Squishy, dry-sumped 2276 build thread

[Crawdad]

I got my cam gear plated with an "electroless" nickel process, to take up some of the gear lash. (Unlike standard electroplating, this is a process that can deposit metal very precisely.) The results are ambiguous, due to a lack of concentricity between the cam gear's outer diameter and the recess in the flange that locates it on the cam. Anyone interested can read along in this separate thread:
http://www.shoptalkforums.com/viewtopic ... 5&t=149848

[Clatter]

Love the build so far. Keep going!

And, no, you cannot pay someone to love your motor like you love it yourself.

I somehow feel that correcting the deck is better practice than shortening cylinders.
Might just be that it will be me that forgets their different lengths at a tear-down years from now.
More idiot proof, I guess..

Considered the HVX mods to oiling?
http://bobhooversblog.blogspot.com/2007 ... -mods.html

Also like to port the case internally to reduce 'pumping losses';
Especially with counterweights hindering the pressure from moving around in there..
http://johnmaherracing.com/tech-talk/in ... fications/

[Crawdad]

Removing the oil gallery plugs (with a slide hammer), drilling them, reaming them with tapered pipe reamers, and finally tapping them, required a bit of tooling. I'm glad I did it, because there was a fair amount of crud hidden in the galleries.
The best description I have found of exactly what needs to be done, and what you need to do it, is here: http://www.huelsmann.us/bugman/FilterTech.html

I drilled most of them with a hand drill, but the one near the upper left corner of the left case half passes VERY close to the distributor drive hole, so I used a drill press.

The drilling on the 3-4 side that connects the main oil gallery to the center cam bearing saddle (shown with the tap handle sticking out of it) was not drilled all the way through at the factory; it had a big hanging burr that was obstructing the passage about 30% and needed another 1/8 inch penetration. I found a flashlight is indispensable for tracing all the passages and seeing where they connect.

[Crawdad]

Clatter, thanks for the link to that article on case porting. That's the best write-up I have seen on that. Because I will be running a dry sump, and will also be using those magical Krank Vents, I hope to have pretty good vacuum in the case. So I figure the case porting is moot. Right? Very little oil, and not much air either. I read on one STF thread that it's a good idea to install the flywheel seal and sand seal backwards if you're running vacuum in the case, to prevent them from making a screeching noise.

As for the cylinders, I won't be shortening any of them. I am merely matching variations in their length as delivered (about 5 thou) to the variations in the case, which are also about 5 thou. So that works out well.

And yes, Hoover oiling mods are next!

[Crawdad]

HOOVER MODS
It took me a lot of head scratching and poking around the case, tracing every oil path, to finally understand the Hoover oiling mods. Maybe others have similar confusions, so I'll share what I learned. Have faith, it all makes sense! The first mystery solved was realizing that the oil gets to the 1/2 side by passing BEHIND the cam bearings, i.e., in the groove in the cam bearing saddle. But it does so only at ONE of the cam bearing saddles; you want it to do so at both of them, and that requires some drilling.

Drilling the case to get more oil to the lifter bores on the 1/2 side (and via them, to the 1/2 head) was a delicate operation. You are extending the holes that run through the lifter bores on that side so they meet up with another hole that you drill down through the cam bearing saddle. It is that latter hole that is the delicate one, because the case terminates just beyond where you want the hole to end, and you don't want to break through the case. Therefore, extend the lifter bore hole FIRST and leave the drill bit in the new hole. That way when you break through to the first hole with the second hole, you will hit the drill bit. This is good for two reasons: the bit will move, alerting you that you are deep enough, and the bit will also protect you from going deeper into the case. The bit you need for extending the lifter bore oil passage is 15/64, 12 inches long (all the minor oil passages seem to be 15/64). The good news is that the existing holes (which you can access after pulling one of the tiny aluminum plugs on the flywheel side of the case) serve as a perfect jig for making sure your new hole is perfectly in line with them, centered on the lifter bore.

[Crawdad]

I cut three diagonal grooves, 60 degrees apart, around the circumference of the lifters, per Bob Hoover (RIP). I think a good way to describe this is that you are increasing the "oiling dwell" to the heads. The grooved/non-grooved areas of the lifter serve as a valve. Only one of the grooves feeds oil to the pushrod, via the hole on the shank of the lifter. By connecting the two grooves, you are recruiting a larger area of lifter travel to serve as a "valve open" condition. Of course, you can't get something for nothing. The lifters themselves will have less oil pressure in their bores. Right? And of course, everything up stream of the modification (main, rod and cam bearings) will have less oil pressure too. But I gather this is thought to be a worthwhile tradeoff for getting more oil to the heads.

