Some ideas...

[Squeeks]

Hello!

I just got back to Germany from Denver and totally enjoyed driving the '73 240Z that my wife bought me for my birthday. After having driven it for a week I am confident that I am aware of most major problems the car is suffering from.

Aside from the exterior and interior cosmetic stuff the most important things would be engine, transmission and coolant leak.

The engine burns ALOT of gas...I mean like half a tank in 100 miles. That seems excessive to me.

It blows smoke out the tailpipe when cold and really reeks of gas at times when driving around town. Might just need a tune-up but if that fuel economy is normal then I better find some oil reserves in my back yard.

The tranny seems to be alright...for the most part. I did notice on a few occasions that when the car was warmed up and I was just cruising down the road it seemed to "push and pull", that is, it wasn't a steady drive but hesitant, almost like you would expect when the car runs out of gas.

The RPMs were steady and the engine was smooth.

Also, the interior floor boards were sprayed in coolant one morning after I tried to get some heat on the night before, is it correct to assume that there is a heat exchange coil under the dash board?

So, to the ideas...I am curious if it is possible to replace the existing engine and transmission with any engine and transmission of my choosing...I can't see why it wouldn't be possible and what engine/transmission combos you guys and girls out there have installed with great success.

I am looking for great performance with "enhancements possible" and good fuel economy. I know it is possible as the Mitsubishi Lancer Evo has some nice performance and respectable MPGs.

Thnx!! --- Squeeks

[Bruce Palmer]

I'll speak to the carbs. Your pushing and pulling sounds like surging which is an indication the carbs are less than sport on. Are your carbs round tops or flat on top like a tuna can?

If flat tops, they were questionable when new to the extent NISSAN replaced a lot of them with the round tops when those cars were new because of custome complaints. Some on here state they have had gook luck with the flat top carbs and I have to guess that even the worst diseign has to be right in some cases but at 36 years old maybe it's time. We still supply the early carbs to this day for those who have grown tired of fighting the flat tops after 30 something years. Our price list shows 2 iterations of early carb changeovers. If that is of interest, take a look at the price list.

Cheers

[=Enigma=]

Congrats on making it home and for finally getting to drive your new (to you) car. Bruce already covered the surging, which is likely due to the carbs being out of tune among other things. These can be partially rebuilt and Bruce has a kit available with the special pliable hose you'll need for the fuel nozzle, but if the butterfly valve shaft bushings are worn excessivley it will be very difficult to sync the carbs properly, and getting the right air/fuel mix will be impossible. Ztherapy has rebuilt carbs available if needed. The excessive fuel usage may be stuck nozzles, floats, an improper tune, worn, cracked or leaking parts, and can definitely be corrected. A properly running L24 should get around 18-22 mpg depending on condition, mods and driving style.

The coolant leak on your floor is from the heater core, one of the hoses, or the heater control valve itself. All are still available from various sources.

On the tranny the push/pull you felt is likely related to the surging carbs, or worn, cracked or shot engine, tranny, or differential mounting isolators. Again, all are available in stock or poly from various sources.

There are lots of engines that can be swapped into the Z due to the large amount of space up front, however most of us on this site have chosen to stick with the original L6 block in stock or modified versions. Anything else is typically considered a hybrid and there is a seperate site devoted mainly to that among other things. Obviously the choice is yours, but I encourage you to get your existing motor running correctly and enjoy the car for a while until you decide what to do.

Check the following part sources:

www.courtesyparts.com

www.ztherapy.com

www.zcarparts.com

www.blackdragonauto.com

Edited June 17, 2009 by =Enigma=

[Travel'n Man]

The engine burns ALOT of gas...I mean like half a tank in 100 miles. That seems excessive to me.

It blows smoke out the tailpipe when cold and really reeks of gas at times when driving around town. Might just need a tune-up but if that fuel economy is normal then I better find some oil reserves in my back yard.

I would look under your car and around the gas tank area and see if you have any fuel line leaks. Also, remove the right side interior rear hatch panel and the tail light panel (from inside the car) and inspect all fuel lines in there. It sounds like you have a fuel leak. I think that would be the first thing I would look at and get corrected. Most any auto store will have replacement fuel line.

[Carl Beck]

Hello!

The engine burns ALOT of gas...I mean like half a tank in 100 miles. That seems excessive to me.

Fuel Leaks:

The fuel use you describe is usually from leaking gas somewhere.

There is a long plastic filler neck, that runs from the exterior of the body to the fuel tank. It is common for them to be cracked and leak fuel when the tank is more than half full. Second most common is the rubber fuel supply and return lines. They run from/to the hard lines under the car from/to the fuel tank.

If you are sure you have no leaks - then get your carb's sorted out - and be sure to change the oil in the engine. That rich a fuel mixture will wash oil off the cylinder walls and dilute the oil with gasoline. NOT GOOD!!. Check your engine oil level, and see if it is increasing as you drive the car.

FWIW,

Carl B.

[Carl Beck]

If flat tops, they were questionable when new to the extent NISSAN replaced a lot of them with the round tops when those cars were new because of custome complaints.

Hi Bruce:

Don't know where you got that idea - but Nissan Never Replaced the Emissions Certified "Flat Tops" with the older "Round Tops". Rather Nissan worked for months to identify and correct the problems they had with the "Flat Tops". Due to Federal Laws, any Dealer that disabled or removed any emissions control devices - would have been subject to very heavy fines, and could have lost their Dealer Licenses.

I do know that several Service Managers - made personal recommendations to customers, that "the customers" swap out the Flat Tops for the Round Tops as the Federal Laws at the time did not apply to privately owned vehicles.

FWIW,

Carl B.

[Arne]

Hi Bruce:

Don't know where you got that idea - but Nissan Never Replaced the Emissions Certified "Flat Tops" with the older "Round Tops". Rather Nissan worked for months to identify and correct the problems they had with the "Flat Tops". Due to Federal Laws, any Dealer that disabled or removed any emissions control devices - would have been subject to very heavy fines, and could have lost their Dealer Licenses.

I do know that several Service Managers - made personal recommendations to customers, that "the customers" swap out the Flat Tops for the Round Tops as the Federal Laws at the time did not apply to privately owned vehicles.

FWIW,

Carl B.

All true, Carl, any dealer who retro-fitted round-tops on a customer's car would be subject to fines, if caught. But I too have talked to a couple of original owners of '73s here in Oregon who swear that their dealer made the switch for them. In both cases the owners had to buy the carbs (no "warranty" or similar), but the carbs were installed in the dealers' service departments. Since Oregon back then had no emissions testing, I suppose the dealers figured the chances of getting caught were almost nil.

[Bruce Palmer]

Carl,

That may have been the way things were cast in stone for the regulators to view, but I know owners of those "new" cars that had the swap done by dealers..... There have also been several customers over the last 8 years tell me they'd also had it done because they could never get them to run.

Here's an interesting read on Laws and regulations - In south Louisiana the Cajuns say the only reason there are laws in the state are to keep the Baptists in the northern half of the state in line. None apply south of Alexandria....

Cheers

[sblake01]

I also know stories similar to Arne's here in California.

[Squeeks]

Thanks!

Very sound advice.

The carbs are aftermarket Webers. I would sure like fuel injection, carbs have always seemed to be a weak link in every car I ever owned that had them.

Can't wait to get back to the States to get started on the car.