Carb Cleaning

[HuD 91gt]

Hey guys,

My 1971 Datsun 240z project has been sidelined right off the bat. Long story short, i'm not allowed to work on the vehicle in my underground anymore.

The issue, the car was sitting 6 years. Idles like… like… a poor running Datsun. With the choke out, it runs…. Well it runs. Extremely rich. With the choke in, I swear it runs on a single cylinder.

Anyhow, my simple question is. Is there anyhow I can take this carb out(Or by leaving it in), and clean it without disassembly? What I need to do, is just get the vehicle running enough so I can drive it onto a ferry and into a family members garage to get some actual maintenance and a real rebuild. The issue I see with disassembly, is the vehicle is going to be needing some adjustments, which I really can't do in my current location.

A trailer/truck/ferry ride is going to cost me a fortune, so if I can get this thing drivable in the meantime, i'd be way ahead. Any advice would be greatly appreciated. In the mean time, i'm going to drain the tank, and try cleaning on the lines, like a burglar in the night.

[tlorber]

In your description, you say "this carb". Does that mean that the SU's are no longer there?

If you are running SU's you can open remove the dashpots and piston to clean them, and you can clean most of the throttle bodies while they are in place.

Then you can remove the float bowls to clean them, the needle valves and the banjo screens. You will need new float bowl gaskets before you begin, since you will probably destroy the old ones during removal.

You should try to get hold of, or watch Z Therapy's method for setting float height. They use a spacer (appx 1/2" tall but you need exact height) to set float height correctly. I used their method but altered it slightly (I blew into a piece of fuel line that was hooked up to the fuel intake to determine exactly when the needle valve was shutting off) and set the height based upon that. My roadster has never idled better.

This all will make more sense once you watch the video, which might be on you tube somewhere.

[HuD 91gt]

Thanks for the advice. The SU's are still there. Along with my carb issues, I also have typing issues.

Can I do all of this without touching any idle screws etc, and all that will be required is setting the float height? Please ignore my "Carb" ignorance, besides some light fiddling with a motorcycle, this is my first experience with carbs. Once I get the vehicle to a proper garage, my father is a retired mechanic, and can easily help me from there.

[Bruce Palmer]

So you know the "choke on" position will make it run. What you need to do next is to reach under the carbs and make sure the nozzles are popping back up when you take the choke off. Running the car with the chokes on, or they fail to release, for awhile can crap up the plugs. Have someone pull the choke on and off while reaching underneath the carbs to make sure the nozzles are returning. If they appear sticky which is typical of varnished up gas then douche out the nozzle tube with carb cleaner to hopefully free things up. All the can be done by removing the air cleaner.

Other than that just running some fresh gas thru it after you get it running some, may help too......

No need to fart with float levels at this point. I seriously doubt anything has happened to change float levels just "sitting there".....

Let us know how you make out......

Edited April 4, 2014 by Bruce Palmer

[HuD 91gt]

^Thanks for the tip. I will try and wrangle up an extra hand and give this a shot. For now, back to the service manual and have a look for what i'm looking for.

Cheers

[Stanley]

You'll need the float bowl gaskets, a can of carb cleaner, a can of lithium spray grease (for the linkage and nozzles, after using the carb cleaner). Don't drop the pistons/needles or use muscle on anything. After cleaning per Tlorber's advice, set the mix per FSM. Make sure plugs, points, cap & rotor, dwell and timing are more or less OK before setting the mix. Especially wirebrush and gap the plugs unless they're shiny.

Figure about 5 hours if you've never done it before. Can be done anywhere, except in pouring rain. No use taking the carbs off unless you're sending them for a rebuild.

[240260280z]

I will be in Seattle in a week. Are you in Vancouver Canada?

[HuD 91gt]

Well, I went downstairs like a ninja and did a little bit of fiddling. I did as suggested and used carb cleaner on the choke/nozzle assembly. Let it dry off while I successfully managed to get to that adjuster wheel on the rear drum. Successfully got the rear drum off finally!!! I was happy to see the wheel now turned freely, as it was just the shoe rubbing up against the drum. That's a relief.

Started the car up, and it started fairly quickly. Put in the choke (Off), and it idled. I was amazed! Mind you, the original problem still exists. Barely runs, won't rev etc. I tried to rev it up a little, and once back at idle, it died. But we are definitely headed in the right direction! Next step is to get that old/new fuel (A new gallon of premium was added to the little bit of old stuff that was left) out of there, and see where we sit.

As for Blue, yup i'm in Vancouver Canada!

Edited April 4, 2014 by HuD 91gt

[HuD 91gt]

Drained the tank, put a couple gallons of fresh fuel in and it wasn't running any better. So, I was reading online about a method of revving the engine up slightly, then blocking the intake with your hand. The vacuum created could possibly dislodged some of the blockages. Not sure if this was smart or not, but the engine will not not rev up at all anymore in gear.

Either A, this created a leak somewhere between the head and the carb (I hear a hissing noise, but I'm don't recall if this was there before or not).

Or B, I clogged it up even more. The plan was to get the car out onto the street and do an oil change and do some brake work, but it now doesn't even have any power to get out of the underground garage. I can't accelerate at all when in gear. The throttle does nothing. Looks like carb disassembly may be my only option.

Also, this is for Bruce. I'm interested in purchasing the Ztherapy DVD, as I am pretty lost when staring at these things. If I do purchase the DVD, and at a later time decide to purchase the rebuild kit, is it possible to purchase it without the DVD? Or should I just go and buy the kit from the get go.

Edited April 10, 2014 by HuD 91gt

[HuD 91gt]

http://www.classiczcars.com/forums/su-carb-technical-articles/29630-nice-link-su-function.html

Doing more research on these carbs. I'm curious if my maybe foolish act of blocking the intake, caused the dashpot dampening oil to be sucked through into the engine. Maybe that is the reason I have no throttle response. I tried check the oil, but I find it very difficult to see the level. Why isn't it dirty like motor oil

[HuD 91gt]

Wow. Topped up the damper now, and I got throttle response once again! Decided to pull the plugs, clean them up a bit and see if that helped things at all. Nothing. So I decided to put new plugs in, and noticed one of the plug wires was a little loose on the end of the plug. Crimped it a little tighter and now it's finally firing on all cylinder! But she is a smokey one. Wow. Tomorrow i'll get her out in the alley and let it warm up. Hopefully it will clear up after it gets running for a while!

[HuD 91gt]

Just want to thank you guys for the help.

Today I got to do a little more work on the car. When I cleaned off the nozzle last time I didn't lube it afterwards. So once again they were sticking. So I cleaned them with carb cleaner, then lubed the nozzle with some light oil. I also sprayed some lithium grease onto the linkages.

After that, I disconnected the fuel hose from the float housing and the nozzle. Sprayed carb cleaner up the nozzle, and into the housing. I also flushed out the lines between the fuel pump and the carbs.

Fired her up, and after a couple little backfires i'm assuming from residual carb cleaner she idled (And revved) like a champ! Next on the list is the brakes. When the brake booster is operated properly, do these brakes feel like a modern car? They are firm, but I am certainly not getting the aggressiveness(Requires much more pressure) I have in my 3 series.

Edited April 14, 2014 by HuD 91gt