KIT ENGINES PART III

At present, I think there is now a shortage of reasonably priced small stationary engines that meet the the reliability and longevity requirements of our farmers. I've had a few conversations with Farmers that swear the gasoline engines are costing 4 times as much to run as their old reliable slower speed diesels, and they need far more care. I'd be very surprised if these so called legal engines didn't actually pollute more than some of the engines they are replacing.

We should all look to the EPA to publish a list of certified engines we can burn Biodiesel in. We know they will not please everyone, but why they force us to certify an engine on a fuel we have no interest in burning is curious. When we consider all those in our government who solicit our vote, and do little to promote one of the most viable alternative fuels, I take note.

There are still those who believe that burning SVO as a fuel is not a viable solution, all too many in our community have already proven that's not the case. It appears the EPA has banned one of our Favorite SVO hobby/research engines here in the USA.

With all that said here's another installment from a respected experimenter who uses his engine to further his understanding of Alternative fuels, and how we might burn them with efficiency and low emissions. Thanks for all you do for our community Quinn!

George B.

Gentlemen,

Now that the holidays are over and the kids are back in school and I have some time again for play, here is the continuation of the last report I sent you. Feel free to use or not use any or all of this however you like.

Quinn

-------------------------------------------------------------

Beta Test, Part III

These progress reports are now being read by a broader audience than I had anticipated when I first received the Beta Test engine and started to assemble it, so a few introductory comments are appropriate.

These engines were designed in a simpler time, and made to do a simple task well and without much fuss when maintained by people who used it as a tool to help them get their work done. Whether generating electricity for an estate, running a sheep shearing station or pumping water for irrigation, the Lister and its descendant, the Listeroid are made to do serious work. They are heavily built of low-tech materials, not particularly powerful, and very slow by today’s standards. They were never machined to especially tight tolerances such as are demanded by high speed engines that might develop 10 times more power in each cylinder than the lowly 6/1 produces in its single cylinder, and that makes them forgiving and easy to work on..

However, throw into that mix the fact that Listeroids are manufactured in a Third World country by mostly unskilled labor in job shops that seem to have no concept of quality control, and problems can and do arise. And there is some indication that even in India, these engines are being phased out as rural electrification, co-ops, and government programs reduce the need for them, even as improvements in combustion technology render them technologically incapable of meeting ever more stringent environmental regulations.

Many of these engines will probably run well right out of the box. This one did. None of the problems I’ve documented would have prevented the engine from running for a long time. However many of us aren’t happy with “good enough.” I’ve always had a tendency to want to take a boat, or tool, or motorcycle, or engine and tune it or tweak it or rebuild it even when it didn’t need doing, just because that’s I enjoy doing so. Unlike others you might read about who live off-grid and who rely on their gensets to keep their batteries charged, lights burning, or water pumping, that’s not my situation at present. I’m more interested in exploring this engine, cleaning and polishing and painting and tweaking where I can. When I get done, it still won’t be a Swiss watch, but it will be better than it was when I got it, it will run better and for longer before needing attention, What’s most important to me is that I will know a lot more about it than when I began this adventure.

My purpose in writing this is to document with words and photographs what I found during a complete teardown and rebuild of a PS 6/1 kit engine. If it can help anyone to fix something that’s wrong with their engine, or if these pages can help familiarize a new owner with what’s going on inside their engine, I consider that my time was well spent.

So think of this as another installment of Quinn’s Adventures in Reassembling/Tweaking a Cool Old-Looking Hunk of Iron (Just Because I Can).

Parts Cleaning and Inspection

Disassembling an engine provides one with an unsurpassed opportunity to evaluate the quality of the fit and finish of the parts, and the care with which they were assembled. It also makes cleaning and detailing the parts much easier.

The underside of the piston in the Beta Test engine appeared to have some grit embedded in the metal surface, however scraping with a steel pick and application of duct tape didn’t remove anything except a slight amount of surface dirt. However I didn’t like the texture. It just LOOKED gritty. So I decided to sand blast the underside of the piston using a cheap hopper-fed sand blaster purchased from Harbor Freight for $20. The unit worked fine for this application and when I was finished the metal surface was a uniform gray color and I was picking sand out of my ears and my hair for a couple of days afterward. I then washed the grit out of the surfaces of the piston with hot soapy water and a bottle brush followed by a soak in detergent solution in an industrial ultrasonic bath. Finally, I rinsed the piston with hot water and a scrub brush and dried it in a forced air oven at 120 deg. F. Then I coated it with WD-40 and sealed it in a new zip-lock plastic bag. While I was at it, I cleaned the inside of the piston wrist pin with a test tube brush and detergent solution. My other 6/1 came with the pin packed with grit.

