Just can't seem to get my car to idle well.

[5casey1dimer0]

Hello all, I don't post here much, but seek answers here often. I drive a 72 510 with a stock L16, stock carb, stock everything. I have gotten used to my car not idling. When i come to a stop I feather the gas to keep it running. Today I put a new thermostat and a aftermarket coolant temp gauge in my 510. Since I was working on the car I decided to give fixin my idle a shot. I adjusted the Idle the fuel mixture. I got it to idle, well choppy i guess. with the car in drive, and the parking brake on, I got it to idle at 700-ish rpms.

 

Next I checked for vacuum leaks. I could not find any hoses that were cracked and or split. Everything appears good. But, I could not feel any pressure from the vacuum advance hose off the distributor. To add to that, there seems to be a lot of vacuum in the crank case. I put my finger over the valve cover breather the car idled significantly better, and well, I am stumped from here.

 

Any ideas or input for me?

 

Thanks in advance,

[metalmonkey47]

Hm... just my $0.02, I don't think you should have any vac pressure at the advance around idle. It pulls vac pressure from below the throttle plate (I think) so the only advance you would have is above idle. Wouldn't really work very well if you have your timing advanced 24/7. Check your idle jet and make sure it's not clogged.

[DISLEXICDIME]

see if you can snug up your carb bolts where it mounts to the manifold i have had thwm come loose. grab the top of the carb and see if it moves the stock hitach has to bolts holding the upper and lower halves together some times the bolts get loose the only way to tighten them is to take the carb off and tighten them from the under side

[DISLEXICDIME]

o yah pull your plug wires off one at a time see if it idols different each time you take one off are your points adjusted right . are the points dirt hows your cap and rotor any cracks in the cap how are your plug wires what are the plugs gaped at?

[5casey1dimer0]

Thanks metalmonkey and dislexic, both make good sense. I'll check it out after work tomorrow.

 

Plug wires, cap, and rotor all look great as they are fairly new.

 

I'd also like to ad that my car runs great when moving only is choppy at idle and I need to feather the gas taking off from a start.

 

Thanks again!

[DISLEXICDIME]

remember when you adjust the carb you should adjust your timing .

[5casey1dimer0]

I briefly played with the timing today, tomorrow I will get a timing light in there as well as checking the carb bolts as stated earlier.

[datzenmike]

Valve lash and timing must be set before messing with the carb. Timing can be adjusted by slightly loosening the adj. hold down bolt so it can be easily twisted by hand while out on the road. Adjust till it idles smoothly and take for a drive. Advance it slightly by turning the dizzy clockwise. Keep adding advance until there is noticeable ping under load then turn counterclockwise slightly to get rid of it.

 

It's normal to have vacuum in the crank case.

[5casey1dimer0]

Valve lash and timing must be set before messing with the carb. Timing can be adjusted by slightly loosening the adj. hold down bolt so it can be easily twisted by hand while out on the road. Adjust till it idles smoothly and take for a drive. Advance it slightly by turning the dizzy clockwise. Keep adding advance until there is noticeable ping under load then turn counterclockwise slightly to get rid of it.

 

It's normal to have vacuum in the crank case.

 

that's what I used to do with the old ka-e in my 240, adjust drive and repeat untill it felt good. What's the "ping" you talk about under load?

[DISLEXICDIME]

Valve lash and timing must be set before messing with the carb. Timing can be adjusted by slightly loosening the adj. hold down bolt so it can be easily twisted by hand while out on the road. Adjust till it idles smoothly and take for a drive. Advance it slightly by turning the dizzy clockwise. Keep adding advance until there is noticeable ping under load then turn counterclockwise slightly to get rid of it.

 

It's normal to have vacuum in the crank case.

 

o yah i forgot about that make sure your valves are adjusted right it makes a world of difference.

[dennis]

I had a similar situation, my issue was with the PCV. To test if is not working correctly just block the PCV below the carb on the manifold toward the firewall. Turns out my PCV was missing the ball inside of it.

[5casey1dimer0]

I had a similar situation, my issue was with the PCV. To test if is not working correctly just block the PCV below the carb on the manifold toward the firewall. Turns out my PCV was missing the ball inside of it.

 

See I should have checked this too, I over looked something that should have been first instinct to check. Thanks!

