Thought the following would be helpful for those contemplating this. I have before and after pix on my web site. One comment on engine temps: As you will see, my O235 was running way too hot. You will want Lyc temps to always be below 400 F (downdraft cooling as measured at the bayonettes--------make corrections as documented on many sites about updraft cooling)
Longez 0320 Mod
I recently switched out my dead 0235-L2C for an 0320-EXP. December 2001, I heard funny noises coming from my engine (sounded like a rattling exhaust pipe) just after I got airborne. The number 4 cylinder was getting real hot so I throttled back and stopped my climb at about 1500 ft which let the cylinder cool off. I let myself get away from the traffic pattern (always a big mistake) and decided to climb since I did not like being away from the airport at such a low altitude. Right after I added power the engine made lots of noise like a car when it loses a muffler on the highway. At the same time was a strong oil odor. At this point I was about 5 nm from Camarillo (my home airfield) but a little closer to Santa Paula which is a small and tricky runway to get into. I throttled back to idle and after about a 5 second hesitation of pointing halfway between Camarillo and Santa Paula, I turned toward Camarillo and declared an emergency. I saved the nose gear until I absolutely had the runway made and even had to use the speed brake and deployed rudders to land----boy the Longez can sure glide.
The number 4 cylinder had a hole in it and actually torched my cowl a little bit. I pulled the cylinder and found enough cam wear to warrant splitting the case. With well over a thousand hours on the engine, I decided to replace the whole engine.
New engine issues:
-Want Bigger. I was never satisfied with my 0235. I only flew at 120 kts, the climb rate was only 500 fpm or so and getting out of short fields was sometimes difficult. Lycon of California built my new engine and took my 0235 core ($3,500) as part of the deal. They put on NFS custom forged 10.1 compression pistons; port, polish, and flow balanced the cylinders. I stayed with a carburetor and mags due to trying to stay within a budget (but not convinced this was a good budget decision).
-Engine Mount.
I knew that I needed to beef up the engine mount, but I did not know how. I contacted Dave Ronneburg at Renaissance and asked if he could help. He told me to bring my mount in and he would beef it up. Basically, two new support arms were added to the upper two biscuits (one support arm for each).
-Engine Mount extrusions.
I talked to many people about the engine mount extrusions. I found three camps of people. The right way appears to be to change out all four extrusions and replace them with ones that have a ½ inch longer vertical web. Others said don’t do anything. The third group said to only worry about the upper extrusions. I decided to only worry about the upper extrusions. Like I said, the right way is probably to change out all four but the lower ones are going to be a lot of work. However, if you are going to change out the lower extrusions, this would be a great time to make a common fuel sump since you are going to have to cut the original sumps off to get at the extrusions.
The bolt heads of the engine mount extrusions are underneath the skin of the outer fuselage. I used a stud finder (the cheap magnet kind) to find and mark the bolt heads. I then used a drill to dig into the skin so I could put a rachet on the bolt heads. Removing the bolts was fairly easy, but I had to use a sledge hammer to coax the extrusions out. Make sure you use a dremel to carefully remove any material that may be in the way of driving out the extrusion (don’t damage the spar!).
Boeing engineer and Varieze driver Joe Person gave me detailed directions on how to match drill the extrusions. You want the bolts to fit exactly with no slop. This is what Joe sent me (thanks Joe for your help----I really appreciate it!).
“What you make is a jig block out of ¾ inch particle board (or something similar). Straight and flat wood-I prefer particle board for easy drilling, and you can often get 2 by 4 foot sections at many large home improvement retailers). Screw & glue the pieces together (use a piece of new extrusion to make sure both extrusion faces nest against the jig, in full contact).
Take an existing extrusion, nest it into the jig block, and install some sort of “stop” on one end of the jig block (a clamped small piece of wood works). This sets the fore/aft position of the extrusion. With the extrusion against the stop, drill back through the jig block at the 4 holes in the extrusion (at the holes that are common to the c-section spar and the upper longeron). Enlarge these holes (to about ¾ inch, or more if necessary) in the jig block so that a precision drill bushing will sit down inside the big hole, and touch the extrusion. The sketch shows the basic detail at two of the four holes in the set-up-the “horizontal” holes in the jig and the extrusion are done in the same manner with drill bushings and large holes in the jig block.
Once you have the 4 holes oversized, clamp the existing extrusion back into the jig block, mix up some Bondo, and , with long-enough ¼ inch bolts (better yet, use a ¼ inch drill bit for the alignment-it’s more accurate), Bondo the drill bushings into the large holes in the jig block, It is likely that the holes in the existing extrusions are “sloppy”-do your best to “average out” the long axis of the ¼ inch bolt/bit, with respect to the hole (the bolt/bit will wobble in the hole in the extrusion-center the bolt/bit in the “wobble boundary” as best you can before the Bondo cures. You could, with help, find the approximate “center” of the wobble, and get a helper to tack the bushing in place with super glue & backing soda, prior to Bondo application). After the Bondo cures in all 4 locations, pop the existing extrusion off, clamp in a new extrusion, and drill away. Do this process for each extrusion.”
-Engine Install.