I tried a few different techniques for grooving the lifters, practicing on some old ones. I got the cleanest cuts, and fastest, using an angle grinder with a cutoff wheel. I thought I was going to have to deburr 24 grooves, but this technique left no raised burs to mar the lifter bores.

[Ol'fogasaurus]

Don't forget to polish the notches also. No stress risers on the sides and corners of the notches.

[Crawdad]

Ol'fogey, I hadn't heard of that being necessary before. Do you think there is much stress in this area? Do lifters sometimes break on their shanks? All the spring pressure is bearing down on the center of the lifter (via the pushrod), while the shank merely slides along the lifter bore. But I'm open to being corrected here. I've got a set where some of the heads have worn so thin that chunks have broken off along the perimeter of the head.

[Crawdad]

As most of you know, Bob Hoover's oiling recipe includes modifying the rockers by adding grooves in their bushings, to connect the oil-in hole (from the pushrod) to the oil-out hole (to the adjuster screw). But with CB's 1.4 ratio rockers, with the adjuster on the pushrod, I can see no analogous mod to make. I suppose you could try drilling through the casting and bushing on the valve side, in the hope of getting oil to spray on the lash caps, but the odds of getting the oil where you actually want it seem slim, especially since the aim of the stream will vary with oil pressure.

But there is one area where I wonder if the 1.4 rockers could be improved for oiling, and that is the adjuster screw. The oil-in hole is about the same as the pushrod's hole, but the oil-out hole is really tiny. Does that express a considered judgment about how much oil is needed in those rocker bushings? Is it a matter of not wanting to weaken the screw with a bigger hole? Since the screw is captured by threads on either side of the hole, I don't see how spring pressure would be putting much stress on the center of the adjuster. Has anybody tried opening this hole up? After doing all the other Hoover oiling mods, it seems odd to leave this hole as the limiting factor for getting oil to the heads.

[UKLuke72]

If you want more oil up there you could drill the ends of the pushrods... That'd squirt oil radially towards the valves/springs etc.

[Crawdad]

That's an interesting thought, UKLuke. I've never heard of it being done. Presumably the pushrod rotates (at least, it is free to do so), so you'd have to put a series of holes around the perimeter of the pushrod. So at least half of the oil getting sprayed would end up just wasted on the valve covers. Also, these new holes would have to be beneath where the pushrod enters the adjuster screw cup, which would put them too low for their spray to reach the lash caps (though they might spray the valve springs). Or is it just a crazy chaos of flying oil in there, in which case the exact aim doesn't matter, and you just want more volume? In any case, it seems best to have the oil start by lubing the rocker bushings, and in that case the size of the hole in the adjuster screw is pretty critical. I'm just a little uncertain if bigger is necessarily better.

[Crawdad]

Speaking of lifters, I am using Scat Lube-a-Lobe. I chose them because normally the cam lobes are splash-lubricated, but with a dry sump system there will be very little oil in the sump, so the .024 oiling hole in the face of the lifter is a welcome touch.

[Crawdad]

I used the split-difference method for establishing TDC. The way I would explain it is that the piston has some non-zero dwell at TDC while the crank continues to rotate, so you can't rely simply on your indicator maxing out at some value. That leaves you guessing where the center of that dwell occurs. So you measure at what point in the crank rotation the piston is at some (arbitrary) point BEFORE TDC, and then again at that same distance (say .050) AFTER TDC. Take the difference in the number of degrees of crank rotation, divide in half, add to the first value, and that is true TDC.

I like this enormous degree wheel; it gives you very fine resolution.

[Crawdad]

I found I was assembling and disassembling the bottom end repeatedly while mocking everything up, so I made this flywheel-side TDC marker, indexed to the flywheel. Unlike the degree wheel on the pulley end, it stays in place when I split the case, so I don't have to re-establish TDC every time I split the case. When I reassemble the case, I simply put my flywheel mark at the arrow, then zero my degree wheel to the wire pointer.

[Crawdad]

All four cylinders (AA brand) required clearancing for the 10mm head studs.

All the barrel shims require deburring. Once deburred, my .010 (nominal) shims measured .012.