Idle problems - 69' 510

[Wesglock]

My 1969 510 has roughly 67k and sports the original carb with glass window. She'll start and run if I pull the choke a little and provide extra gas from the pedal. She'll stay running after pushing the choke back in only if I keep giving her gas via the pedal. The previous owner thought that she needed carb work. I'm not sure where to be begin. I've thought about replacing the carb with a weber but if it''s just a simple matter of trouble shooting the original carb then I'd be greatful for any pointers on where to begin.

 

Cheers

[Stoffregen Motorsports]

I'll let someone else explain the carb tuning, but I thought I'd offer my opinion on Weber vs stock carb. The car (if that's the car in your avatar) looks super clean and original. It's not every day you see a clean original. Weber DGV's run great, but you will have to tune that carb too, so either way, you're into it for some labor.

 

I say leave it stock.

[Wesglock]

I'll let someone else explain the carb tuning, but I thought I'd offer my opinion on Weber vs stock carb. The car (if that's the car in your avatar) looks super clean and original. It's not every day you see a clean original. Weber DGV's run great, but you will have to tune that carb too, so either way, you're into it for some labor.

 

I say leave it stock.

 

Thanks for the feedback regarding the stock vs Weber carbs. In all honesty, I know that I need to do more research and aquire several books including the service manual. I'm not even sure where the mixture and speed adjustments are located on this carb. Maybe some could post a link or post some basic steps for carb tuning an original 69' carb.

 

Thanks in advance!

 

Cheers,

Wes

[banzai510(hainz)]

this are simple cars.

the mixture is at the base of the carb on the the valave cover side and will have a brass tensiopn spring.

you can try turing this IN/OUt and see if its better. count the turns incase you have to go back to the org posisiton if that dosent help.

Could be a pluged idle jet.

One way to tell is replace the fuel filter and then cut it open. it alot of rust and dirt then most like it could be a plugeged idle jet.

Im not a stock carb expert anymore as I threw them away after they wear out. Webers are just Ezer to maintain for me.

 

One can do a Mexican tune up Rev the shit out of the carb and put a Rag over it and maybe by chance it suck the dirt out of the jet.

[kelowg]

Another on stock carb,if u remove fuel bowl window. DO NOT OVERTIGHTEN. It well break

[kelowg]

And most likely needs a rebuild.

 

. Not to hard,just go slow. Remove each part clean and replace. People tend to blow it all apArt and cant remember how it was together.

[ggzilla]

When you pull the choke knob out, it increases the idle speed.

When you give it a little gas, it also increases the idle speed.

 

>She'll start and run if I pull the choke a little and provide extra gas from the pedal. She'll stay running after pushing the choke back in only if I keep giving her gas via the pedal.

 

The carburetor needs adjustment, not rebuilding.

1. Start with the float level. If when idling, it is near the line on the glass cover, it is good.

2. Next turn the idle speed screw in one turn clockwise. Will it run without the choke now, after fully warming up?

3. Adjust the speed to 750 RPM, then adjust the mixture screw for best lean idle.

[racerx]

maybe this will help..http://www.carpartsmanual.com/datsun510/Datsun510Index/Engine/Carburetor/L16Auto/FromJul72/tabid/501/Default.aspx

[Wesglock]

Thanks for the quick replies. I've made some progress. After adjusting the idle screw it now idles with alittle choke. I was so stoked it actually remained idling that I drove around the block. It stunk up my whole neighborhood, people were walking their dogs giving me the sink eye...I just laughed. I'll work on getting it toddle without choke but I agree that cleaning is probably inorder.

[Wesglock]

When you pull the choke knob out, it increases the idle speed.When you give it a little gas, it also increases the idle speed.>She'll start and run if I pull the choke a little and provide extra gas from the pedal. She'll stay running after pushing the choke back in only if I keep giving her gas via the pedal.The carburetor needs adjustment, not rebuilding.1. Start with the float level. If when idling, it is near the line on the glass cover, it is good.2. Next turn the idle speed screw in one turn clockwise. Will it run without the choke now, after fully warming up?3. Adjust the speed to 750 RPM, then adjust the mixture screw for best lean idle.

 

Still not quite sure where the mixture screw is. Waiting for the service manual to arrive amazon, hopefully it will have detailed exploded view.

[Wesglock]

maybe this will help..http://www.carpartsmanual.com/datsun510/Datsun510Index/Engine/Carburetor/L16Auto/FromJul72/tabid/501/Default.aspx

 

Yes, this did help. I was able to verify the location the idle set screw. However, still not sure where the mixture set screw is....??

[Wesglock]

.One can do a Mexican tune up Rev the shit out of the carb and put a Rag over it and maybe by chance it suck the dirt out of the jet.

 

LOL!

[datzenmike]

The idle mixture screw is just to the right of the base of that spring in the picture below.

 

The idle speed screw is just to the left of the middle of the spring. Has some rust on it.

 

[racerx]

when you do turn the screw, you don't need to turn that much, maybe 1/8 of a turn at a time and listen to your RPM.  Always remember how many turns you did or else you can get lost. good luck...not sure if you have a book yet, but maybe this is a good time to get one.  I have a 32/36 weber and I am fairly sure tuning the carb is similar. After you have made the adjustment, you can check your spark plugs and see if it's burning okay. If the spark plugs are too soothy and black then it's running too rich. This is why it's important to have a reference point of where you started...good luck. 

[datzenmike]

I find on the Hitachi that there is about 1 1/2 to 2 turns on the mixture screw between the in (lean) and the out (rich) position. Past these points the RPMs change to a stumble but between it is fairly even. Just set halfway between is good enough. You're looking for the smoothest fastest idle speed and when the mixture is right it will smooth out noticeably. By now the idle has gone up and needs to be turned down on the idle speed screw. The trouble now is that the throttle plate has closed slightly and the manifold vacuum is probably higher and your idle mixture has changed. So turn the mixture screw in and out looking for that sweet spot where the idle quality is smoothest and fastest. Turn the idle down and repeat until you can't make any improvements and the idle is 750-800. You may have to do this 4 or 5 times but it takes what it takes.

 

Don't even think of wasting your time doing this if your valves have not been set correctly and your timing set. Always do that first.

[Buzzbomb]

Two things worth having while working on ANY old car..A Tach/Dwell Meter AND a vacuum gauge. Both are super useful when tuning idle mixture/speed. If you plan on keeping the car, it's a worthwhile investment, IMHO.