Figure 1. The underside of the piston looked dirtier than it was. After sandblasting, the metal surface was a uniform light silver-gray color.

Cylinder Liner Projection

A commonly reported problem with these engines is blown cylinder head gaskets, which is caused by too much cylinder liner protrusion. As I mentioned in Part II, the cylinder liner protruded above the cylinder casting 0.030”. India recommends no more than 0.010” but if you think about it, the original Lister engines were sleeveless, so the top of the cylinder bore was flush with the top of the cylinder, so maybe even 0.010” is unnecessary.

The cylinder liner on the Beta engine needed to be lowered about 0.020” relative to the cylinder deck. I thought I might accomplish that any of three ways:

1. The simplest approach would be to get a piece of 0.020” brass and tap out a shim that would lie beneath the head gasket. That would reduce the overall protrusion to 0.010”.

2. Ask one of the custom gasket makers on the internet to make a shim using an old head gasket as a template.

3. The last and the most difficult approach to the problem would be to turn 0.020” off of the locating shoulder on the cylinder liner, which is what I did.

I was unable to locate an auto machine shop that was staffed by anyone who spoke English. Seems everyone doing this work is from Pakistan or Waziristan or Mexico these days. So rather than take the chance that a miscommunication might put me in worse shape than I already was, I made a present of a few carbide cutters to a friend who is rather reluctant to work on ferrous metal in his shop and convinced him that, for the good of the Listeroid community, this operation NEEDED to be documented.

We first machined a piece of birch to slip into the end of the cylinder for the live center. The 3-jaw chuck engaged the other end, and after a few adjustments we were making chips. I verified the hardness of the cylinder first by running a mill file across it. The file cut the metal, though not enthusiastically, so while the metal was hard, it was not harder than a file so it should be machinable. The cut proceeded very slowly and required a lot of pressure on the feed and plenty of Cool Tool in the cut, but we eventually turned 0.021” from the shoulder which can be seen in the background of the picture below.

Figure 2. The locating shoulder on the cylinder liner was turned down 0.021" on a lathe using a new carbide cutter. The birch plug in the open end of the cylinder allowed a live center to hold the free end of the cylinder.

I test fit the liner in the casting and measured the liner projection as 0.009”. If I were faced with this problem again, I’d make a brass shim or two. It’s much faster and easier than any machining operation.

Checking the Piston

Next, I wanted to make sure that the piston was as well machined as it appeared to be. I earlier had trouble getting consistent readings using a dial caliper, so I ordered a cheap magnetic base and a dial indicator from Harbor Freight, and another base and dial test indicator from Enco. The dial indicator reads the position of a spring-loaded pin that registers the position of surfaces directly beneath the dial. It is best suited to applications in which you have direct access to the surface to be measured. Most inexpensive dial indicators read with a precision of 0.001” which is adequate for most needs.

Figure 3. An inexpensive dial indicator mounted on a magnetic base makes easy work of measuring surfaces that you can access directly.

In many cases, gaining direct access to a surface is not possible and a dial test indicator is preferred. Unlike the dial indicator, the dial test indicator reads the position of a spring-loaded wand, and if the offerings in the catalogs are any indication, the dial test indicator seems to read with greater precision, usually to at least 0.0005”.

Figure 4. A dial test indicator measures surfaces that can't be accessed directly.

I used the dial test indicator to determine whether the cylinder casting top and bottom surfaces were parallel by placing the casting on an oiled ground cast iron surface (table saw table) and rotating the casting so the indicator wand ran around the perimeter of the four sides of the cylinder casting. It turned out that the casting surfaces were parallel to the deck within 0.002” which is, in the immortal words of my 7^th grade woodshop teacher, “…good enough for who it’s for.”

Next, I wanted to determine whether the wrist pin was parallel to the piston skirt. I placed the piston on the oiled table saw table and indicated off the bottom of the wrist pin hole, (A in the drawing below). Then I rotated the piston and indicated off the same surface on the other side. The numbers matched to 0.001”. So far, so good.

