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TR2/3/3A Are these Knackered?

RobbieP

Freshman Member
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I've been trying to get his Tr3A running and I've got fuel and spark, however it still won't turn over. I cleaned out the carbs and set them to SU specs, (12 flats ) Still nothing. I noticed the pistons in the carbs are very loose and drop quickly. Is that normal? I've taken a video..

https://www.youtube.com/watch?v=4da52yKunG8&feature=youtu.be


Are these knackered? Or can I rebuild the jets to fix the problem?

Thanks!

Rob
 

NutmegCT

Great Pumpkin
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Rob - might help to share more details.

You say it "won't turn over". That means the starter isn't working (starter is what turns the engine over).

Is that what you mean? The engine doesn't even move ("crank") when you try to start it?

Thanks.
Tom M.
 
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RobbieP

Freshman Member
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Rob - might help to share more details.

You say it "won't turn over". That means the starter isn't working (starter is what turns the engine over).

Is that what you mean? The engine doesn't even move ("crank") when you try to start it?

Thanks.
Tom M.

Hi Tom,

It will turn over, so it's not the starter. It just won't fire up. There is spark at the plugs and fuel is being delivered to the carbs, but won't fire up.
 

NutmegCT

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Hi Rob - until folks with more experience comment here, first thing I'd do is try starting for a few seconds, then shut off ignition.

Then pull out a spark plug and see if it's wet with fuel, or dry.

Let us know what you find and that'll help guide us.

Tom M.
 

jimstr4

Senior Member
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When that happened to me it turned out to be the timing.
I have an electronic dizzy so didn't want to use the static timing method and blow my dizzy up.
My friend turned the dizzy as I cranked the starter over and when he got to the sweet spot it fired up.

1962 TR4
 
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RobbieP

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Hi Rob - until folks with more experience comment here, first thing I'd do is try starting for a few seconds, then shut off ignition.

Then pull out a spark plug and see if it's wet with fuel, or dry.

Let us know what you find and that'll help guide us.

Tom M.

I did have a look, they were dry.
 

CJD

Yoda
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When you lift the pistons, you should be able to see the fuel in the jet, about 1/16” or so below the top level of the jet. I suspect you don’t have fuel there...but let us know.
 

TR3driver

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FWIW, your piston video looks fine to me. The damper has a one-way valve in it, so the piston is supposed to fall much quicker than it rises. And you should be able to get it to fire pretty much no matter how badly the carbs are worn. For cold starting, the jets should be lowered quite a bit, not against the mixture nut (so adjusting the nut should have no effect).

Two things that often get recalcitrant engines started for me :
1) Take the plugs out and heat the tip with a propane torch, until there is no more yellow in the flame. Any yellow is carbon burning off the tip of the plug, and carbon can present a path to short out the spark. Obviously hold the plug with pliers or similar during the process.

2) Shoot a healthy dose of spray carburetor cleaner (rather than "starting fluid") down each carb throat and then immediately crank the engine. If it runs for a second or two and then dies; you've got some kind of fuel delivery problem. Could be a blocked fuel passage, or bad fuel in the carbs.

But if it won't even sputter, more likely it's an ignition problem. It takes more voltage to fire a plug under compression, so having a spark jump the gap outside the engine doesn't always mean the ignition is fine. As noted, timing is important too. If all else fails, double-check that you're getting a spark when the cylinder is at (near) TDC between compression and power strokes. As I learned the hard way, they won't run if the spark is at TDC between intake and exhaust :smile:
 
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RobbieP

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When you lift the pistons, you should be able to see the fuel in the jet, about 1/16” or so below the top level of the jet. I suspect you don’t have fuel there...but let us know.

There is a small amount of fuel there, and more there when the choke is out.
 
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RobbieP

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FWIW, your piston video looks fine to me. The damper has a one-way valve in it, so the piston is supposed to fall much quicker than it rises. And you should be able to get it to fire pretty much no matter how badly the carbs are worn. For cold starting, the jets should be lowered quite a bit, not against the mixture nut (so adjusting the nut should have no effect).

Two things that often get recalcitrant engines started for me :
1) Take the plugs out and heat the tip with a propane torch, until there is no more yellow in the flame. Any yellow is carbon burning off the tip of the plug, and carbon can present a path to short out the spark. Obviously hold the plug with pliers or similar during the process.

2) Shoot a healthy dose of spray carburetor cleaner (rather than "starting fluid") down each carb throat and then immediately crank the engine. If it runs for a second or two and then dies; you've got some kind of fuel delivery problem. Could be a blocked fuel passage, or bad fuel in the carbs.

But if it won't even sputter, more likely it's an ignition problem. It takes more voltage to fire a plug under compression, so having a spark jump the gap outside the engine doesn't always mean the ignition is fine. As noted, timing is important too. If all else fails, double-check that you're getting a spark when the cylinder is at (near) TDC between compression and power strokes. As I learned the hard way, they won't run if the spark is at TDC between intake and exhaust :smile:

thanks, I'll give it a try. The spark plugs are new actually.
 
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RobbieP

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Because you are looking down the throat of the carb, I would say that you MIGHT be able to see fuel in the jet. If you remove the piston and covering dome, which includes the needle you then can look from above and down into the jet and see the fuel.
I have rarely been able to see the fuel in the jet from the side view.

I did have the pots off of it, reinstalled them before tI took the video
 

TR3driver

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I did have the pots off of it, reinstalled them before tI took the video

This is not the immediate problem; but something to think about later : At least on my carbs, the fit between the dome & body is loose enough that to R&R the dome upsets the needle centering. You might want to recheck that after getting it running.
 
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RobbieP

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It's time for ... The Question!

When did the engine last run well?

What changes were made after that?

Tom M.

It ran about 5 months ago, but very rough. I did the waterpump(whch I always do when I buy a new project), radiator(had a few pin holes), plugs and cleaned the carbs out, set them to SU specs. The rest of the work was cosmetic.
 

DavidApp

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I used some 1/4" plastic hose to shoot a drop of gas into both carbs on my newly rebuilt engine and cranked it. It fired and ran for a few seconds. That was all I wanted to prove the timing was correct and to see it run for the first time in 20+ years.

David
 

CJD

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There's spark at the plugs, I used an inline spark tester

Since you do have fuel at the jet, you must have fuel in the cylinders. Try David's idea of adding a little fuel at the carb. If still no fire, then...as suggested above...it's time to re-check the timing. Check both the cam and ignition timing.
 

sp53

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It ran 5 months ago and there is spark at the in line tester. I do not know what an inline spark plug tester is; I test them at the plug by pulling the plug and grounding the tip to the head then turn the engine over and watch the spark and examine the plug. Most times with tr3s when they do not start the plugs are fowled with carbon or fuel and they will not start. Pull the plugs put some new clean ones gapped at .25 in and it will run---vooodooo man
 

mt10flyer

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Robbie,
Did you per chance remove all the spark plug wires at once during the installation of the new plugs? The firing order is 1-3-4-2 but the rotor goes counterclockwise. If you have it backwards it will still show spark but at the wrong moment. Thought numder one.

Thought number two - check your oil level and make sure there is not a bunch of fuel in it now. If so, you will want to check the floats and needle valves. You could be flooding it and the fuel has no where to go but into the sump.
 
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