the apparatus to work (antique Sioux 622N) by grinding it on the side of the wheel. I trued the wheel and the pivoting holder is secure/appears to be level & the rocker appears to be vertical inbetween the two convex "cones" that secure it but something ain't right. Earlier I was able to get it to grind on the front of the stone but the rocker was way above the centerline of the stone "horizontle" plane & that was even worse. What am I missing! EDIT I have 5/16 clearance, maybe a hair or two less when it all compresses

 

[Jadaharabi]

(1) the big problem I am having (other than time/money and motivation) is when I ground the 273 rockers on the valve grinder the face is at a slight angle (& I mean side to side/not correct), not the normal "arc" they have from the pivoting on the grinder when done correctly and the way the rocker sweep over the valve tip. I could only get the apparatus to work (antique Sioux 622N) by grinding it on the side of the wheel. I trued the wheel and the pivoting holder is secure/appears to be level & the rocker appears to be vertical in between the two convex "cones" that secure it but something ain't right. Earlier I was able to get it to grind on the front of the stone but the rocker was way above the center line of the stone "horizontal" plane & that was even worse. What am I missing! EDIT (2)I have 5/16 clearance, maybe a hair or two less when it all compresses

(1) Why are you grinding on the tip of the arm?????
(2) With the pushrod out and the rockers bolted down does the body of your rocker arms rub the spring or retainer when you move them up and down?
(3) What size drill bit did you use for 1/2 NPT?

 

[Rapid Robert]

(1) there is a slight "trough" worn in the rocker arm tip where it contacts the valve tip. (2) I checked them on mockup & I'm OK (3) I think the chart wants a 11/16 drill bit but in my exp the tap tends to be too tight in alot of cases with the stated bit dia so I go a bit larger tho a 23/64 might be hard to come by & I've been sitting on this pump for awhile so I dont remember what I used exactly and more often than not it taps too hard so I go at it with a straight non tapered porting burr around and around carefully as to keep the hole concentric. the valve grinder has the swing arm attachment to do the rocker arms. just a touch to smooth em up, but what am I missing on that machine???

 

[Jadaharabi]

(1) The valve grinder has the swing arm attachment to do the rocker arms. just a touch to smooth em up, but what am I missing on that machine???

Sorry, i'm not familiar with your machine.

Thanks for the oil pump info.
I think you mean 23/32.

 

[Jadaharabi]

Thanks for the oil pump info.
I think you mean 23/32.

With your idea here is what I have come up with so far. Using a 11/16 drill and a 1/2npt tap.

The tube is a Small Block 727 dipstick tube. still working on it. Might cut the end off of the Milodon tube. Thread it put it in the coupler and weld it.

 

[Jadaharabi]

With your idea here is what I have come up with so far. Using a 11/16 drill and a 1/2npt tap.

Found the greatest deal at Harbor Freight on a 6 piece NPT Tap and Die set.

Those are the burrs and dreimal tool stones I use to clean up inside the pump housing.

 

[Rapid Robert]

that is the same HF set I bought, it was cheap enough & I dont tap that much. Seems like it want a larger drill size than the spec. But I'm gonna recheck my dimentions as I"m going in too many different directions right now. Jad if I can back up a step: (1) Should I drill a hole in the shaft on the valve side? (2) if so should I clock it with the valve closed? top rocker hole is closed and side rocker access hole that Ma drilled is closed with a setscrew. (3) Should I drill a hole in the shaft (in the pushrod/adjuster side)? (4) if so how should I clock it? I will checkout the trans dipstick tube as I have extras. I kinda figured the plumbing pipes was overkill! but it was the only idea I could come up with at the time. RR PS I will when I have time read back on your posts as you may have already answered my Q's. Thanks bro.