Great pics!! Now give us the specs on the race car. And the street car too.
The street Z is all stock, an original, one owner car. They came with a 150hp inline overhead cam 6 with dual SU carburetors. This one has the automatic (ugh!) which is essentially a carbon copy of the Ford (C6?) automatic that came in small Ford sedans like the Fairlane and Maverick.
I still have it, but it is due for a major renovation, paint, engine, suspension (upgrades) and swap the auto out for a 4 or 5 speed manual gearbox. Plus I have a set of 15x7 Panasport wheels for it. The car will look very nice when the rebuild is done (if I can ever get the time!).
The race car is (at the time the picture was taken) set up to run in a production based class, an ICSCC (International Conference of Sports Car Clubs) class rule. On "street" tires it ran in E Production, on slicks it ran in D Production. ICSCC is a regional road racing club that has racing meets similar to the SCCA, you can read more about the club here:
International Conference of Sports Car Clubs
The class allows for balancing and blueprinting of the engine, port matching and cylinder head "cleanup" but no alterations to the stock configuration. Although the camshaft is a stock grind, there are "tricks" that can be done to gain a little extra lift and duration, which of course I have done. There is also an ACCEL high output coil and a Pertronix hall effect trigger that replaces the points. I added an Oberg plate type remote oil filter and a large oil cooler (without it the oil would get so hot the engine would lose lubrication in about 10 minutes of hard running on track).
The class requires the stock intake system be used. These cars came with dual SU carburetors, which are very tunable. Additionally, when I had the head built the guy also worked over the carbs, intake and exhaust manifolds.
Any exhaust system is allowed provided the stock manifold is used, and I was burning my right foot during a race (the exhaust runs alongside the transmission in the tunnel) so I had a shop bend up some tubing and built the sidepipe you see in the pictures. The muffler is called a "Lowback". Although it looks like a glasspack it is not. There is a small tube running through the center (1/2" diameter) and a piece of flat material twisted into a spiral around it that just fits inside the outer part, is s;id in and welded in place. It makes for a great muffler that gets the sound levels at or below what the rules require (I think it is 105 decibels measured at 50 feet from the track), never really wears out (I had the whole setup aluminum coated in and out) and I don't burn my foot anymore.
The engine at this stage of development makes about 250 horsepower.
Stock transmission with a heavy duty clutch. In the 20 years I ran this car I only had clutch troubles one time. One of the bi-metal pieces that hold the pressure plate in the cover broke, and the pressure plate got off center. It really made the car shake. I was a couple laps from the end of a race and running up front, so I kept on going. It made it to the checkered flag, and when I got home I pulled the tranny and replaced the clutch. It still has that clutch in it today.
The suspension is still stock configuration with larger anti-roll bars, aftermarket strut cartridges (adjustable dampening) and springs, adjustable inner pivot points on the lower control arms. The class allows slicks (D) or street tires (E). The slicks are long ago out of production, and the various tire manufacturers offer great DOT approved tires that work every bit as well as a slick tire, they just have the required DOT approval and one or two grooves with 3/32 (I think) tread molded new. The compound is very sticky. And for rain you can use the autocross tread compound which has even better grip, but don't run them on a dry track, or even a wet track after the rain stops.
Since the class required using the stock brake setup but the linings are free, I was having a local shop make up shoes for the back and pads for the front using the same material that is used on commercial jet airliners. It worked great, didn't require bedding in, and the material gave consistent and reliable braking cold or hot, and believe me, the brakes get hot. I also added 2 cooling ducts to each front brake and one to each rear.
As required by the safety rules the car has a full roll cage, 5 point harness, window net and a Halon fire suppression system. I also mounted a 15 gallon fuel cell with dual pickups and 2 fuel pumps.
I am now changing the car to a GT class spec. Semi-tube frame, fiberglass hood, fenders, doors and hatch, wider wheels and tires (slicks are available for the size I will be using), and bigger brakes (including disc on the rear to replace the stock drums). I will be ditching the SU carbs for fuel injection, a throttle body and injector for each cylinder. The distributor will go away in favor of crank triggered direct ignition. I'll use an L28 cylinder block, over-bored and a diesel crank which should get the displacement just over 3 liters. Forged pistons with the bump to get the compression ration up and valve reliefs to clear the valves. I've already put larger valves in the head, shaved it and opened the ports up as big as they can go. And of course a more radical cam grind.
The flywheel and clutch will change too, there is a competition flywheel available that uses a small diameter multi-disc clutch. Also a custom made vibration dampener, and a dry sum oiling set -up.
It has been a few years since I ran the car. The last time I ran it was at Thunderhill in Willows, California, where the two pictures of me on track here were taken. One of the fuel pumps quit, and the engine ran lean, and then scuffed the pistons. At the time I didn't have the money to build another engine, so I rented a seat in a few different cars from fellow club members. A Mazda Miata (lots of fun, kind of like a go-kart, only bigger), several first gen Mazda RX-7's (also fun and fast but too small for me) and the last car I rented was a second gen Mazda RX-7, by far the most fun of all the cars I have rented and very fast. It was even able to run in the same class I had been running in my Z, and I won the race I had entered with it.
I'll have to dig around and find the pictures of the other cars I have ran in. They're around here somewhere.