Figure 5. Measuring the height of both sides of the piston.

Next I wanted to know whether the piston rings were parallel to the skirt, so I indicated on each of them in turn while rotating the piston slowly. The readings indicated that the rings were parallel to the bottom of the piston. That’s two out of three.

Finally I indicated off the top of the piston as shown in the Fig. 3 and was surprised to find more than 0.008” variation. The high spot was found near the intake valve side of the piston, and a low spot was found opposite that point.

I can just hear some people clucking their tongues in disappointment that the top of the piston could be that far off. But that figure needs to be kept in perspective. 0.008” is the thickness of two sheets of copy paper. It’s next to nothing in a low horsepower slow speed engine like this one.

The Mystery of the Folded Yellow Shim Revealed

After thinking about the piston for a minute, the REAL purpose for the folded yellow shim discovered in Part II became clear. And furthermore, its existence is evidence that the assembler was not simply bolting parts together willy-nilly. Rather, there is actually some QC in operation in Rajkot. In order to take the measurement necessary to determine that a shim was needed, a head was temporarily bolted into place to ensure that the subassembly was set up correctly. If that is what happened, the assembler and his employer deserve a kind word or two since the subassembly was shipped without a head, and they could have hardly been faulted if they should say, “Not my yob.”

Since the top of the piston wasn’t parallel to the top of the cylinder, the engine assembler got two different measurements when he checked the clearance between the top of the piston and the cylinder head. Assuming the top of the piston was dead square to the bore, he placed a folded shim to raise one side of the cylinder and head to equalize the piston/head clearance, not knowing that in so doing, he was actually causing the piston to tilt in the bore at a slight angle. A piston running at an angle to the cylinder bore might indicate misalignment by scuff marks on one side of the piston skirt, and would likely wear on the wrist pin as the piston racks back and forth with each stroke.

Recall that when I checked the parallelism of the piston with the top of the cylinder earlier in Part I, I found the top of the piston parallel to a straight edge laid across the top of the cylinder liner. I looked no further, because that is what I expected to see. In retrospect, I should have checked UNDER the cylinder! And while I was at it, I should have checked the parallelism of the crankshaft and the machined top surface of the crankcase that the cylinder casting sits on.

And while I was doing that I should have checked that the top deck was at right angles to the machined surfaces that the bearing caps engage and …and… It has to end somewhere, and since I don’t have all the tools to check everything with a high degree of precision, I measured what I could and kept my eyes open for signs that any other surfaces might not be true. For instance, I laid a good rafter square across the top deck and checked that both sides of the crankcase were at right angles to the top. Within the limit of precision of the square, they were spot on. However Jack Belk described the use of a precision mechanic’s spirit level that can be used to level the case, then level the crankshaft, then level the cylinder and by use of precision ground setup blocks, level the piston. Since I don’t have such a level (less than $100 on eBay), and would probably never have use for one again, I chose not to go there.

“Science has achieved some wonderful things of course, but I'd far rather be happy than right any day."

-- Slartybartfast, The Hitchhiker’s Guide to the Galaxy.

It doesn’t take much time to check some of these details, and while this engine might have run a long time just as it was out of the crate, a little time spent making sure everything is right might save many hours of downtime later.

Surface Preparation, Priming and Painting

Since I had the engine completely stripped I decided I’d spend some time to get the surfaces as smooth as possible before painting. For this operation, gloves, eye and ear protection, a dust mask and an apron are required. I used a $20 4.5” angle grinder available from Harbor Freight to do most of the grinding. 80 and 120 grit aluminum oxide grinding wheels did a wonderful job of removing the acne scars and orange peel texture of the cast iron on the crankcase, cylinder casting and head. I found that a light application of the grinder was all that was necessary to cut through the pockmarks revealing a smooth layer of bright cast iron beneath. The color of the iron used in these engines is surprisingly white, not like the standard grey iron that is used in most engine castings that I have seen.

Once the grinder had removed most of the surface blemishes, I changed to 60 grit aluminum oxide or zirconium flap sanding disks. These articulated sanding disks really make short work of the swirl marks left by the grinder and leave a brushed white metal finish that should hold paint well. Overall, I used only about half of one grinding disk and 5 flap disks on this project. A die grinder or Dremel tool with attachments can be great for accessing areas that are too small for the angle grinder.

