A98Coupe Stuart As far as shelby motor experience, I have 2 blocks and 1 set of heads. Block # CSX58 and CSX#428, ( inthe works ) #58 was a machining problem with locations and bottom out holes, and the list goes on. A machine shop in Nebs gave me a list to correct problems.
Want to start here, an aluminum motor is a living breathing thing. The expansion rate is about .001" every time it hits operation temps. When cold it contracts the same numbers. Here's the problem, sealing a motor with a .002" expansion rate. This doesnot include movement of the heads, intake manifold, timing cover, waterpump, and
oil pan, ( most are steel ) I also have an aluminum one. If your
oil pan is aluminum the expansion rate is about the same as the block, No problem. You said you have a windage tray, I bet it's steel. Here's the problem, 2 different expandsion rates. If you where around in the early days of motors that had iron blocks and aluminum heads they all had leaks of coolant and
oil over time. In the early days the RTV was used to keep adjusting to the expansions and would loose grip to the 2 parts it seals. We where told to rough up the surfaces with #80 grit sand paper to give better bite and holding properties. It helped some. It took HOnda to come out with the gray rtv the seals and lasts a long, long time with sealing and holding. GM, Jeep, and Ford now use this RTV. Moving on,
Oil leaks on these motors can come from anywear and always leak at the lowest point of the motor. Timing cover leaks go along the oil rail and end up at the back of the oil pan. The 100% way to find ANY leak is with a dye and black light. The kit cost about $45.00 and works on all fluids in a car. Add to fluid and run for 5-15 minutes and look for the leak. You may have the bottom of the motor apart. 1 question is the bellhousing inside full of oil? And the Clutch wet ?? If yes rear main seal. If not but leaking down The block plate on the bell housing it could be gaskets for the windage tray to block and oil pan. I have been through this problem 3 times. Sandwich gaskets that go between block, tray, and pan if the surfaces are not 100% flat will leak over time and push the gaskets around. My 1st set where cork, and they need fluid to keep them sealing and not dry out. I used a spray sealer Hi-tac on all surfaces. It worked for a couple of years and then the leaks started. Found the gaskets pulled and holes where moving and leaks would come from bolt holes. I went to a 484 stroker kit, had to modify windage try to clear rotating parts. I went this time with RTV. It took 1.5 tubes for both sides of the windage tray for sealing. Most people DON'T follow directions for installing RTV. It needs clean surfaces and more important needs to setup up for 3-5 minutes before installing. It then needs 24 hours to seal up. Need to follow torque specs and no adjustments after installing. Rear main seal should be about 10-20 degrees off center and not have the ends even with the cap and block. I add a thin coat to hold the seal in place. I add thin coats the where the main cap goes into the block, both sides and surfaces. I rough up the machine surfaces with a #40 grit paper for small scratches. All surfaces need to be 100% clean. I have done this repair once inside the car and once on the motor stand. 7 years of auto cross and road racing and no leaks. I am not sure how easy it is to pull the pan in your car, ERA with lifting the motor give enough room. I did lose a valve cover gasket at the R&G in NEB. The gasket was 12 years old and thick cork. A small piece popped out and I had an oil fire. No damage to paint or car and it gave the track guys some practice,
.
I am thinking the oil level may be causing your leak and you don't have the correct level in the oil pan. Also is the car on flat ground or on a hill of angles drive way? I ran Canton system in my car and over fill the pan 1 quart because of autocross and the poor return of oil to the oil pan and pump. I also use a HVHP oil pump with 100# spring. My whole system has 13 quarts. I have and use a 3 quart accusump for keeping pressure up in long high "G" turns. It also is used for per oiling the motor before starting it. This works for me. At some tracks they will not allow dry sump systems.
Oil level was the check done? You measure from the oil pan bottom with the pan in place to the block skirt, this is with all gaskets and seals installed. Remove pan. measure with windage tray on block to bottom of tray. should be about 1-2" I like the oil level right on the bottom of the windage tray. The measurement is in the middle of the oil pan. Subtract this from the total depth and you have your oil level. I mark the side of the oil pan and fill with water to get the correct amount of oil for this pan setup. If you are running a FE orginial windage tray which is solid steel, drill some 1/4" holes to help with oil draining faster into the pan. Holes be 1" apart at the lowest spot on the tray. Put the clean and dry pan setup back on the motor and fill. Let sit over night and check the oil level on stick. This should be the correct level. Mark and you are done. Sorry for long story, FE forum also has info on this. If you are running a large system of more than 6 quarts, runing dry on turns shouldn't be an issue, less than I would overfill the motor 1 quart. I have been doing this on all my motors for the last 40+ years. I don't worry about a small oil leaks. I don't like them but at $20,000.00+ to build these motors, let them sweat.
Good luck with repair. Rick L.