Rat Bastid
Dunamis Metron
Ok, I’m massively disappointed. First, IF your rockers have the oil hole in the rocker clocked where Chrysler put it then you use the 9/32 inch measurement. So it’s about .281 and it is plus zero minus .050 not the other way around.
The only rockers I have on hand are the MP aluminum rockers. They are the same as the Crane gold rockers just blue. I had no idea until I dug these out that they have the oil hole lowered in the rocker body. I don’t know if Crane did that or Chrysler. Either way, it sucks because you can’t use the 9/32 measurement.
When looking at these pictures you’ll see there is an undercut area on the adjuster. That undercut and where it is relative to the oil feed hole in the rocker is critical.
In theory, while the valves are on the seat and there is lash in the rocker there is going to be oil blowing out of the hole in the rocker, hitting the undercut and running down into the cup. This is all predicated on some things. One is at idle and low engine speeds you have enough oil volume and pressure at the rocker to get the oil to blow out of the hole and onto the adjuster. Low volume/pressure at idle won’t feed the bulldog. You will smoke adjusters. And here is the big issue (as if the flow and pressure thing wasn’t bad enough) the hole in the rocker MUST and by MUST I mean ABSOLUTELY MUST line up with the hole in the shaft or you will have issues.
If you are running a SFT cam with low spring pressure this isn’t usually a thing. But a solid roller and some decent spring pressure and it is critical. And you might be surprised that many times the hole in the rocker is never lined up with the hole in the shaft.
Going further down the rabbit hole...the only way I know to correct the hole alignment between the rocker and the shaft is to mock everything up like it’s going to run. Use machinists blueing on the shafts. Then bolt the shaft and rockers on the head, lined up side to side and with the geometry corrected (the lined up and geometry corrected is important) and take a sharp scribe and stick it in the oil hole in the rocker and mark the shaft where the hole in the rocker is. Then you have to take all that apart, get a really sharp carbide center drill or something similar and drill the hole in the shaft where it goes.
Ok, back to adjuster protrusion. If you have rockers where the oil feed hole is right at the bottom of the threads then use the 9/32 measurement. If the hole is lower than the bottom of the threads you have to eyeball the protrusion. Yes, it’s stupid. That lowered hole was done (as told to me by Chase Knight at Crane) that that was done because everyone was running pushrods too short so the lowered the hole to stop smoking adjusters. Don’t tell people how to fix it. Just drop the hole. And that’s bad because even though it’s a relatively small amount, it does change the rocker ratio. The further out the adjuster is, the further it is away from the center of the shaft and that changes the ratio. So it’s a suck suck deal. Now to the pictures.
I’m starting with this picture because you can see by the arrows pointing to the black sharpie dot where the oil feed hole SHOULD be. In fact, it should be up a bit more but that’s as good as I could get with a sharpie. It really should break through right at the bottom of the threads.
If the hole was in that location, the 9/32 measurement is the correct measurement to use. Since the hole in this rocker is lower than it should be, the 9/32 measurement is wrong. You have to eyeball the protrusion.
In this picture you can see how far out the adjuster is. This is because the oil feed hole is so low in the rocker. That adjuster is about .375 out. That would smoke adjusters if the oil hole was in the correct location.
^^^Double picture^^^
This picture shows the 9/32 protrusion and this is what you use IF the oil hole is at the bottom of the threads. In the pictures you can see the undercut area and that’s what you want to get in the correct position so oil coming out of the rocker hits that undercut and runs down into the cup.
One can argue that this system is Rube Goldberg through and through you wouldn’t be wrong. But it does work IF the hole in the rocker lines up with the hole in the shaft while the valves are in the seat and the adjuster is correctly positioned according to where the oil feed hole in the rocker is.
I hope everyone isn’t confused on this, but once you understand the relationship of the hole in the rocker to the undercut on the adjuster. If you get everything right, this system will oil the adjusters to well over 8500 rpm with 900 pounds of spring pressure over the nose.
Here is a picture of 4 pushrods. I don’t have any single or double taper pushrods in the shop. I thought I had some single tapers out there but I can’t find them.
From the bottom is an OE pushrod which is good for dead stock stuff only. After that, but something better.
Second from the bottom is a Smith Brothers 3/8 heavy wall pushrod. This is a good pushrod for what it is. A SFT cam should be able to use these unless it’s a W2 head. The double offset of the lifter bank angle and rocker offset of W2 will push these to the limit.
The top 2 pushrods are Smith Brothers heavy wall 7/16 pieces. These are good pushrods. You can see by the arrows that these have been under duress. The round mark is from the pushrod bending (yup...it sure did bend) and in bending it was rubbing the head at Max lift. There was over .125 clearance where it was rubbing and it moved that far. This was an intake pushrod.
The hash marks the other pushrod are from a lifter failure and the link bar came around and beat the crap out of the pushrod. The lifter failed on an intake lobe and that pushrod was on an exhaust.
Probably way too much information but it’s all important. You have to set adjuster protrusion by where the oil feed hole is. I believe on your Norris rockers the oil hole is right at the threads where it should be. If that’s the case, it’s 9/32 minus .050 plus zero.
If your oil feed hole is lower than the bottom of the threads you have to set adjuster protrusion so the undercut is lined up with the hole in the rocker.
One other thing to note is once you get to a 3/8 pushrod you start getting into clearance issues. A 7/16 pushrod is worse. Especially at the bottom of the pushrod tunnel. You may have to grind out enough materiel from the tunnel that you break through the intake flange. If that’s what it takes it’s ok. A single taper 7/16-3/8 will make fitting the pushrod a bit easier and the 3/8-7/16 double taper gets you the same clearance through the tunnel with the extra diameter of 7/16 in the middle.
