Squishy, dry-sumped 2276 build thread

[brewsy]

Looking good. Really nice work and as you say the Pro builders are good but nobody is going to put this much attention into your engine than you..
Cant wait for more.

Cheers

[Clatter]

Oh, I love me some thorough motor building like this!

Ray vallero (RIP) had a couple of .060"(IIRC) holes drilled in the pushrods up near the adjusters.
The pushrods spin when in use, and hop up and down, so it was like a Rain-Bird sprinkler for the springs, guides, etc.
His build is on the Samba, but all of the pictures got lost, unfortunately..

I have filed a groove in the side of the rocker, adjacent to the shim, from the shaft pointing at the lash cap.
Not sure it helps, but it seems like it would aim a spray of oil at the rocker pad..

There is also the idea of drilling thru the rocker casting to spray straight at the lash cap.
If you have ever seen some Toyota rods, the rod/bearing is drilled to aim at the bottom of the wrist pin.
Kinda like that..

Or you could do this with the rods..
Or do grooves, like in the type 4 'bulletin'.
Pison squirters?


WRT case venting,
Remember that you have adjacent cylinders going in opposite directions.
The air/oil underneath each piston needs somewhere to go, and the adjacent cylinder needs the opposite.
This means that the more easily the vulume of the cylinder can move across the case, the les power you use.
Even if it is a vacuum..
So, even if it is a dry sump, you want to minimize 'pumping losses'.
Especially with bigger bore/stroke,
Especially with counterweights in the way.
I am of the opinion we always see oil leaks with performance VWs because they have too much internal pressure, in places, at times during hard running.

Not just porting the case, but also polishing the inside?

Did you ever see the fully polished and knife-edged crank by the user here 'The Astronaut'?
Maybe he was on TOS.. Can't remember..

This is just TOO good..

Love it when you can do some finessing to parts to have a win-win-win.

More power, more efficiency, longer life.. All for doing some work - not nessesarily even buying any parts.

[Crawdad]

Thanks for the encouragement, fellas. I've been tied up with other aspects of the car lately, hence the radio silence.

I am coming round to the idea of doing some case porting. If I manage to get 5 inches of vacuum in the case, that would count as success, but it leaves about 25 inches (of mercury) worth of air getting pumped around.

Speaking of reducing pumping losses, I will be drilling and tapping a new port to the CB dry sump pump, which will feed in parallel with the existing port (on the pressure side) to the main gallery. Stay tuned for that.

I would be tempted to install some 911 piston oil squirters (with the check ball: they stay closed with low oil pressure at idle), but I think the CB DS pump is pretty tapped-out, volume wise, without adding those. The pressure side gears are only 21mm. I am already adding a volume demand with the Hoover mods, so I need to be careful with my oil-volume budget. But I think I will go ahead and open up those minuscule holes in the adjuster screws.

[Crawdad]

I haven't died. I got distracted with 1. all the minutiae of doing a Subaru 5-speed swap (word to the wise: it will cost you twice what you thought it would) and 2. prepping the bones of the car, pictured here. Believe it or not, this represents a lot of progress!

[Crawdad]

Tomorrow I am sending parts out to be coated with a dry film lubricant: main, rod and cam bearings (mainly to reduce the psychological trauma of dry starts), piston skirts (since they are forged, I am running .045 clearance, so they will be knocking around when cold), rocker shafts, valve springs (the inner spring rubs against the outer spring, and apparently this contributes significantly to oil temps), timing gears (since I am running a dry sump, they won't be running in an oil bath), oil pump gears (mainly to reduce scoring on the pump body) and, after much trepidation, the lifters. This touches on all the voodoo surrounding cam break-in. One coating guy I talked to put it this way: "Look, the ideal break-in is none." I said, "yeah, but what about the fact the lifter needs to rotate? If there isn't enough 'grab' between the lobe and the lifter, maybe it won't rotate?" He thinks the lifter rotates simply because it is going up and down while resting on the tapered face of the cam lobe. That sounds right to me.

[MarioVelotta]

Dang man, great thread. I'll be ordering a couple new tools now

[Crawdad]

A bit of case porting pictured here. I also enlarged the oil-return passages near the cam, and the grooves in the cam bearing saddles that feed oil to the heads. Aluminum chips everywhere!

[Crawdad]

Of course the whole point of porting the case is to reduce the pumping losses associated with moving air back and forth between front (1/3) end of the case and the rear (2/4) end, by enlarging the passages the air must pass through. I am also venting the case, hoping to achieve some vacuum. Instead of venting at the valve covers or at the generator stand, why not extract the air pressure as close as possible to where it is generated? That should further reduce pumping losses, since the air won't have to travel up the push rod tubes to the rocker boxes, or through the small and convoluted path to the generator stand. I drilled directly into the top of the case for two vents, one at the front end and one on the rear. In locating them, I wanted to minimize the amount of oil spray that enters the vent. My hope is that by lining the vents up with the center line of the rods, oil slinging out of the rod bearings will hit on either side of the vent, leaving the vent in the shadow of the spray.