[Nicholas7620]

I have the same ongoing problem, :blink: I've tightened up my carb after finding the nuts had come loose on the outside of the carb, I never knew you could tighten the carb from the bottom of the carb. :o

 

I've traced my prob to bad floats in my carb and ordered a newly rebuilt carb from NationalCarburetors.com for $220. I haven't received the carb yet.

 

I also replaced nearly all my vacuum lines because it was inexpensive :P and some of the hoses had calcified and were hard as a rock. :)

 

I received links to great websites from DGuy210 and GGZilla. :D

 

Here they are 1) http://datsun1200.com/modules/mediawiki/index.php?title=Float_Level_Adjustment

 

 

2) http://datsun1200.com/modules/mediawiki/index.php?title=Carburetor_Adjustment

 

I've had problems with my Datsun not idling of and on for about two years plus. I was able to make the problem intermittent and go away for weeks at a time. But now it's constant hence my ordering a newly rebuilt carb.

 

You can check out all the replies I received during the course of the last couple years.

 

http://community.ratsun.net/topic/7222-carburetor-problem-pictures-help-wont-idle/

 

The ratsun forum has taught me almost everything I know about carburetors, or course studying the shop manual also helped. ;)

[5casey1dimer0]

Well, I want to thank you all for your help. I finally got around to doing some more tinkering on the 510. First off I started off by taking out the PCV valve. It was pretty gunked up, I cleaned it up, and noticed some more movement out of the little ball inside, then stuck it back in. I did order a new one, but the schucks still hasn't received it. I really dislike schucks, nothing but problems from them, but it is half the distance to napa from my place. second I played with the carb a little more and got it to run without assistance of me feathering the gas. Once again, it ran "choppy." Next I checked again for vacuum leaks, still couldn't find anything.

 

After checking to make sure the carb was tight to the manifold as mentioned in a previous reply, I checked the points, plug wires and plugs. All looked good, there was very minimal corrosion on the points which was easily scraped away with my finger nail.

 

As a final check, i pulled each plug wire one by one. #1, 3, and 4 obviously made the car idle different. I couldnt really tell upon pulling #2 because the car idles so choppy to begin with. I rechecked all 4 and still cant tell on #2. I feel like my mind is playin tricks on me because i am suspicious of it. But I do hear a little snapping when the plug wire is being held over but not on to the end of the plug. I know the plug wire is good.

 

I also want to add that when i was messing with the carb I noticed that if I put my finger over the breather on the valve cover the engine would rev up probly around 1000 rmps, and if I held it long enough, 30secs to a minute, and released it you can really feel the vacuum suckin on my finger and then the engine will cough a few times and die within seconds. I don't think this is normal.

 

I appreciate everybody's help and input, I don't know a whole lot to do with the L series, or even just an older carbureted engine. First engine I ever really did much to was my sr in my s chassis. silly that i understand more with all the tps sensor, mafs, coilpacks and such, but am stumped on such a simple engine in the Datsun. Even though my problem with the car is frustrating, I am enjoying learning and working on it:)

 

More input please and thank you!

[datzenmike]

Valve lash and timing must be set before messing with the carb.

It's normal to have vacuum in the crank case.

 

 

o yah i forgot about that make sure your valves are adjusted right it makes a world of difference.

 

Important to check this. A tight exhaust will leak and act like a dead cylinder. Just wiggle the rockers one at a time when the cam lobe is in the up position. As long as it wiggles a bit it's good. If you find a rocker that is tight, adjust it.

[5casey1dimer0]

Important to check this. A tight exhaust will leak and act like a dead cylinder. Just wiggle the rockers one at a time when the cam lobe is in the up position. As long as it wiggles a bit it's good. If you find a rocker that is tight, adjust it.

 

will do, tomorrow! Thanks again!

[DISLEXICDIME]

you should make a video of your car running and post it

[Nicholas7620]

At least you are idling now with out having to feather the gas. You are making small improvements. It will be interesting to see if your problem completely goes away after you install a new PCV valve. :rolleyes:

[5casey1dimer0]

you should make a video of your car running and post it

 

yeah i can do that, will probly bee a cell phone video though, my flip video recorder went haywire.

[DISLEXICDIME]

check your plug gap