81 fed 210 idle...too much vacuum? timing?

[81sunnyson]

still sorting out issues with idle and rpms.  im revving 5500 6000 rpm just to keep up in traffic.  why am i revving so high? clutch is not slipping. could it be the a15 and the h145 axle gearing? timing or vaccum advance?  it wasnt always like this...i first had symptoms of overcooling, and the radiator would barely get hot

 

either way i have my idle set between 1800 2500 rpm, cold and once it warms im in the 2500-3500 range depending on the vacuum and if the carb gets stucks.

 

 

still tinkering with air cleaner and stock hitachi carb....the same issue with stock air cleaner or spectre carb hat and filter

 

if i adjust the fast idle screw clockwise, i loose brake pedal firmness and the brake pedal almost goes to the floor.

 

so im back to idling rather high, anything less than 1500 rpm cold on my tach the car will stall out or stall when i hit the brakes. 

 

i switched my ignition coil to own i found off an early 80's mitsubishi truck and dropped the rpms down 1000 at highway speeds. now at 4500 5000 vs 5500 6000rpm...still probably too high but better

 

i looked at the plugs and i could probably go to a colder plug. with gas treatment, the plugs get fluffy like a powdered donut

warm days the engine will "diesel" a little after i turn off the ignition. 

hope i dont have detonation, though it does burn oil and the valves are suspect. 

after highway driving the # 1 plug had oil on it.  all vacuum hoses air intact, egr system in tact

 

the egr helps to prevent detonation so i left that and all the vacuum lines are hooked up though not sure correctly. 

 

the only thing different from the eqaution would be the air temperature sensor and air induction pipes not being in the loop

if i drive for a while with the air pipes capped, condensation gets in and then the car will sputter and stall on highway so they are open and the car sounds like a harley

 

the vacuum valve on the stock air cleaner helps the carb adjust with the temperature...but not including either

[ggzilla]

> why am i revving so high?

 

Good question. Why are you revving it so high? And why do you have an H145 in your Datsun 210?

[ggzilla]

> if i adjust the fast idle screw clockwise, i loose brake pedal firmness and the brake pedal almost goes to the floor.

 

 

haha. Brake booster has gone bad. To test it, remove the brake hose from the intake manifold and plug the fitting on the manifold. Carefully drive it, the brakes will still work but you'll have to press harder. Lower the idle speed and put the mixture screw back where it should be.

[81sunnyson]

i pulled the booster hose off( one running to carb) and the hose whisltes loudly.  the brakes work but pedal is super firm and too risky to drive at speed. 

 

should i adjust the dashpot?

[81sunnyson]

_{if i turn the idle mixture screw to clockwise is that lean or rich? i have it backed off two turns from that}

 

_{the booster as told by the brake technican is ok.  plus it would be firm with the hoses on too}

 

_{my pads are low but i had the issues when i put the fresh pads on.  i adjusted the rear shoes and bleed the brakes.  pedal was fine until i messed with the fasr idle screw.}

 

_{the repair  manual says i can adjust the choke index but not sure if that will affect idle}

 

_{i just want to sort this out before it gets hot}

[81sunnyson]

as far as the rear end, it is what ever came with the original a12 and 4speed....that is now with a a15 and dogleg

[ggzilla]

So when you remove the booster hose and cap the engine fitting, it runs much better? Then your booster is bad. Replace it.

 

With the hose fitting plugged, you can now adjust the warm idle speed and idle mixture. Follow the direction in your repair manual. Don't adjust the dashpot unless it is not allowing the idle speed to drop to normal. Do all adjustments with the engine fully warm.

 

Do not adjust the speed screw or mixture screw to a certain number of turns. Use the procedure in any service manual. Set the idle to 750 RPM, the screw out the mixture screw until it starts running badly. Screw it back in a bit and reset the idle to 750 RPM. Then screw the mixture screw in until it just starts to slow down.

[datzenmike]

Your secondary is stuck partly open. Revving that high there is likely less manifold vacuum so the booster isn't working so well.

 

Get a flash light and look down the other barrel. The throttle plate should be completely closed.

[LeviGideon]

Sometimes your chokse can get stuck causing your car to run rich and idle high. Make sure it isn't stuck, mine was adjusted too far closed, and would get stuck. I adjusted it back to the center mark and haven't had a problem since.

 

Make sure your carb is sealed up tight. if you push down a little on the carb and it runs smoother, you've got a leak on the carb (or at the manifold) that needs to be sealed up. My carb got a leak between the choke and throttle chambers recently and it took a while to figure out...

 

Make sure your ignition system is in good condition, as well. The hotter the spark, the better. I'm currently running my coil (MSD Blaster 2) directly from the battery through a relay, and it burns fuel a lot more efficiently.

 

The little things really add up sometimes.

[ggzilla]

We are all guessing.

 

SunnySon, you need to test this. Does it run better with the booster hose plugged? That's a better question than whether the booster works or not.

[datzenmike]

still sorting out issues with idle and rpms.  im revving 5500 6000 rpm just to keep up in traffic.  why am i revving so high?

 

Are you using a tachometer or is this an estimate?

[81sunnyson]

yes using a tach...also using a coil from early 80's mitsubishi/plymouth arrow truck...1000rpm lower at highway speeds

 

sometimes the tach is erratic around 6000rpm even off the throttle.

 

it did run better without the booster but not well enough to have normal idle...but an improvement

 

the carb acts worse after i get off the highway...like it is stuck.  it will be @ 4000 -4500 rpm dead stop and i see smoke out the tail pipe.  so i drive off slow and then brake and shift once im right at the point of stalling to quiet it down

 

i dont have a filter on the fuel line directly @ carb but i checked the line and seemed unclogged.  new fuel filter on the side of the engine

good fuel pressure at gas cap

 

the accelerator cable got stuck once and later slipped off. i realigned the cable

 

fuel level in the glass bowl is visible

[ggzilla]

If there was any improvement it means your booster (or the hose in between) is leaking. Keep it disconnected while you adjust the carburetor down to the correct speed. I worked a a car last summer with that same problem. A good booster will not change how the engine runs.

 

It's not clear from your comments -- are you revving the engine this high by pressing on the gas pedal? Or is the engine revving that high all by itself?

[81sunnyson]

without the booster hose on the carb, it whisltes.  if i put my thumb on the hose, it stalls.  i can lower the idle speed down about 1000rpm or so but no where near 800rpm.  1000-1200 it is barely running.

 

so booster/ vacuum is an issue

 

could my timing or timing chain be an issue?

 

could use a new distributor cap too (coil hole slightly deformed/ melted)

 before i switched coils also had a oil leak at base of distributor

 

running autolite plugs

[ggzilla]

Uh, that is a problem. The brake booster connected to the carburetor will cause all sorts of problems.

 

Brake booster is supposed to connect to the intake manifold. And when you disconnect the hose from the intake, the fitting must be capped to prevent a massive vacuum leak.

 

 

By the way, Autolite plugs are fine. I've run them for years.