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TR4/4A Three Questions: Distributors, Idling, Turn Signal Flasher

KVH

Luke Skywalker
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a) I'm frustrated with the tuning on my TR4A. It was perfect two years ago, but, of course, I changed out the points and condenser and "perfected" it to a worse condition. Nothing I do seems to help. The point gap is perfect, and the timing is spot on. I might try advancing it a bit, but the problems I'm having are: As the car idles, it just keeps dropping RPMs until it stalls. The car won't just idle. It starts at about 1100 RPMs, stays there for 20 seconds, then drops to 400 or so and stalls. I've tried the idle screws, but those don't help. I have to start with a race idle, and then it still drops. I've checked the vacuum line, I see or hear no leaks at the manifolds. The gaskets are all relatively new. The carb spindles also seem fine. Could this have anything to do with the condenser? I also have more preignition than before I tinkered with the points.

b) What is the latest thinking on electronic distributors? Stay with points or go electronic? I'm inclined to keep what I have. I see lots of cheap distributors online. Tempting, a bit anyway.

c) Screwy thing going on with my turn signals, and putting in a new flasher made no difference. My right turn signal is fine, but the left one blinks very fast and sometimes won't blink at all--at least until I first turn on the left signal and then go back to the right. Seriously, if I start left and go right, it seems to work. But starting with the right is always a problem, and at least half the time I get that fast blink like something's very wrong. Is it just a bad bulb somewhere? It seems that years back changing the front bulb fixed everything on a similar problem.

Thanks all
 

bobhustead

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Throttle shafts leaking? Squirt some engine oil around the places where the shafts pass thru the carb bodies (both sides) and see if any improvement. While my experience is only with stock dist., this issue has been punted around the forum and a lot of guys who have tried both like the stock dist. Probably right on the burned out bulb guess.
Bob
 

TR3driver

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Sounds like a mixture problem with idle, to me. Do you have ZS or HS6 carbs? If HS6, I'd be giving the jet centering the hairy eyeball. Make certain the piston falls and lands with a distinct click, preferably with the mixture nuts set a turn or two leaner than their normal position (obviously put them back after checking the centering). The piston also has to move absolutely smoothly through the entire range, no rubbing on the dome. The domes are thin and much more fragile than they look, so it's easy to pick up a dent that causes the piston to bind.

Anything that reduces the current through the flasher can make it act wonky. It's supposed to be to warn you that a bulb is out, but a dodgy connection anywhere can cause problems. I've even heard of the wires corroding inside the insulation enough to cause issues. Don't forget the grounds for the bulbs.
 

NutmegCT

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I'm surprised your idle speed drops to stall only after changing points and condenser. Sure you didn't change/adjust something else? Sounds like a fuel problem to me - maybe the fuel pump can't fill the bowls as the engine slows down. Been there, done that.

Blinkers are often weird because of changing resistance in the wires, and/or incorrect/mismatched bulb sizes (watts/current draw).

Electronic distributors? or electronic ignition (points)?
 
OP
KVH

KVH

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Sounds like a fuel problem to me - maybe the fuel pump can't fill the bowls as the engine slows down. Been there, done that.

Yesterday, I had to pull to the side of the road while my car, on a hot afternoon, starting missing like a plug was shot. I wonder if, instead, it really was the fuel pump. Would that cause the car to sputter and miss, or just shut off? Maybe that plus the erratic idle should make me suspect the fuel pump after all?
 

NutmegCT

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Here's what I'd do to see if it's a fuel pump issue. Let the engine idle until it slows and stops.

Then look inside the fuel bowl(s) and see if they're empty.

Empty = poor fuel flow between pump and bowl
Not empty = something else

Let us know what you find.
 

Toledo_Man

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One possible problem with your points could be timing scatter. This is caused by a worn distributor shaft. The shaft will wobble and the points gap will be all over the place. A new or reconditioned distributor will fix this problem. If you decide to fit electronic ignition, you won't have the problem because it won't be affected by a worm distributor shaft. I have electronic ignition on my Dolomite and it has improved reliability no end. You need to make sure your ignition is 100% before moving on to the fuel system.
 
OP
KVH

KVH

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Empty = poor fuel flow between pump and bowl. Not empty = something else. Let us know what you find.

OK, I haven't lifted the lid on the fuel bowls yet, but are you saying that the floats should be low with the fuel also low? In other words, a marked and obvious lack of fuel volume in the bowls?

Further to the same point, is the following indicative of an issue: My plastic fuel filter looks rather dry. I seem to recall it should look about half full with gasoline. Not so at this time. I barely see fuel in there other than when the car is running.
 

NutmegCT

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OK, I haven't lifted the lid on the fuel bowls yet, but are you saying that the floats should be low with the fuel also low? In other words, a marked and obvious lack of fuel volume in the bowls?

Further to the same point, is the following indicative of an issue: My plastic fuel filter looks rather dry. I seem to recall it should look about half full with gasoline. Not so at this time. I barely see fuel in there other than when the car is running.

Basically, you're right. So let us know the results of the "run til it stops, check the bowls" test.
 
OP
KVH

KVH

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Basically, you're right. So let us know the results of the "run til it stops, check the bowls" test.

Here's the situation: Both fuel bowls at the HS6 carbs are just a little more than one-third full. In other words, when I remove the float and lid, there's about one inch of fuel inside each bowl, maybe a little more. The front bowl is actually a bit lower than the rear. My fuel filter is empty which seems odd since in my other TR4A it's about half full. Does any of that indicate a pump problem? The symptom I'm having is that my idle will never stay steady, and almost always declines over a few minutes, often to a stall. Thanks for the help.
 

