Datsun Roadster Forum-311s.org

Greetings All. First off, thanks for the site, and the Forum is a great source of info and has motivated me to get my Beast fininshed, well at least back on the road.

I recently put in a rebuilt U-20 motor that has the solex/mikuni's. Does anyone know what size cap / thread the return fitting on a 1968 fuel tank is? I have already removed the return fuel lines. The PO just put a plastic cap on it with a ring clamp, which worked fine since the car was only used for AutoX, but now it's in a (hopefully) daily/weekend driver.

Also, I got a complete Nissan Oil cooler in a box of spare parts with the car. It even still has the black plastic cover that says DATSUN FAIRLADY to put over the fins in cold weather. Can I hook it up for a daily driver to put more oil capacity in the system since I still have the stock oil pan? The PO said it never ran hot, and it was not hooked up on the engine when I bought it. Thanks.

Happy Wrenching
Mark

Mark,
I'd kill for that oil cooler, its the last bit of "insurance" I want for my enigne. As for the fuel return line, I took the fitting I had down to the hardware store and found a cap that fits. I think it was $3.

good luck,
Will

Mark,

Do you have a picture of the oil cooler you can share. I have the adapter and oil cooler lines for a U20, but no cooler. I was wondering what it looked like and where exactly it mounted.

JC

You can use the return line with the solex carbs! I have seen it done on a right hand drive car - either Aussie or JDM. They had a valve just like the SU carbs, just in a different shape. The one that Rallye sells as an option would be ideal.

Just a thought.

Oh, the oil cooler mounts to the front crossmember with the 4 phillips head screws that are there. I have not measured it, but an MGB unit looks awfully close...

I tried the return line and just found that once the care was warm, the gas juste evaporated and pressurised the tank. I didn't have any returning to the tank. I checked to see if it was working by starting the car cold, and had gas flowing out, once the car got hot, it just had vapor coming out. I capped it, and just ran the fuel lines into the float bowls with no return.

Will

Will,

Your tank should not be pressurizing since it has a breather tube. By pressurizing it would force the fuel in the line to go back to the carbs.

Alexi

It was causing it to do something, if I opened the cap after a long drive, it held lots of pressure. It was causing other wierd problems as well. After I undid the setup, the tank had far less pressure (think opening a hot radiator to opening a standard gascap.) The wierd problems went away as well. I failed to mention I was splitting a line off the main fuel line to run the float bowl coolers in the carbs. They didn't make a difference, and the pressureized tank just wasn't cool (no pun intended).

Will

If you just had a T fitting, that is not the best way to go. The valve on the back carb only lets fuel return to the tank to prevent vapor lock. It is not vital, but it can help folks in a hot climate.

Thanks to everyone for all the input. Sid, I 'll shoot Dann an e-mail on Thursday or Friday. Looking at his website it should be a relatively easy install. I tried to make the SU return work but it was just plain and simple the wrong part. I would prefer to have the valve just as a precautionary item, but then again the Solex 67.5's and earlier cars w/ the SU's never had a fuel return, and most Solex roadsters appear not to have one.
JC, I'll take some pics this weekend as well as get some approximate dimensions. Right now it is in a box of parts out in the shed. Sid is right, it mounts in front of the radiator where the 4 philips head screws are (should be - mine were missing but were there on the parts car) on the cross member.
I thought I read somewhere once many moons ago, before I had the oil cooler, that you had to increase the oil pump output somehow? Bob Sharp manual maybe??

Happy Wrenching

Mark

Just cap the return line and run the fuel line straight into the carbs, running a T intersection, the bottom going to the front carb, the other one going to the rear carb. Thats what I did, it has never vapor locked on me, doesn't leak, looks clean as well.

Will

JC - the dimensions of the Oil Cooler are +/- 1.5" deep x 4" tall x 12 3/8" wide. The fittings on top of the cooler stick up another 1" in height and the lower flange that attaches the cooler to the cross member adds 1" to each side of the cooler. Just in case anyone is curious the part # stamped in the oil filter mount is 15238 25570 . I don't see any part #'s on the hoses, cooler itself, or the cover. I put a pick in the public album: http://www.311s.org/phpBB2/album_pic.php?pic_id=67
If you want any additional pics let me know and I'll e-mail you some

Happy Wrenching
Mark

I was under the impression that the line was not for fuel at all. The valve between the carb and return line allows vapor to pass to prevent vapor lock. It does not return fuel to the tank like modern fuel injected motors.

Andy

Mark,

Thanks for the pic and info. It looks much like a Jag, MG, Truimph cooler. I will look into the adaption of another make, but the cover is cool !!!!!!!!
Know anyone who could make a cover like that?

JC

Sid

I just got the "alternative" fuel return valve from Rallye today. Looks like it should work with minimal effort. From what it looks like taking a quick peek this evening I'll have to straighten out fuel in tube and maybe use an extra washer on the bango bolt since it looks thinner than the fuel bango originally on the carbs. (I'll dig around in the shed, maybe the SU bolt is shorter.) The support it came with will not work, but again should be an easy fix to rig something up. The suppourt that held the fuel bango in place that was on my Solexes will not work with the new valve. Wonder if I could just put lock-tite on the threads when I tighten it, or would the vibration of the motor loosen it up? The front carb on the SU never had a bracket (Or was mine just missing?) If I get a chance I'll put it on this weekend and post some pix. Thanks again for everyone's input.':D'

Mark

Mark,

You don't need the support bracket. That valve was originally off of some other car, but it is VERY close to the OEM unit that I saw on the RHD car. It should work OK. I doubt that you will need the double washers, but you may. I would not use lock tight - carb castings are getting tough to come by!

On the oil cooler, the location mentioned on the frame was the original location, but I forgot to mention that there was an optional assembly that moved the cooler down below the valence panel. It is a goofy looking contraption that I have only seen on JDM websites. Someone over there even reproduced it and did a nice job of it.

I kind of want an oil cooler assembly, but it is not a high priority. Just a cool "gee whiz" part for me. Kind of like my chromed factory roll bar...