When all the surfaces had been ground and sanded, I spent some time filling with Bondo the few defects in areas I couldn’t reach with the grinder. There were very few defects in the castings on this engine. Though the surface finish leaves something to be desired, those imperfections are no more than skin deep. I have to echo Jack Belk’s comment about the quality of the cast iron used in these castings. The quality of the metal used and the casting process appear to have been very good. No cracks, voids, inclusions or evidence of blowouts.

The next day I sanded once over lightly, removed the dust with a vacuum, then wiped with a clean rag and solvent to remove residual dust. Then I sprayed with fast drying gray auto primer. I’ve never liked spraying auto primer because the high talc content tends to clog spray tips and is difficult to clean up. Spraycan auto primer works fine for this application. As with any spray process, more thin coats are far better than fewer thick coats. Next day I sanded by hand using 180 grit aluminum oxide paper wrapped around a sponge, vacuumed the dust, wiped with paint thinner and a clean rag, then applied the first of three topcoats.

I ended up using Rustoleum Hammered Silver like I used on my Ashwamegh 6/1 a couple of years ago. Call it lack of imagination or maybe I just didn’t see any other colors in a spraycan that I liked better. Ferrari Red had been my first choice but I thought it might look too much like something out of a kid’s storybook if it were painted that color. And everyone seems to have a green Listeroid, so that’s out. I’m going to have to live with this engine, and hammered silver has a nice industrial look that reflects light well and should be easy to work on in a confined space like a generator shed.

A word to the wise: Follow the directions on the can. Rustoleum Industrial Enamel specifies that everything should be sprayed within 2 hours, and then let dry for 48 hours before applying another coat. On the Smokstak.com website there are many horror stories about paint that never dries told by folks who re-coated without waiting the full 48 hours. And remember that just about any oil based paint will work fine on diesel engines. Diesel fuel and lubricating oils don’t soften paint like gasoline does, though if you’re into Bio-Diesel, depending on how well you neutralize the residual methoxide (you DO bubble wash, don’t you?) you might have some residual sodium hydroxide and methanol, both of which are effective paint strippers.

Engine Reassembly

After all the parts had been thoroughly cleaned, ground, filled where necessary, primed and painted, it was time to begin reassembly. I stowed all the paint-related paraphernalia, burned the rags in the fireplace (fire-starters) and got out the wrenches.

The first step was to install the camshaft and valve lifter guides. I installed the lifters and guides and held them in place while I slid the camshaft into its bushing which I had lubed with STP Oil Treatment, a viscous honey-like goo that works great as an assembly lube because it is very sticky and won’t run out of assembled parts like plain motor oil will. At this point, the cylinder is sitting on top of the crankcase in order to minimize dust that might fall into the crankcase. The cylinder hold-down studs have yet to be installed.

Figure 6. First step in reassembly is to reinstall the camshaft, tappet guides and lifters.

The tappet guide hold down clamp and the exhaust valve compression release were installed next. This is a good time to go around the crankcase and install all the studs. I used a drop of blue Loctite to ensure that the studs stay in place. Doubled nuts allow you to seat the studs firmly without damaging the threads. The head studs were installed with RTV silicone gasket sealer, the idea being to keep any coolant that finds its way into the stud holes past the head gasket from leaking into the crankcase.

I had earlier pre-coated all the paper gaskets with a thin layer of RTV silicone gasket sealer; the vinegary-smelling stuff, as George recommends in Listeroid Longevity. Coated paper gaskets are less likely to stick to metal surfaces and might be reused in the future.

Next, I installed the idler gear and shaft after first scraping paint away from the surface the machined shoulder registers against.

Figure 7. The cam gear and idler are engaged. Note the painted governor flyweights.

The last time I did this, I found that you can get the valve timing right if you rotate the camshaft so the fuel injector lobe is pointing to 11:00 when the piston is at TDC, at which point the keyway on the crankshaft will be at 6:00. When I try to start up, we’ll see if my memory serves me.

And in case you’re wondering, yes, I painted the governor counterweights. When I examined the governor assembly carefully I found that the weights had some surface grit that had to go. So I removed the weights and cleaned them with a wire wheel on my bench grinder. By then they were so clean and shiny I know I would have regretted it if I hadn’t painted them. The counterweights, by the way, had marks indicating that someone had balanced them (another indication of QC at the assembler!). When I checked, I found they weighed within a gram of each other.