[Crawdad]

The other big consideration in locating the vents is interference. I mocked up the alternator and fan shroud and found that the front vent could really only be in one spot, given the rod-shadow effect I was going for: on the 1/2 side, with a right-angle fitting ground down as needed. I also needed to put a substantial dimple in the bottom of the fan shroud to make it clear the fitting. For that I used an air hammer with a brass tool that is intended for a metal-shaping technique called form-flowing. Here I just used it for bashing, but in a nice controlled way. I'm not worried about this dimple disrupting air flow in the shroud; it's nice and smooth.

[Crawdad]

OIL PUMP
It would be truly embarrassing to admit how much time I have invested in this freaking pump. I could have learned to play the violin, or speak Chinese or something. But nothing is too good for Precious.

Some of that time was wasted in trying to make a fixture (on a borrowed milling machine) that would allow me to cut FOUR o-ring grooves on the pump (one on either side of the ports where it mates to the case, and one on each face of this two-stage dry sump pump). That came to naught, and I ended up just using an old oil pump as a fixture for cutting a groove for the one o-ring that really matters, the one that prevents the pump from sucking air from the inside of the case due to a loose fit in its bore. I used a #37 o-ring, Buna-N, 70 durometer, per the definitive treatment of this topic by tencentlife on this forum: http://www.shoptalkforums.com/viewtopic ... t&start=30

I used a 1/16 parting tool in my lathe to cut the groove, after studying a number of sites about o-ring design. http://www.sealanddesign.com/page/o-ring-groove-design

[Crawdad]

There was one minor defect with the CB pump: somehow the idler shaft was a bit marred, as though it had been knocking around in a bag of loose parts, out on a bender when nobody was looking. To their credit, CB offered to sell me a whole new pump at cost (about half price), but since I have so much time in this pump, that's the last thing I wanted. Any sane person would have let it slide, but I went ahead and made a new idler shaft.

[Crawdad]

The CB dry sump pump has a lot of room for improvement. The internal passages through which the oil gets from the suction stack to the pressure stack, and from the pressure stack back through the inner pump body to the main oil gallery, are both small and convoluted. The good news is that in many of these areas there is enough meat that they can be enlarged. It's just a matter of looking carefully to see where the various passages mate, and in what direction they can be enlarged without breaking through. So you end up with a lot of irregular shapes; very few of the holes were still round when I was done.

[Crawdad]

Of course you also need to do the basic pump blue-printing, best described (with pictures) by Bill Fisher in his classic How to Hot-Rod VW Engines. This pic is pretty ugly, because it's hard to use the very tip of a burr, down inside a recess. I used a Dremel to extend the floor of the inlet passage all the way to the "root" of the suction gears, to maximize gear-filling. I also enlarged the inlet port and eased the transition to the floor area.

[Crawdad]

This might be a little controversial. I added a second port to the pressure side of the pump. To get from the pressure stack to the main oil gallery, the oil has to make a bunch of 90 degree turns. What I did was simply add an alternative path, a parallel circuit IN ADDITION to the existing one. It taps directly off the area where the pressure gears fling their oil, through a 3/8 external line, and into the main gallery through the hole where a full-flow system is normally plumbed. I expect having a second path will reduce pumping losses; I don't expect it to have any effect on the volume of oil flowed. It might help pressure a bit. The size and RPM of the gears determines flow, I am merely reducing the amount of power it takes to generate that flow. The ratio of scavenge flow to pressure flow is also preserved, since that is simply a function of the relative sizes of the two gear sets.

The real trick was figuring out what kind of fittings and oil line would minimize the packaging problem. There is no really elegant way to plumb it, because the inlet and outlet are so close to one another. Fittings take up a lot of space! And hose can't turn a sharp radius without collapsing. So I used a hard line of 3/8 copper-nickel alloy; it is sold as transmission cooler line in auto parts stores. Here it is in its rough configuration. It stays well away from the exhaust. I flared it with a cheap HFT flare tool. It turns out the AN standard (37 degree single- flare) is identical to the JIS standard that plumbers use for gas lines, so I went to the hardware store and was able to handle a bunch of different fittings to see what would work. I'll be keeping a close eye on it to look for leaks; the main worry is metal fatigue at the fitting. There shouldn't be any relative motion, and copper is fairly malleable, so I'm hopeful.

[Crawdad]

Lapping the pump body and gears on a thick piece of glass with wet-and-dry sandpaper flooded with solvent, to get zero end-clearance. End clearance will then be set by the super-thin gasket. I needed to de-burr the gear teeth after this operation.