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TR2/3/3A TR3 Warm Up Issues

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TR3TomG

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Any thoughts on this issue? My TR3 seems to take a long time to warm up, and the choke is needed for 10 or 15 minutes or so or it sputters a lot on accelaration. Notably, the temp gauge only moves a quarter inch or so and nowhere close to 180 degrees. I just replaced the old thermo with a 180 degree thermo, and no change. I guess the gauge could be an issue (and I intend to check the water temp with some other device (turkey thermo?)), but that would not explain the long warm up time. Oh yeah, I also get what seems like a lot of valve taping. Not sure its at all related and intend to adjust the valves this weekend.

Many thanks for any thoughts.
 
After you do the valves, touch up the mixture as well. Trying to run too lean can cause an apparent long warmup. Also check your dashpot oil. If you are running something really thin (eg ATF), you might try a heavier oil (I use 20 weight).

If the valves are still noisy after you set them, it may be that the rocker tips are worn and giving you a false indication with a feeler gauge (which bridges the wear).

Weather is fairly warm here, and I was still using a touch of choke when I got on the freeway this morning, roughly 5 min after cold start.
 
Many thanks. I toped off the dash pots very recently, and Ill try the other things that you suggest. What is the best/easiest way to make the adjustment to make it less lean? I really appreciate all the wisdome and help that knowledgable people like you are willing to share with novices like me. It makes having and keeping these old cars a lot easier and enjoyable, though I must admit, I may be running thin on patience with the car.

Thanks again.

Tom
 
My preference is the old "lift the piston" test, as described in the owner's manual. Basically you lift the air piston a small amount (roughly 1/8") with the engine idling and listen to what the idle rpm does. If the rpm rises and stays up, the mixture is too rich. If the rpm falls immediately, the mixture is too lean. If the rpm rises a bit and then falls back to where it was, the mixture is just right.

When everything else is right, this test is very sensitive. There should be no more than 2 flats (1/3 turn) of the mixture nuts between "too rich" and "too lean" ... usually I can tell the difference for even 1/2 flat (1/12 turn). If turning the mixture nut doesn't seem to make much difference, chances are that there is a problem somewhere else (valve lash, ignition timing, carb synchronization, etc)

You can remove the air filters and use a small screwdriver to lift the pistons. This method is probably best at first, so you can see how far you are moving the piston. But there should also be a "lifting pin" on the side of the carb body near the float bowl, which you can use to lift the piston without removing the filter.
 
Well in some respects having the longer and colder war up is a good thing because it indicates you are not running rich. A rich running vehicle will move out quicker but will contaminate the oil with fuel which can lead to bad oil rings. Do some searching on the forum about chokes because the tr3 has a problematic choke system. The case might be that your choke is not working very well at all and the spurting would lesson and the engine might warm up better if the choke was functioning proper. My suspicion is your gauge is off. One thing about tr3s they usually run very warm. Again check/search the forum for cooling fans and radiators. See if you can find a Haynes Manual for tr3, they might be in print. It has a good section on setting tappets. However, there is one typo in the setting sequence chart, but if you look at the information for a minute you will understand the typo. Moreover, when I set tappets and points and stuff like that I usually remove the spark plugs, it just makes thing easier to move.
steve
 
TR3driver said:
My preference is the old "lift the piston" test, as described in the owner's manual. Basically you lift the air piston a small amount (roughly 1/8") with the engine idling and listen to what the idle rpm does. If the rpm rises and stays up, the mixture is too rich. If the rpm falls immediately, the mixture is too lean. If the rpm rises a bit and then falls back to where it was, the mixture is just right.

Randall, what's the theory here? Raising the piston without cracking the throttle should be letting more fuel in with no additional air. An increase in idle would be curing a lean condition. I know you're quoting the owner's manual (I just read the same in mine) Why do you think this works this way?
Click to expand...
 
bnw said:
Raising the piston without cracking the throttle should be letting more fuel in with no additional air. An increase in idle would be curing a lean condition. I know you're quoting the owner's manual (I just read the same in mine) Why do you think this works this way?
Click to expand...

Raising the piston opens the jet a bit, but also increases the size of the venturi and with the same air flow, will decrease the depression (which pulls the fuel out of the jet).

Still don't know how that explains it, though.
 
I believe Darrell is on the right track. Larger opening = lower velocity = less depression = less fuel. It also increases air flow just a bit. So the rpm rises because of the extra air and then drops because of the leaner mixture (it takes a moment for the fuel to slow down flowing through the jet once the depression is reduced). When the two effects are equal, the mixture is just what these carbs are designed for.

Or I could be talking through my hat. That's just what I think.
 
TR3driver said:
Larger opening = lower velocity = less depression = less fuel.
Click to expand...

It took me many years to finally figure this all out. I always used to think we wanted thinner oil in the dampner, so that the piston would rise faster and open the jet and let in more fuel (since there isn't a acceleration pump). But it actually works the opposite way, you want the piston to lag the actual air flow, which creates a larger depression, and pulls more fuel into the mixture, despite the jet still having a smaller opening.
 
Prezactly!
 
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