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'74 260z F54 Upgrade - 2 Engines to build!


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Im Andy - ex Engineer from the mining and energy industries with a passion for cars. Just started on my retirement project which is to rebuild a 1974 260z 2+2 to original body characteristics but with upgraded engine and running gear. I will also be building a second engine for fitting into the car at a later date to race in track days and enter hill climbs in Australia. The car's present condition is quite good as the body has no rust that I can see (although all will be revealed when it gets blasted to get rid of the FORD!! Mica Blue respray that was done about 5 years ago. The original colour is Silver but I am not sure if it is 901 or 306 metallic (anyone have the years that these two colours were used??). I want to return it to its original colour. The interior is stripped apart from the dashboard which will come out soon as I want the shell absolutely clean to blast it. I have most of the interior components but will need to re-upholster the roof lining and carpeting completely. Seats are in reasonable condition as is the dash and door panels. The only bodywork I will fit to enhance the car will be a front air dam. With the car purchase of AU$5,000 and parts / tools I have already coughed up AU$17,000 and expect to spend another AU$20-25k by the time the car is in tip top condition. I intend to show it as a Sydney Z Club Member in future meets! This restoring game aint cheap! Having a road AND a race setup might be a bit extravagant but its my big hobby so I am in no rush but want to make a real good job of it.

 

The outline of the project is as follows:

  1. Strip & rebuild L26 engine - A. repair and rework head. It is an E30 off a Skyline (I think) and was not in the best condition. I know this head hasnt got a good reputation for Zs but I think it's worth having a go with to maximise the high CR in a NA setup. So I have installed N42 valves, new seats and new valve guides. I will port and polish  the head and fit 9000 RPM springs, lightened and balanced rockers, a Camtech 702 camshaft (high lift and long duration but still with some low end grunt) and then work on the chamber. It's a 37cc high quench head so with the larger valves installed will require some un-shrouding around the exhaust valve especially but also a little around the intake. No skimming (apart from a very minor cleaning skim) will be required. The porting will be done to try to keep reasonable flow velocities to assist with torque. B. Rebore the block - (Measuring the cylinder bores showed both taper and out-of-round was greater than tolerance limits so the block will be oversize bored to the max I can get). Having it sonic tested to see if the walls will take a 3mm oversize to 86mm pistons but my guess is that I will have to settle for less. Assuming a 1mm oversize pistons (flat top) and a 1mm metal gasket the CR will be about 11.23:1 using standard stroke conrods. This is high but we can get 98 Octane fuel here at the gas station and so shouldn't be a problem with good timing setup. All conrods will be worked on and balanced as a set. Pistons will be cast. © I will be fitting a modified timing gear kit by Kameari to replace the standard setup which should assist the accuracy of the timing along with the uprated springs and lightened rockers. (D) there will be other small mods such as upgrading the oil supply with a high rate pump and fitting a new dizzy, leads and coil setup etc...
  2. Install triple 40DCOE Webers onto a Canon manifold fed by a Holley 90GPH fuel pump regulated to 4psi. Not decided yet on the intake filtering but I might go for modifying the standard intake box repositioned with a RAM AIr attachment (which I will have to custom make).
  3. Fit a custom exhaust header and 6-2-1 piping. This lot came with the car and is 11/2" headers going into 2 x 13/4 " collectors into a single 2 3/4" exhaust. It's in good nick and the rear box looks fine.
  4. Fit uprated discs at the front and a rear disc conversion kit. Not sure if I really need ventilated rotors at this stage but will have a race set to fit to the hill climb setup in future.
  5. Suspension. I have not decided yet on what to do for the suspension. Ideally I would like to get hold of a modern system that can be controlled by the ECU for various conditions and then custom fit to the Z's chassis. Possibly a bit of a pipe dream! Otherwise I will get the best I can for the car from what's available at a reasonable cost (probable need 2 setups for road and race).
  6. Strip and rebuild L28(F54). I have purchased an L28 engine with an F54 Block and N42 head. The engine has a hot cam fitted already to the reworked (flowed) N42 head so I might keep this however, this engine will become a turbocharged unit. I am in the midst of reading Corky Bell's book Maximum Boost and learning all I can about turbos and how to get the best out of one. Also reading as much as I can in these forums (thanks!). I want to stroke the engine so will be after a LD28 crank and all of the kit to go with that if anyone has one for sale?? This will be a long term project but hopefully result in a beaut of an engine kicking out 400HP plus. I know it will be a lot of work and expense but will be worth it in the end and very rewarding to work on.

That's about it for now. Will keep it updated. 

Edited by andypurce
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  • 3 weeks later...

Update on the L26 re-bore. The sonic test showed more than enough wall thickness for a 3mm oversize so the 86mm bore is done, cylinders honed and new flat top pistons fitted. Interesting note: One of the brand new set of ITM pistons was 1/1000 undersized to the other 5!! So this cylinder is bored out 1/1000 less than the others. Getting it back tomorrow and looking forward to fitting new main journals and re-installing the crank. The L28 crank I have is a beaut. On the dial gauge all of the crank pins and main journals were within tolerance as was the centre bending offset. Fantastic for a 30+ year old crankshaft!

Just porting the head intake and exhaust runners at the moment and grinding / balancing the conrods to within 1-2g of each other for a lovely smooth bottom end. 

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  • 2 weeks later...

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