Scott's Miura on California Coast Highway 1, between Carmel and Big Sur. August, 2010.

Precision machining the custom MiurEssence oil pump housing.

Machining the custom MiurEssence dual filter housing.

Machining the custom MiurEssence pan casting in its fixture.

Machined pan casting with parts, prior to final assembly.

Removing the cylinder liners from the block.

Measuring the relationship between the block's crankshaft centerline, the locating points for the oil pump housing and the camshaft drive sprocket gears. This was done back in 2007 when I was designing my first prototype oil pump housing.

Bare Miura block.

In order to position the block accurately for decking the head gasket surface, a fixture was built to hold and align the block along the crankshaft bore centerline.

The head surface of the block had been deformed by the head stud tension, requiring a "skim" machining of the surface to true it up. Aligning the block on the milling machine took hours; since the specification for the cylinder height above the aluminum deck is .0035 to .004", the alignment of the block had to be "perfect" for this operation, and also for the follow-up machining of the tops of the cyliner liners after they were re-installed.

Custom head studs designed by Bob Wallace screw into the meaty portion of the block around the bottom of the cylinder liners, requiring drilling and tapping.

Comparison of the original studs that screw into the top of the deck, and the new studs that screw into the lower portion of the block. My fairly early (#182) Miura cam equipped with 10mm studs; later Miuras were equipped with 11mm studs. The new custom studs are 11mm above the deck (into the heads) and 14mm into the base block. The new studs cannot be used in the front and rearmost locations (8 total) due to the block design (see undercut below front studs); however, these 8 locations are better reinforced and don't require the new studs. I did have to replace these 8 studs with the later, 11mm standard version studs. Notice that the machining for the custom studs cuts into the water jacket, so the studs are equipped with o-rings to seal the coolant from the deck surface.

New head stud screwed in. Notice how the block material for the front stud extends down the bottom of the water jacket opening, providing better support than all of the interior stud bosses.

Cylinder liners were vacuum sealed and put into the freezer to shrink them prior to installation back into the block.

Two old electric ovens were salvaged and pieced together around the Miura block on the engine stand. The block was heated for several hours up to 280 degrees F, to expand it prior to inserting the cylinder liners.

Cold cylinder liners slide into the hot block quite easily, as long as they are aligned properly. After pushing the liners into the block, a special tool was used to ensure that the cylinders were firmly planted against the shoulder in the block. If a cylinder liner is not fully seated at this point, it will move after the engine is completed, and the head gasket will lose its seal. After this operation is complete, the tops of the cylinder liners were decked to obtain the .0035 to .004" height above the aluminum deck. Again, precise alignment on the milling machine was required.

Head plates were fabricated, and I took my block to Eddie Conrad, in Houston, to perform a final hone and straighten out the bell shaped cylinders that the previous shop had produced. Luckily, the cylinder to piston clearance had been too tight from the previous shop, allowing a little less than .002" to work with. The finished cylinders had a nice 400 grit cross hatch pattern.

The block is ready for assembly.

I had to have my crankshaft done twice. The first time it came back to me bent .0025" (TIR) and with chrome plated journals that had cracks in the journal fillets. I did a lot of checking and ended up sending it to David Eden at Marine Crankshaft Inc in Irvine, California. Marine Crankshaft did a great job. They removed all the chrome plating, built up the journals with steel, finish machined, balanced, heat treated, ion-nitrided and micro-polished it. All dimensions were well within the specifications I provided. The only issue I had was that I specified a slightly larger fillet on the journals than the factory specified, and they were big enough to interfere with the end play of the crank (see below).

Lathe fixture to hold the main inserts and chamfer them to clear the crankshaft journal radii.

Aftermarket pistons with non-factory dome and coating on the skirts.

I always wanted a set of Carrillo rods, and when I was informed of the price to rework my original rods with improved studs and nuts, I decided to spend a little more for the Carrillo rods. This was back in 2000, and the price of Carrillo rods has about doubled since then, I understand. These rods are so beautiful, it is a shame that they are hidden inside the engine.

During trial fit, I discovered that the valve spring retainers hit the tops of the valve guide seals. I had previously measured, and there should have been clearance. Investigation revealed that the valve guide seals were not seating all the way because they tapered inward near the top, and would not clear the rounded shoulder on the top of the guides. Chamfering the tops of the guides fixed this problem without shortening or sinking the valve guides.

The first machine shop gave me new valve guides that were loose at the top and bottom but tight in the middle ("pinched"), steel valve seats that were not completely seated into the aluminum combustion chamber material, and inconsistent valve to seat patterns. The camshaft bearing surfaces were also ruined, with one journal having .022" clearance. Needless to say, the heads were unusable. The cost from the first shop was high, but it cost me twice that amount to fix all of the damage. Notice the excellent finish on the new cam journal surfaces ... they were bored oversize to clean up the mess created at the first shop, and then the camshafts journals were hard chrome plated oversize to obtain .002" clearance. I also got tungsten carbide valve seats that were cut with a computer controlled machine that provided identical valve to seat patterns.

One thing I greatly dislike is an engine that smokes at any time. Many Lamborghini vintage V12's smoke at start up, usually caused by oil down the valve guides. These valve guide seals, along with new valves, valve guides and valve seats, have resulted in a clean starting and running engine.

CCing the combustion chambers. The piston dome volume was also determined by this method, to determine the factory and new compression ratios.

The change from 10mm to 11mm diameter studs required opening up the stud holes in the heads.

The exhaust valve to piston clearance is very close in my engine, requiring close attention to camshaft timing. I wanted to make sure that I did not have any valve float, and the springs I had procured back in 2000 were quite weak (80 lbs on the seat). After a long search for springs with the specifications I wanted, I ended up ordering a special run of springs. Hence, the springs available from this web site.

The top deck of the pistons, in the area over the rings, extended above the cylinders, with less than adequate clearance after the thickness of the head gaskets was considered. Therefore, I machined down the tops of the pistons for clearance. The weights of the pistons stayed equal after this machining operation.

After machining the tops of the pistons, I used clay and solder to measure/verify the clearance.

The engine is coming together.

View of the block-off plates required to keep the oil in the separated transmission case from running into the transfer case area.

The transfer case cover must be modified to clear the shift rod opening sealing cover.

Using a high quality camshaft assembly paste is extremely important for the initial run-in of new camshafts and/or followers. Most of the new oils in the US have lowered levels of zinc phosphate (ZDDP) to lengthen the life of catalytic converters, so either specialty oils with adequate percentages of ZDDP, or a ZDDP additive is necessary in older, flat tappet engines. I have been very satisfied with the ZDDPlus oil additive and their camshaft break-in paste, seen in this photo. It is also important to run the engine at 1500 RPM or more for the first 15 to 20 minutes immediately after initial fire-up to get the cam lobes seated to the followers without damage.

Basic engine sitting in chassis.

Getting close to initial fire up.

Video which shows how oil drains back to the scavenge pumps at different phases of operation and engine temperatures.