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Heat Shield - will it solve my problem....

Gliderman8

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... of stumbling/hesitating/not being able to accelerate when hot?

When I take my TR6 out after sitting all night, I have full power and can accelerate with no problem. After it warms up say 20 mins or so engine will hesitate/stumble upon acceleration. I had Jeff at Advance go over my dizzy so I'm pretty certain all is in order with it. I do have pertronix ignition but I would think it would either work or not work. The problem only arises when it gets hot.
Could the carbs/fuel be getting too hot? (using stock ZS carbs)
Will installing a heat shield alleviate this problem?
 

poolboy

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Well, Elliot, it does get awful hot down here and I have put heat shields on both of my TR6's, but it wasn't because of the symptoms you describe, rather it was because a hot engine was hard to restart.
My theory is that as long as the engine is running, the fuel doesn't sit in one spot long enough to heat up to the point of percolation. When you kill the engine, the gas just sits there soaking up the exhaust manifold heat.
Still might be fuel problem in your case though. Maybe too rich mixture, either from the needle adjustment, the float level or a sticky float chamber needle valve.
Carb related, that's all I can think of.
Fuel related, maybe the fuel filter needs changing, or the gas tank vent is blocked
Ignition related...coil ?
 
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Gliderman8

Gliderman8

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Ken- All good info.... I have no problem starting a hot engine. Coil?.... would it "act up" after getting hot? I mean I still have ignition. That's why I was leaning towards hot fuel. I do think it is realated to fuel and not ignition.
Hummmmm..... :wall:
 

DNK

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Anything electrical is usually exacerbated with heat,am I right here guys?
 

poolboy

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Well yeah, heat does raise the resistance to current flow, and current flow does create heat.
I was thinking the coil though because I once asked someone who should know more than me about a coil acting up. It always seemed to me that like most elecrical stuff it either works or doesn't.
But I was told that (with an imperfect coil) due to heat, internal coils can expand, and make contact with another part of the coil, in effect reducing the number of windings, thus reducing the voltage.
I mean I can visualize something like that and I do have to respect the knowledge of the mechanic who told me, so I guess it's possible for a coil to be somewhat sporadic,while heating up and cooling down.
 

poolboy

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I don't know Elliot, something like that has so many possible causes; it's going to be a process of elimination.
If you have a coil, that's easy to change.
A fuel filter is easy to change and may prove not be heat but running time related.
Perhaps the carb mixture should be leaned, keeping track of the adjustment so you can return to the starting point if that's not the culprit.
I'm guessing you made sure the choke is all the way off because once the engine heats up an engine with a little choke left on will run rough.
That's the easy stuff that I can think of checking..one thing at a time of course.
 
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Gliderman8

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Choke is definitely off. Fuel filter... it's been in about two years and tank was cleaned and sealed so no little crud in the tank.
Will start trying some of the suggestions.
 

TR4nut

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I'm thinking coil - had that problem about 30 years ago.. yes they can act up when they get warm.
 

TR3driver

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A 73 TR6 would have a resistor wire incorporated in the harness wire to the coil. Is your Pertronix wired so the red wire gets a full 12v instead of from the resistor wire? And do you have the proper "external ballast required" coil, or the resistor bypassed for the coil?

If the wiring is right, then trying a "known good" coil would be a good next step, IMO.
 

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poolboy

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As long as he's getting at least 8 volts from the ballast resistor wire, he won't really need to bypass the resistor wire with the pertronix red wire.
I really believe that those instructions and ilustration are not TR6 specific.
PERTRONIXvolts.jpg
 
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Gliderman8

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Will check my wiring in the morning... if I need to get a new coil what do I need to know since it has the ballast wire in the harness. Can I pick one up at my FLAPS?

edit: will also check the voltage to the coil as well.
 

poolboy

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Sometimes a PO will have changed the wiring to the coil to bypass the ballast resistor wire. So what you need to do is verify that you have the original 2 conjoined wires going to the coil. They will exit the harness behind the alternator and connect to the spade on the + terminal of the coil.
The wire with the braided cloth sheath will be the ballast resistor wire that supplies between 9 and 10 volts to the coil when the key is in the "ON" position. The other wire supplies 12 volts to the coil only when the starter is engaged. At least that's the way it's supposed to be.
If you have that set up and want a replacement coil for testing, get one with a 1.5 or 1.6 ohm resistance.
You may have to get the male spade connectors to put on the coil. A lot of times there are just threaded terminals with nuts for eyelets, but spade adaptors are available..Try NAPA if nowhere else.
 
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Gliderman8

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Thanks Ken... I will be doing some investigating of the wiring tomorrow!
I appreciate all the help.
 

JerryVV

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Have you eliminated the engine driven fan and replaced it with an electric fan? If you have and are driving in stop and go traffic you will build up a lot of under hood heat that may not be being moved if the fan has not come on. One of Joe's Heat Shields will help.
JVV
 

71MKIV

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zip lock baggie, full of ice, pack it around the coil, see if problem doesn't show up.
 
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Gliderman8

Gliderman8

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71MKIV said:
zip lock baggie, full of ice, pack it around the coil, see if problem doesn't show up.
Interesting thought... my luck, it will leak and short things out!
Think I will invest in a new coil to see if the problem goes away.
 
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