Figure 8. Reinstalling the thrust washer and collar on the end of the camshaft. Tapered pins don't need to be peened.

Next, the steel thrust washer and collar were placed on the end of the camshaft and the tapered pin was tapped firmly into place. If the parts are assembled dry there is no reason to peen the ends of the pin. Friction will hold it in place.

Figure 9. Jack Belk documented this neat mod that he used on his first engine. A pin made from drill rod (or a framing nail) is pressed into the camshaft end oil hole cap and sealed with JB Weld (epoxy putty). Any oil intercepted by the rod should follow the pin into the oiling hole.

There isn’t much provision for oiling the left side of the camshaft. The steel bushing the end of the camshaft rides in has a hole in it that is directly below a hole in the top deck that we are supposed to squirt some oil in each time we start the engine. If you’re like me, you might not remember to oil the camshaft. I drilled a hole in the end of the camshaft oiling hole plug and pressed in a section cut from a 16D nail. The nail is held in place using JB Weld, a thickened epoxy that I’ve found to be very durable. The idea is that oil that gets splashed on the rod will dribble into the camshaft oiling hole. Thanks to Jack Belk, whose idea I enthusiastically appropriated.

Shims? Don’t Need No Stinkin’ Shims!

Next, during preparation for installing the crankshaft I knew that I would need extra adjusting shims for the TRB holders. The crankshaft end play is adjusted by these shims. I took a new shim and traced its outline on a file folder. The paper measures appx. 0.010” thick. Once the shims are cut out and sealed they perform well for those times when a ready made shim isn’t available.

Figure 10. Surplus file folders can be used to make main bearing adjusting shims.

A piece of ½” copper water pipe chucked into a drill press can be sharpened by beveling the cut end with a file. Depending on whether you bevel the inside of the pipe with a round rat-tail file or the outside with your common file, or mill file, or your common run-of-the-mill file, you can make a ½” copper pipe cut either ½” or 5/8” holes. Once the sharp end has cut a circle into a backup piece of softwood, it works almost as well as a gasket punch with the drill press set to low speed..

Figure 11. A sharpened piece of copper water pipe can cut clean holes into gasket paper. 1/2" pipe can also cut 5/8" holes, depending on how it is sharpened.

The inside of the shim was cut out using a sharp utility knife. If you leave the fold of the file intact while you do the cutting, when you’re done you will have made two identical gaskets from a single folder.

Figure 12. Hold the backup board in place and after a few cuts the cutter and backup will work together, shearing through the gasket paper and leaving clean holes.

Once I had all the shims cut out, I sprayed them with dark colored flat spray paint to seal the fibers to discourage oil wicking. I didn’t use George’s floor wax trick like he advocates for sealing the fibers in the head gasket, but I expect that would work, too.

Figure 13. Finished adjusting shims after sealing with spray paint are stacked to give the required clearance. Shims are added or removed as necessary. Be sure to use the same number of shims on each side of the engine to keep the crankshaft centered in the casting.

The crankshaft was placed in the crankcase and several adjusting shims were placed on each side. When I first disassembled the engine, I found that the TRBs had been badly over tightened. The specifications in the various Listeroid manuals indicate that TRB engines should have between 0.005” and 0.010” of crankshaft end end play, which is adjusted by adding or removing the paper shims beneath the bearing caps. In the case of the Beta Test engine, 5 gaskets (appx. 0.050”) were required on each side, about 3 more than the engine was delivered with.

Figure 14. Checking crankshaft end runout with a magnetic base and dial indicator.

Once the bearing caps were in place and torqued to spec., the crankshaft end runout was measured by affixing a magnetic base to the crankshaft and indicating off the side of the crankcase. The magnetic base has a V configuration which allows it to grip securely on cylindrical surfaces like the crankshaft.

I chose an unfortunate angle to shoot the above picture. The photo distorts the geometry making it look like the indicator is not perpendicular to the side of the crankcase. When the crankshaft is set up correctly there is a clearly audible “clunk” sound as you pull back and forth on the crankshaft, and you can just see the horizontal movement of the crankshaft. This isn’t a critical setting. If you don’t have the indicator, just set the bearing caps so there is some crankshaft movement. When you’re done, the crankshaft should turn freely with almost no friction. There will be some noise generated by the TRBs, however that is to be expected.

