Gordon Dobie

Check the piston travel by lifting them with your finger or a screwdriver placed under the piston. It is quite common to find the pistons have been placed on the wrong carb's, this can result in the needles binding in the jet. If they don't return to the fully closed position try fitting the front piston ass'y in the rear carb' and visa versa. Also check the fitting of the needle in the piston. The flat underside of the needle boss should be flush with the bottom face of the piston. Cheers Gordon Dobie

40mm Dellortos are most commonly ex Alfa Romeo. These carbies work fine on L series engines but require a modification to the idle circuit. Without this mod' the engine will 'hunt' under light load and at cruise. I some regards these carbies are better than Webers in fact my race car Built in 1973 used 3 x 50mm Dellortos producing 295 BHP and 244 Ft Lbs torque from 2700cc's. Cheers Gordon Dobie

You say your car is running fine. That makes you a lot better off than some vizcar members. Life's to short to look for problems. Remember the old maxim " If it ain't broke don't fix it" Cheers Gordon Dobie

The clearance between the piston and carbie body is critical to performance and under no circumstance should any abrasive be used which would affect this clearance. Oil should not be applied to the piston bore. Auto transmition fluid is the correct viscosity for the piston damper. Cheers Gordon Dobie

A cause of fouled plugs can be fouled injectors. Over time a wax resdue can build up in the injectors causing a poor spray pattern. The injectors should emit a fine mist in an umbrella Patten which will vaporise almost instantly but when the injectors are clogged with wax they deliver a jet of wet fuel which does not vaporise properly. Wet fuel won't burn fully resulting in excess carbon deposits on the plugs and as carbon is an exceltent electrical conductor the electric current tracks through the carbon instead of jumping the plug gap. The unburnt fuel eventually vaporises and burns then exits the exhaust in a black cloud. The solution is have the injectors cleaned and use injector cleaner in your fuel tank every couple of months. Gordon Dobie Datsun Racing Team Chief Engineer (retired)

Removal of the cam towers will not cause a problem. A common cause of the camshaft binding in the cam towers is a warped head due to a blown head gasket. If the head is surface ground on the gasket surface it is essential that the top surface is also machined or the cam towers will be out of alignment. Alliteratively appropriate thickness shims can be placed under the towers to bring them back into alignment. If the head is bent more than .005" it should be straightened to within .005" prior to machining. Gordon Dobie Datun Racing Team Chief Engineer (Retired)

The 260Z SUs have had a lot of "bad press" mainly due to the fact that most mechanics don't understant the basic design pricipals or how to go about tuning them. The first thing to check is the float level. A small window is provided in the front of each carbie for this purpose. The fuel should be level with the small dot in the centre of the window. If this is correct and assuming some "bush mechanic" has not been fiddling with the factory settings the carbs will do the job they where designed for. The fuel level is usualy too high due to worn neeldles and seats. Replacement of the needles and seats should bring the float level back to the original settings. Another possible cause of a high float level can be a sunken float. Solution, replace the float. Gordon Dobie

If your car is primarily a road car the carbs are too big. The air flow through 45mm carbs when fitted to an engine with cylinders of less than 530cc's is too slow the result of which is poor atomisation of the fuel. Wet fuel won't burn (only the vapour burns) resulting in a rich mixture, poor throttle response and lack of power. The correct size for a L240/60/80 engine is 40mm with 32mm chokes. Fuel injection systems can tolerate much larger throttle sizes due to the fact that the fuel is delivered via the injectors as fine mist which vaporizes almost instantly. This also explains the reason for improved fuel economy when compared with carburetors. Cheers Gordon Dobie

Hi Gavin I don't know if this qualifies as a "feature car" but I thought you may find these photo's interesting. The first shows No 54 in GT guise in the Australian GT Championship series. The car following is a works Porche Turbo driven by Colin Bond. The race was won by Alan Jones in an 800 horse power Porche 956 twin turbo. The second is a shot of the same car running under Improved production Sports Car rules ( no splitter or rear wing). This car held a number of class records. The black and white shot shows me about to lap Ferdi's similar car fitted with G nose in the Australian Sports Car Championship round At Winton some time in the 80s. Best wishes Gordon Dobie

Hello Kent If your box is a very early one the gear stick goes through two tapered rubber bushes and is held in place by a nut on the bottom of the stick. Various parts of the mechanism are exposed to oil and road grime which forms a sort of grinding past on the moving parts. This is a major cause of excess play in the gear shift. There is a simple fix for this problem. Give me a ring on 0409 02 8181 and I will explain how it can be done. Cheers Gordon Dobie

]The Nissan R380s pictured competed in the Surfers 12 hour fitted with Prince Skyline engines with twincam fuel injected heads. I remember being surprised to find that they arrived from Japan with only one spare wheel each and no other spare parts. The driver of the winning car over revved the engine in practice resulting in a bent exhaust valve. When I spoke to the Japanese team chief about this he said "not to worry, when valves get hot in race they will straighten" This proved to be the case as the car had a trouble free run to win the race against the fastest sports cars in the country including a 250LM Ferrari, 5 litre V8 Lola, Matich V8 etc. Gordon Dobie[/b]

Having retired five years ago I am in the process of winding up my business and will be selling off all of my stock and equipment. I have a number of low mileage Z engines and gearboxes diffs etc. Some of these have done as little as 20,000 miles. I also have a small number of body panels. Any auszcar members are welcome to these parts at about half of their real value. Gordon Dobie datcar54@hotmail.com

Having recently discovered the VICZCAR site. I am surprised and pleased at the interest shown in the early days of the Datsun Racing Team. The secret of the success of the Datsuns of that period was their incredible reliability enabling huge increases in power and RPM. This is evident by the fact that today more than 40 years later these cars are still competitive. The basic design of the 1600 sedan and the 240/260Z was one of the best handling packages available at any price and yet the cars were incredably inexpensive. A 1600 sedan cost slightly less than $2000 and the cost of a 1000 sedan was around $1000 making them very competitive in events such as Bathurst where the classes were based on price and no modifications were permited. Unfortunately in 1970 CAMS in responce to a lobby from the V8 manufacturers (The big V8s were notoriously unreliable at racing speeds) decided to allow modifications. The result of this was that the cars ceased to be representative of the cars sold to the public. This for me and many other enthusiasts removed a lot of the interest from this form of racing, but it was great while it lasted as it truly demonstrated to the public the strengths and weaknesses of the various makes. Gordon Dobie

Hi The Datsun 240/260 Z range of cars do not comply with CAMS Touring car reg's and are therefore ineligible to run int the Bathurst race. The Z shown in the photo's was built in 1973 by Auto Developments / Datsun Performance Centre, then located at 54 Beach Road Hampton, for Peter Tobin. The car was a 240Z updated to 260 specs to comply with improved production sports car rules producing 295 BHP and 244 Ft/Lbs of torque. Peter raced the car at local Victorian circuits for a couple of years. I purchased the car and rebuilt it in the late 70's and raced it with considerable success in the Victorian rounds of the Australian Sports Car Championships and the Victorian and Australian Hill Climb Champ's in the 70's and 80's. This car was by far the fastest Z raced in Australia proving it's superiority over the Porches etc on a number of occasions . At the time I was also campaigning the Ex works Datsun 2000 featured on my website at www.datperform.com. Gordon Dobie