The only rockers I have on hand are the MP aluminum rockers. They are the same as the Crane gold rockers just blue. I had no idea until I dug these out that they have the oil hole lowered in the rocker body. I don’t know if Crane did that or Chrysler. Either way, it sucks because you can’t use the 9/32 measurement.
When looking at these pictures you’ll see there is an undercut area on the adjuster. That undercut and where it is relative to the oil feed hole in the rocker is critical.
In theory, while the valves are on the seat and there is lash in the rocker there is going to be oil blowing out of the hole in the rocker, hitting the undercut and running down into the cup. This is all predicated on some things. One is at idle and low engine speeds you have enough oil volume and pressure at the rocker to get the oil to blow out of the hole and onto the adjuster. Low volume/pressure at idle won’t feed the bulldog. You will smoke adjusters. And here is the big issue (as if the flow and pressure thing wasn’t bad enough) the hole in the rocker MUST and by MUST I mean ABSOLUTELY MUST line up with the hole in the shaft or you will have issues.
If you are running a SFT cam with low spring pressure this isn’t usually a thing. But a solid roller and some decent spring pressure and it is critical. And you might be surprised that many times the hole in the rocker is never lined up with the hole in the shaft.
Going further down the rabbit hole...the only way I know to correct the hole alignment between the rocker and the shaft is to mock everything up like it’s going to run. Use machinists blueing on the shafts. Then bolt the shaft and rockers on the head, lined up side to side and with the geometry corrected (the lined up and geometry corrected is important) and take a sharp scribe and stick it in the oil hole in the rocker and mark the shaft where the hole in the rocker is. Then you have to take all that apart, get a really sharp carbide center drill or something similar and drill the hole in the shaft where it goes.
Ok, back to adjuster protrusion. If you have rockers where the oil feed hole is right at the bottom of the threads then use the 9/32 measurement. If the hole is lower than the bottom of the threads you have to eyeball the protrusion. Yes, it’s stupid. That lowered hole was done (as told to me by Chase Knight at Crane) that that was done because everyone was running pushrods too short so the lowered the hole to stop smoking adjusters. Don’t tell people how to fix it. Just drop the hole. And that’s bad because even though it’s a relatively small amount, it does change the rocker ratio. The further out the adjuster is, the further it is away from the center of the shaft and that changes the ratio. So it’s a suck suck deal. Now to the pictures.
I’m starting with this picture because you can see by the arrows pointing to the black sharpie dot where the oil feed hole SHOULD be. In fact, it should be up a bit more but that’s as good as I could get with a sharpie. It really should break through right at the bottom of the threads.
If the hole was in that location, the 9/32 measurement is the correct measurement to use. Since the hole in this rocker is lower than it should be, the 9/32 measurement is wrong. You have to eyeball the protrusion.
In this picture you can see how far out the adjuster is. This is because the oil feed hole is so low in the rocker. That adjuster is about .375 out. That would smoke adjusters if the oil hole was in the correct location.
^^^Double picture^^^
This picture shows the 9/32 protrusion and this is what you use IF the oil hole is at the bottom of the threads. In the pictures you can see the undercut area and that’s what you want to get in the correct position so oil coming out of the rocker hits that undercut and runs down into the cup.
One can argue that this system is Rube Goldberg through and through you wouldn’t be wrong. But it does work IF the hole in the rocker lines up with the hole in the shaft while the valves are in the seat and the adjuster is correctly positioned according to where the oil feed hole in the rocker is.
I hope everyone isn’t confused on this, but once you understand the relationship of the hole in the rocker to the undercut on the adjuster. If you get everything right, this system will oil the adjusters to well over 8500 rpm with 900 pounds of spring pressure over the nose.
Here is a picture of 4 pushrods. I don’t have any single or double taper pushrods in the shop. I thought I had some single tapers out there but I can’t find them.
From the bottom is an OE pushrod which is good for dead stock stuff only. After that, but something better.
Second from the bottom is a Smith Brothers 3/8 heavy wall pushrod. This is a good pushrod for what it is. A SFT cam should be able to use these unless it’s a W2 head. The double offset of the lifter bank angle and rocker offset of W2 will push these to the limit.
The top 2 pushrods are Smith Brothers heavy wall 7/16 pieces. These are good pushrods. You can see by the arrows that these have been under duress. The round mark is from the pushrod bending (yup...it sure did bend) and in bending it was rubbing the head at Max lift. There was over .125 clearance where it was rubbing and it moved that far. This was an intake pushrod.
The hash marks the other pushrod are from a lifter failure and the link bar came around and beat the crap out of the pushrod. The lifter failed on an intake lobe and that pushrod was on an exhaust.
Probably way too much information but it’s all important. You have to set adjuster protrusion by where the oil feed hole is. I believe on your Norris rockers the oil hole is right at the threads where it should be. If that’s the case, it’s 9/32 minus .050 plus zero.
If your oil feed hole is lower than the bottom of the threads you have to set adjuster protrusion so the undercut is lined up with the hole in the rocker.
One other thing to note is once you get to a 3/8 pushrod you start getting into clearance issues. A 7/16 pushrod is worse. Especially at the bottom of the pushrod tunnel. You may have to grind out enough materiel from the tunnel that you break through the intake flange. If that’s what it takes it’s ok. A single taper 7/16-3/8 will make fitting the pushrod a bit easier and the 3/8-7/16 double taper gets you the same clearance through the tunnel with the extra diameter of 7/16 in the middle.