Figure 15. Reassembling the piston to the connecting rod. For years I did this using needle nose pliers, or sharpened nails driven through sticks. Having the proper tool for the job makes tedious jobs more enjoyable.

The piston was assembled to the wrist pin and connecting rod using assembly lube, and the snap rings were installed. The connecting rod was then assembled to the crankshaft and the castle nuts were torqued to 60 ft. lbs. with two shims in place. I determined earlier using Plastigauge that the rod bearing clearance was 0.0025” set up this way.

Figure 16. Cylinder bore should be checked for residual rust or honing grit. If you don't see clear evidence that the cylinder was honed, now would be an excellent time to do that.

Next, I checked the cleanliness of the cylinder bore by spraying it with WD-40 and wiping vigorously with clean paper towels. The towels came away perfectly clean (no color change – if they had picked up any black residue that would have indicated residue from the honing operation hadn’t been cleaned up sufficiently) so no grit either from honing or surface rust had contaminated the cylinder bore.

I placed the rubber o-rings in their grooves and smeared liquid dishwashing soap over them and the surfaces inside the cylinder that they slide over. I inverted the cylinder and placed it on the bench and lowered the inverted cylinder casting over the liner. I leaned on the casting with probably 75 pounds of weight while twisting the casting before the o-rings slipped into place.

Figure 17. The head was placed on top of the newly installed cylinder and cinched down with a layer of waxed paper between them to seat the liner.

I smeared a thin film of RTV silicone gasket sealer over the ledge on the cylinder casting and the corresponding shoulder on the cylinder liner. To ensure that the liner was fully seated and that the sealant had a chance to cure I placed a piece of waxed paper over the cylinder and dropped the cylinder head in place, torquing the head nuts moderately. The cylinder head was left in place for 24 hours before proceeding. This step was probably unnecessary but I wanted to discourage any migration of coolant beneath the head gasket.

Figure 18. Injection pump linkage is a common source of trouble. Many people mistakenly blame poor governor speed regulation on everything BUT the linkage when all they needed to do was to make sure all the parts move freely.

I assembled the injection pump and attached the linkage. I suspect that a lot of the complaints about poor speed regulation in these engines stems from dirty or misaligned linkages, rather than from a faulty governor. As George illustrates on his website, the governor/injection pump linkage frequently binds on new engines because of alignment or paint issues. The linkage on this engine was very stiff; paint crept into places where it shouldn’t have been. That problem was taken care of during the stripping process, but as I reassembled the linkage I carefully checked that all the parts were aligned properly.

The fork in the center of the picture which actuates the injector rack was misaligned, causing the fuel rack to bind in the closed position. I adjusted the linkage by carefully bending the arm to which the fork is attached by about 1/8” toward the engine. Because of the geometry of the linkage in the picture above, note that the pin end of the fork must be free to move in and out of the hole in the end of the arm. Make sure any paint has been scraped away from these parts and that the parts are well greased. This is a place where a little time and care can be very rewarding in terms of governor performance.

Figure 19. The piston/head clearance is adjusted by adding or removing paper shims beneath the cylinder casting.

Next, I adjusted the piston/head clearance. To do that you place the cylinder over the piston/connecting rod, which has been attached to the crankshaft and torqued to spec. Leave the rings off the piston for now. The dimension is adjusted by adding or removing cylinder base shims.

Pieces of lead were placed on each side of the piston directly above the wrist pin. A new head gasket was applied and torqued to spec. The crankshaft was rotated across TDC a few times before the head was removed and the thickness of the lead pieces was measured. I removed one thick base gasket and added back a yellow 0.0075” shim before I settled on a value I liked. The lead measured 0.050” on the intake valve side and 0.058” on the exhaust valve side. As discussed earlier, I know the piston isn’t flat on top, but the wrist pin and rings are parallel to each other and perpendicular to the cylinder, so that anomaly doesn’t bother me (old-fashioned engine, low power, low speed, low criticality).

Figure 20. The ring end-gap can be measured by inserting a compression ring into the cylinder, making sure it is set to the same depth all around. A feeler gauge measures the gap betweent he ends of the ring. As rings wear that gap will widen.