NutmegCT

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Here's the situation: Both fuel bowls at the HS6 carbs are just a little more than one-third full. In other words, when I remove the float and lid, there's about one inch of fuel inside each bowl, maybe a little more. The front bowl is actually a bit lower than the rear. My fuel filter is empty which seems odd since in my other TR4A it's about half full. Does any of that indicate a pump problem? The symptom I'm having is that my idle will never stay steady, and almost always declines over a few minutes, often to a stall. Thanks for the help.

OK - so you let the engine run until it quit, and then you measured the fuel levels in the carb fuel bowls, right?

When you say fuel filter, do you mean a glass bowl at the fuel pump? or do you mean a modern clear plastic fuel filter?
 
OP
KVH

KVH

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I let the engine dwindle down to 500 rpms then clutched if off so I wouldn't have 30 seconds of pre-ignition. But, yes, the car was in a downward spiral toward a stall, which has been the norm unless I turn the idle screws way up for 1500 rpms, and even then it gradually comes down lower. By the fuel filter I mean the Moss Motors plastic inline one I use to be sure the gas to the carbs is clean. I don't mean the glass fuel bowl. That bowl was full. Thx for whatever thoughts.
 

NutmegCT

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Now this is getting interesting. It doesn't stall if you've cranked the idle speed way up?

If the fuel bowls still have fuel, and there's fuel in the pump glass bowl, now I'm thinking you have a failing coil. At high engine speed, it puts out enough current to keep the engine going. But as the engine slows down, the voltage is dropping, spark gets weaker, and eventually won't fire at all.

Assuming the carbs are otherwise clean, adjusted and running ok, I'd suggest you change out the coil and let us know the result.
 
OP
KVH

KVH

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I'll put a voltmeter on that coil and see what I observe. What about that fuel filter? Shouldn't there be something in it? It's bone dry when the car is shut down.
 

NutmegCT

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I'll put a voltmeter on that coil and see what I observe. What about that fuel filter? Shouldn't there be something in it? It's bone dry when the car is shut down.

Volt meter probably won't tell you much, as coils usually fail the hotter they get during use.

The plastic fuel filter has fuel in it while the engine is running, right? Depending on the orientation of that filter, you may or may not see fuel remaining in it. They never fill up with fuel - it's usually mostly air. You might try removing the plastic filter and seeing if that fixes the problem. But now I'm betting it's ignition, not fuel.
 

Brinkerhoff

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Fuel in the bowls is a good sign but you need to verify that your float level setting is correct or the engine won't idle right.
 

TR3driver

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The fuel filter certainly seem to indicate some problem; most likely an air leak somewhere. Could be a pump problem, but I'd be looking for a restriction or leak on the suction side or something like that.

What does the engine sound like as the idle is dropping? Does it always miss on the same cylinder (a regular chug-chug-chug) or is the miss more erratic? Can you see any smoke from the exhaust? What do the plugs look like after it has died?

A leaky float valve might cause the mixture to go rich at idle (by letting the fuel level go too high). Same thing might happen if you have a "sunken" float (ie one that has become slightly heavier from absorbing fuel and no longer floats well enough to hold the valve closed under all conditions). Might be interesting to swap floats and see if the front carb then has more fuel in it.
 

TR-3rg

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Hi,

I had a similar problem with my TR-3a. It would idle at 800 rpm, then drop to 400 rpm, then back to 800. Above 800 rpm it was fine. Turned out to be a well worn mechanical advance in the distributer. I hooked up a timing light and the mark was swinging from about 5 advanced to about 10 retarded. I popped the distributer cap off and turned the rotor in one direction and the rotor did not return, I turned it in the other direction and the same thing. I replaced the distributer and all was well.

My old distributer was a Lucas DM2. I believe your car has a Lucas D25. I am not familiar with the D25 so I do not know if it would behave the same way. Anyways good luck!

RG
 
OP
KVH

KVH

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The fuel filter certainly seem to indicate some problem; most likely an air leak somewhere. Could be a pump problem, but I'd be looking for a restriction or leak on the suction side or something like that.

What does the engine sound like as the idle is dropping? Does it always miss on the same cylinder (a regular chug-chug-chug) or is the miss more erratic? Can you see any smoke from the exhaust? What do the plugs look like after it has died?

A leaky float valve might cause the mixture to go rich at idle (by letting the fuel level go too high). Same thing might happen if you have a "sunken" float (ie one that has become slightly heavier from absorbing fuel and no longer floats well enough to hold the valve closed under all conditions). Might be interesting to swap floats and see if the front carb then has more fuel in it.

Thanks for all the help here. I'm really trying to get this car back to like it was when I bought it. Here are some more details based on the questions posed: a) the plugs bother me because they're so dry and brownish/gray. I'm used to seeing them a bit sooty, but maybe it's all correct. I'd rather be rich than lean; b) the chug as idle slows is not irregular, and I have no smoke or oil burning; c) I'll check the floats. I will say this--the fuel squirt when I manually primed the fuel by using the little pump lever really looked anemic. And, like I say the filter bowl is dry. I see no fuel leaks.
 

glemon

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It is fuel delivery or electrical, your points adjustment and timing, if off, would make the car run bad all the time. Sounds like you have indications of fuel delivery problems, I would focus on the pump as others have indicated, or a clog in the system, which will constrict as the fuel pull sucks the debris in, such as at the fuel tank exit. If it is not fuel, I had a bad condenser on a car once that confounded me to no end, the effects were somewhat similar to what you describe.
 
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