I have a 78 510 l20b I have had the car for about 6 years now purchased for $100. Recently re-worked the head, suspension all around, clutch/pressure plate etc, and brakes. I am starting to have some problems though and need some direction and sugestions. The car is mostly stock other than a huge webber 2bbl. Since i first had the car i got A LOT! of black smoke at high rpms (4500ish+) other than that and some startups after sitting for a few days it is smoke free however recently i have noticed a drastic power loss and im worried it might be on its last legs, aprox. 240k mi. on the car all original other than the mentioned above work.

First question: I am concidering what to do about a motor, I want to keep the reliablility that the car has had to this point but i would also like to see a power increase (who wouldnt). Should I just rebuild my bottom end or concider a swap? I currently get aprox. 29-31 mpg city, which i really dont want to lose, with slightly less highway.

Also I have some serious concern about the smoke, people have sugested that it might be a poor tuning on the carb and since I have little experience with that then its very possible but i get such smooth drive in lower rpms with excelent mpg im not sure thats the problem.

My next concern is that this is not a very good highway car i sit at uncomfterbly high rpms at 70-75mph 4000? I dont have a tach on the car so Im having to guess from when I had a tach for a day. Is the only option to fix this new transmition/axle? I have a 5 speed and i really like my positive traction rear. I would rather not have to change any of this out since i do very little highway driving.

Basicly all around what im looking for is a way to get my worn out car back to something i can be a little less timid about taking on long trips. I have only about $1000 to spend and engine rebuild would be pushing my mechanical skills a bit but i might could pull it off. Also i would love to pickup 20ish hp+.

Hmmmm ... Theres a few mixed messages there ... they didn't make 510's in 78 ... I'm assuming you have a 200b? Also its almost impossible to get better city mileage than highway...

That aside, with 240k miles on the clock, your engine almost certainly IS on its last legs. You should be able to pick up a good L20b for $500, I would think. Probably be more expensive to rebuild yours, but at least you would know exactly what you were getting and it would be a good challenge if you like that sort of thing. If you already have a 5 speed and it revs high then you would need to get a lower ratio diff centre. I don't know about solid rear axles - which you probably have - but shouldn't be too hard or expensive to either replace the centre or the whole thing.

Pick up 20hp? Well a fresh motor should give you something. Twin carbs are probably going to blow your budget. Maybe some extractors?

No doubt you will get more (and more expert) advice but those are my initial thoughts.

Cheers, Neil.

I think that they did in the US

http://www.themotorbookstore.com/datsun-510-manual.html

!!!! Hmmmm .... ok then ...... isn't that a Stanza? If so, I didn't realise that Stanzas were called 510's as well. Live and learn!

Cheers, Neil.

Just rebuild it if you want the gas milage.
They made the STANZA or to the USA a newer 510(A10 I believe)
Trying to relive the glory days of the first 510 but it didnt really work. most have gone to the crusher as I have seen nice ones not go for much in the states. Australia is a bit different and the love there STANZAs also as almost as much as the Datsun 1600.

As most Datsuns in the STATES cheap people bought cheap cars and put the same amount of time and money into them(meaning nothing!!) and let them break down and rot away.

L20b is a great motor but very exp$$$ to get alot of HP out of.
Cams, Carbs, head porting ect needs to be done and that another 1500$ to get all that stuff together and put it together your self. Machine work vost the most.

Yes it is US sorry i should have put that in my profile. Looks like this less the race stuff. My only guess is that the reason my highway mileage is so bad is the high rpms i have to run to stay at highway speeds

Guess ill try and pickup a rebuild kit and give it a patch work re-ring/bearings and gasgets to get me by till i can get some cash to do something better. Still not sure whats up with the smoke, black smoke is not oil?

Black smoke would generally be fuel, do you have soot all over the rear of your car near the exhaust? I would be thinking about getting the webber rejetted, it could be running way too rich. That alone may help push your economy up and help your power as well.