Next, I removed the cylinder and placed a compression ring in the cylinder bore and measured the ring end gap. The gap measured 0.012” The spec. printed in the Jkson manual states “not less than 0.012”. I placed the rings on the piston staggered about 180 degrees apart, oiled the cylinder bore with STP and lowered the cylinder over the piston and rings.

I keep meaning to make a piston ring clamp but I never have. A simple piece of sheet steel or brass with a couple of big hose clamps would work fine. But I did the job again by squeezing the rings one at a time until the weight of the cylinder dropped the cylinder over the next ring. If you’re not quick you can end up with a few really good blood blisters on your fingertips. A piece of weed-whacker string can be wrapped around the ring, too, but it might be more trouble than it is worth. So far, I still have my finger tips.

Getting Your Head Straight

In Part I, I noted that I was not satisfied with the alignment of the rocker arms. Fortunately, this problem is easily understood and remedied using simple techniques and materials. George discusses this subject at length in the Utterpower CD.

The rocker arms are responsible for actuating the valves. They do that by reversing the direction of the motion imparted by the pushrods, but in so doing, the rocker pad that bears against the valve stem/lash cap travels along an arc. So there is always some side pressure exerted on the valve stems which results in wear and erosion of both the valve stems and the valve guides. In order to minimize wear it’s important to ensure that the force being applied on the valve stems has as little horizontal component as possible.

Flashback to Part I: Note the poor registration of the rocker arm pads on the top of the valve stems in this pre-run photo. The intake rocker (left) is about 0.050” off of the center of the stem, while the exhaust side is off a bit as well. (Can you blame me for wanting to repaint this engine?)

Figure 21. Note the poor registration of the rocker feet on the valve stems. Lash caps were removed to more clearly show the misalignment. This is an easy tweak.

In the picture above, both rocker arms need to be moved toward the viewer, but the holes in the rocker block for the hold down stud and the 5^th head stud only allow so much movement. A possible solution would be to enlarge the holes in the rocker block, but a simpler solution immediately becomes obvious when a square is held against the stud.

Figure 22. The rocker block hold down stud was installed at an angle which prevented the rocker block from being located properly.

The stud was set in the head casting about 5 degrees off square. I straightened the stud by gently tapping it near the base with a 32 oz. ball peen hammer, and then rechecked the square in the picture above.

Setting the Rocker Arm/Valve Stem Contact Point

The reason the rocker assembly setup is important can be seen in the following diagrams. In the drawing below when the pushrod is not being actuated, the rocker arm is about level and the valve is held closed by the valve spring. Note that the rocker foot contact is in the center of the valve stem.

When the pushrod rises, the rocker arm tilts and the contact area moves off center. The off-center application of downward force results in lateral forces on the valve stem which wear the valve guides.

They say all life is a compromise. So it is with rocker arm actuated valves. In order to minimize valve guide and stem wear, it is best to set the contact point so that it is just past center when at no lift, at dead center at mid lift of the valve, and just inside center at full lift. On this engine the total contact area is about 1/8" or so 1/16” past the center of the valve stem should be about right when the valve is closed.

The picture below shows the rockers loosely assembled. The pads are now registering closer to the middle of the valve stems, but they’re not quite where I’d like them to be. About another 0.050” should locate the contact point just past the center of the valve stem. That can be accomplished by enlarging the hole in the rocker block.

Figure 23. Loosely assembled rocker assembly shows that only a little more adjustment is needed. Did I forget to clean those lash caps on the wire wheel?

In the picture below I have aligned the intake rocker foot with the valve stem. Notice that a gap of about 0.050” has opened up between the rocker block and the intake rocker arm. 5/8” brass shim washers can be added to take up the space and should last forever.

Figure 24. Waiting for Fed Ex to deliver my brass shims for the rocker shaft . . .

Finally, all adjustments were made and telltale smears of Dykem Hi-Spot Blue wiped from the lash cap surfaces. The head is all set up and ready to torque down for good.

Figure 25. Dykem Hi-Spot Blue paste gives a good indication of where surfaces register against each other, but you can use a drop of paint or black grease, too. Note the paste gets everywhere and is difficult to remove.

The Beta Engine is now assembled and mostly torqued down. There are only a few things left to do, though making the flywheels look good and balancing will take some time. The next installment will describe cleaning up and balancing of the flywheels, gib key fitting, reconnection of the pressure lube oil system, startup and testing.

To be continued . . .

Quinn