lifter galley crossover tube
Well ok between the two post about creating a low pressure point being mentioned do we have an agreement that you can have full oil pressure at your gauge and certain areas starving for oil because of low pressure?
I may be mistaken but I do not believe that I gave velocity as the cause of the 2&4 mains.
You are correct there is no point in grooving the cam grooves as this hurts the main bearings. As I said most cam manufacturers no longer do this. It was another tried in the past experiment that does not help, just like cross drilling.
I believe that older Chevy small blocks were fed from a center galley that was not used to feed the lifters and that this galley was dead ended at the end so no velocity issues there.
In a previous post I mentioned that the plug being added at the end of the galley is not discussed enough.
The cross over tube method and the tubing the block method both have in common adding a plug to dead end the system. The only difference is where the plug is. One is over top of #1 main feed passage and the other is in front of it with the #1 passage blocked from the #1 main bearing. This plug also helps stop the velocity.
You are correct that the rocker oiling mod by itself does not make the block into a priority main oil system. But it is a step towards it.
It is my understanding that an "R" block does not come with any feed passages drilled to the lifters so you do not have to tube the block.
Lifter oiling is always optional on a full race motor.
Regarding the straight shot oiling I also mentioned that the location of the oil holes has been refined. Not that it was new.
There is a trend now towards oiling the rockers with external lines tapped into the main galley. I believe Jim sizilgys jumper tube mod accomplishes the same thing.
Still can't let go of velocity, huh? Ya know, I'm supposed to be on vacation with my family this week, so I'm not going to waste it here. This is it, unless this thread is still going strong next week.
I understand pressure differentials, and fluid dynamics. If I didn't, my education in race engine technology would have been a waste. You assumed that I didn't know that pressures will be different across a fluid system. Of course they will, but that doesn't mean what you're saying is correct. Take a commercial compressed air system, for example. They start of with a huge primary pipe, with a lot of volume. But, by the time it gets to the work station, it is 1/4" pipe. Why? Because over a run, pressure will drop unless the volume is increased, or the restriction is increased. It is how pressure is maintained. I used the exact same principles when plumbing my house, so the shower wouldn't be reduced to a trickle when someone turned on the kitchen faucet. An engine block is the same way. The bearing feed galleys are the smaller than the main galley. But, the cam, and cylinder head feeds are the same size as the bearing feeds, so your grooved cam reduced the pressure drastically at the main bearings. By the way, there are a lot of solid rollers still available with the oil groove, even though it's a bad idea, IMO.
You've been talking about velocity all this time, and the failure with your engine, and then, all of a sudden, velocity had nothing to do with it. Without resistance to flow, there is no pressure. It can be lower at different points throughout the system, and will be, but putting a plug at the end of a galley, and then pulling the same volume of oil out of that galley in a crossover tube, does nothing to change that low pressure area. The pressure will still drop over that run, especially with the bleeding along the way. You can argue until your blue, but it doesn't change the physics.
Your SBC example is flawed as well. The passage that feeds the mains is not the main galley. If I had a nickel for every Chevy guy who thought his small block had priority main oiling from the factory, I'd be wealthy. The main galley on a SBC is from the pump, up to the trident, that feeds three separate galleys. Two are the lifter bores, and the other feeds the CAM first, and then finally the mains. And you think that plug at the front of the block reduces the imaginary velocity? Why did someone invent rev kits, if a lifter popping out of the bore and dumping oil wasn't a bad thing? After all, the oil isn't going to flow to the low pressure area anyway.
My point about the straight shot oiling, is that Chrysler has always used it, since at least 1958, but Chevy guys tend to think it is only exclusive to them. The Scat info you posting is new marketing of a very old, but viable, design. Take a look at marketing strategies and you'll see what I mean.
There is not a trend to use external lines to oil the rocker gear, unless the heads are deisigned that way, i.e. Indy 440-1, or spray bar oiling is being used. Aside from that, the mods are internal, and not new by any stretch.
Until next week......