Two big hints here. Number one, when you try to put the engine on to the mount, you will have a much easier time if the nose gear is extended. Number two, make sure you have the little oil pressure fitting in place before you put the engine on the mount. I discovered this the hard way and had to bring the engine hoist back over, get the weight off the mount, loosen the 4 bolts, and tilt the engine back so I could get the fitting in.
-Brake Master Cylinders.
One bad thing with the 0320 with mags----the original master cylinders don’t fit-------well, actually they do, but they are touching (not good). Hal Hunt did some welding on my rudder pedals so that I could move the master cylinders up by my feet. It was a little more of a challenge since I have a short nose.
-Engine Heat.
I always had heat issues with the old engine. Temps would climb to 450F in a climb and stabilize at 435F for cruise---and with updraft cooling, the temps are actually worse than the readings. I wanted to be in the 325 to 375F region for cruise. Oil cooling was never a problem. I did make a channel to give some spot cooling to the number 4 cylinder, but I am convinced that spot cooling is bad for an engine (in my case, I think that I was just cooling off the thermocouple). I decided that I wanted to go to down draft cooling. Down draft cooling is more “normal”, Lycoming engine temps are based on down draft cooling, the air is direct and does not need to make a 90 degree bend to get to the cylinder. Also, there was no way I was going to spend a small fortune on an engine and go back to the same cooling scheme that I had. The other thing that I liked about down draft cooling was that the baffling is so much simpler to make. Basically, the bottom half of the engine does not have to be walled off. You don’t have to build complicated shapes to get around the starter, alternator, oil cooler (mine is on the back), and lower cowl. I borrowed lot of baffling ideas from a lot of different aircraft but used the Berkut for most of my ideas. In particular from the Berkut, is that I used a nice flat piece of metal all across the back of the engine and used “shelves” to fill in the gaps made by the cylinder contours. The original Longeze “back wall” has many bends all over the place and is pretty complicated to build. Like most down draft cooling machines, I have no inter-cylinder baffles on the upper side of the engine. The lower inter-cylinder baffles are the standard set that came with the engine.
The bad news in this whole evolution was that I had to build scoops for the upper cowl. George Shell has some great pictures of his scoops on the internet. The only difference with my upper cowl from his was that I built in an oil door. Like George Shell, I closed off the Naca scoop and have connections for carb ram air, oil cooling, alternator cooling, and mag/vacuum pump cooling.
Accessories and Stuff.
-Hal Hunt 4 in/4 out pipes
-Hal Hunt ram air box
-Vacuum pump from my old engine
-B&C 90 degree oil filter adapter from my old engine
-Oil cooler from my old engine
-Nipon Denso alternator from my old engine
-EI Engine Monitor (4 CHT, 4EGT, and MP)
-Electric primer (guarded switch turns on fuel pump and opens solenoid to prime cyls)
Throttle/Mixture Cables.
I spent a couple of weekends trying to hook up the throttle/mixture cables. The trouble that I was having was that the “bike” pull cables did not have the authority to move the throttle or mixture cables without using some hefty springs. With my 0235, I did not have to overpower an accelerator pump. If something happened to the springs on my 0320 in flight, I would be in real trouble. I abandoned this approach and installed push-pull cables. I ended up having to dremel off the top of the front and rear cockpit armrests to get at everything. If I did this again, I would remove the whole front left armrest and reglass it when done.
I used a throttle/mixture arm support for the 0320 engine that Vans aircraft sells. I had to remove a little material from their bracket to get it to work for me and I had to bend the mixture tab to a slightly different angle.
Marking the opening in the firewall for the throttle and mixture cables to pass through was kind of tricky. I used a scrap piece of throttle cable to feed from the carburetor throttle arm through the bracket to the firewall. I marked the firewall where the cable hit and drilled through it. Keep the number of cable bends to a minimum. Don’t make sharp bends. I also used a small squirt of graphite inside the control cable sheath.
Ram Air Box.
Hal Hunt builds a great ram air box. I had to remove some material from the throttle/mixture support bracket so that the carb heat hose would not rub on the bracket. Also, my lower cowl would not fit with the new ram air box. Hal Hunt gives great directions on how to remedy this kind of situation. One is really easy and involves letting the carb sit deeper in the box. The second solution is to let the box sit in at an angle, and the third and most hard solution is to recontour the cowl. Of course I picked the harder route and recontoured the cowl. I had other issues than the carb air box such as the intake tubes. I also extended the inlet of the ram air box to a slip joint on the walled off NACA scoop.
Lower Cowl
I cut a hole large enough in the lower cowl for the ram air box to fit through. I then attached it to the aircraft. I then took gray tape and taped over the hole which gave me the general shape of the ram air box (boy did it leave a big bump!). I then carefully took off the cowl and set it into a chair with arms bottom side down (did not want the bump to be pressed in by the seat bottom). I then filled up the bump with a can of pour foam and let it sit overnight. The pour foam puffed out the gray tape a little more which was good. I took off the tape and put new/neater tape job on. I dammed up the sides of the cowl and put several cans of pour foam in to give my a new cowl shape. I used a butcher knife to get me a good shape. The job of the gray tape on the bump was to let me know when I was getting too close to the ram air box with my butcher knife. The lower cowl is kind of boat-tailish but does not come to a point. Instead, it is open to just let the air flow through. I have a rather large opening in the back of the plane (cooling is my number one concern).
