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I have a '76 TR6 with 30,000 miles. It sat for several years prior to February of this year. When I acquired it the car was missing and stuttering very bad below 2000 rpms. I had some carb service done and the electronic ignition adjusted by excellent local mechanics in February and the car ran fine. The car has been slowly regressing and when fully warmed up and after running for 15-20 minutes is now missing and stuttering again below 2000 almost as bad as before. Are the carbs so fouled from sitting without proper storage for five years that I should rebuild/replace along with new ignition, coil, etc? Has anyone had their carbs rebuilt by TRF? Would be interested in all comments and suggestions. Thanks <font color="blue"> </font>
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TR6 TR6 missing and stuttering
- Thread starter HeavyB
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vettedog72
Jedi Knight
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I would put some additive in the gasoline if you are going to allow it to sit for more than a few months. There are all kinds of fuel additives: fuel system cleaners, fuel system dryers (mostly alcohol I think), and some chemicals that prevent gasoline becoming rancid and even turning into a solid. Frankly, you are lucky the fuel lines are not plugged from sitting for 5 years.
If your problem is only when the engine warms up, I doubt that it is the carburetor. Be sure your choke is fully off when the engine is warm. The choke cable could have a problem where the wire end slips in the choke actuator on the carburetor and it is not fully off.; or, the cable may be defective. The late model TR6's have a sensor in the cooling system that allows the vacuume advance to work when the engine warms up (and not to work when the engine is cool). I would check this system out for loose vacuume lines and if that is not the problem check the timing,
I am sure you will get some good advise from the group, but in the mean time, try the above.
If your problem is only when the engine warms up, I doubt that it is the carburetor. Be sure your choke is fully off when the engine is warm. The choke cable could have a problem where the wire end slips in the choke actuator on the carburetor and it is not fully off.; or, the cable may be defective. The late model TR6's have a sensor in the cooling system that allows the vacuume advance to work when the engine warms up (and not to work when the engine is cool). I would check this system out for loose vacuume lines and if that is not the problem check the timing,
I am sure you will get some good advise from the group, but in the mean time, try the above.
AltaKnight
Jedi Knight
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Difficult to say what the problem is, a little detective work should help though.
I would start by taking a look at the spark plug ends to see if it's running the right mixture from the carbs. They should be a tan colour, if theyre sooty black then it's too rich, if they're kind of white then too lean. Check the gap while you're at it, about 25 thou is right, and make sure you have the right type of plug installed.
The electronic ignition could also be a problem, can't check much there yourself except to try a different setup (your mechanic may be able to test it though).
You should also run a compression test on the cylinders just to be sure there isn't something major wrong in there.
As Vettedog72 mentionwed loose or leaking vacuum lines can create these problems so look those over.
I would start by taking a look at the spark plug ends to see if it's running the right mixture from the carbs. They should be a tan colour, if theyre sooty black then it's too rich, if they're kind of white then too lean. Check the gap while you're at it, about 25 thou is right, and make sure you have the right type of plug installed.
The electronic ignition could also be a problem, can't check much there yourself except to try a different setup (your mechanic may be able to test it though).
You should also run a compression test on the cylinders just to be sure there isn't something major wrong in there.
As Vettedog72 mentionwed loose or leaking vacuum lines can create these problems so look those over.
Geo Hahn
Yoda
Offline
A low speed miss that comes on after the engine warms up makes me think 'ignition'... but that is on a car with points.
Could be a failing coil... that is real easy and fairly cheap to test by substituting a new coil. If you want to justify the expense, accept that everyone should carry a spare coil anyway.
I think you said you had the elctronic ignition 'adjusted' which I take to mean the timing was set... and it ran fine for awhile. You should check the timing in case the distributor has moved a bit - although I do not know what correct timing would be with whatever set-up you have.
Could be a failing coil... that is real easy and fairly cheap to test by substituting a new coil. If you want to justify the expense, accept that everyone should carry a spare coil anyway.
I think you said you had the elctronic ignition 'adjusted' which I take to mean the timing was set... and it ran fine for awhile. You should check the timing in case the distributor has moved a bit - although I do not know what correct timing would be with whatever set-up you have.
My '76 did that for a long time until I dicovered a bad intake leak in the EGR valve. Then it ran OK as long as I set the ignition well advanced from spec.
I run about 4 degrees BEFORE TDC instead of the 4 degree AFTER specified in the manual. It also likes a dwell of over 40 degrees instead of the 35 specified. I plugged the vacuum retard circuit.
Never did figure out why, but the car runs fine with these settings. When I set it back to factory spec, it still misses badly at under 2500 rpm.
Go figure. It's English.
Jim
I run about 4 degrees BEFORE TDC instead of the 4 degree AFTER specified in the manual. It also likes a dwell of over 40 degrees instead of the 35 specified. I plugged the vacuum retard circuit.
Never did figure out why, but the car runs fine with these settings. When I set it back to factory spec, it still misses badly at under 2500 rpm.
Go figure. It's English.
Jim
Offline
[ QUOTE ]
I run about 4 degrees BEFORE TDC instead of the 4 degree AFTER specified in the manual. It also likes a dwell of over 40 degrees instead of the 35 specified.
Jim
[/ QUOTE ]
Increasing the dwell from 35 to 40 degrees will retard the timing about 5 degrees, which offsets the timing advance increase.
D
I run about 4 degrees BEFORE TDC instead of the 4 degree AFTER specified in the manual. It also likes a dwell of over 40 degrees instead of the 35 specified.
Jim
[/ QUOTE ]
Increasing the dwell from 35 to 40 degrees will retard the timing about 5 degrees, which offsets the timing advance increase.
D
[ QUOTE ]
Increasing the dwell from 35 to 40 degrees will retard the timing about 5 degrees, which offsets the timing advance increase.
D
[/ QUOTE ]
I do not sidpute this, but for my education, is the dwell a measure of the period the points are open or closed? If I recall correctly the plug fires at the instant the points open, correct?
Increasing the dwell from 35 to 40 degrees will retard the timing about 5 degrees, which offsets the timing advance increase.
D
[/ QUOTE ]
I do not sidpute this, but for my education, is the dwell a measure of the period the points are open or closed? If I recall correctly the plug fires at the instant the points open, correct?
Offline
Hi Adrio,
Dwell is a measure of the time (in rotational degrees) that the points are closed. Dwelling in the closed position, not moving. To get more dwell, the point gap must be reduced. This automatically moves the rubbing block further away from the cam so that the block contacts the cam lobe later in it's revolution which retards the timing. -- Or -- More dwell = less point open time = later opening point on the cam. By the same reasoning, rubbing block wear reduces the point gap, increases the dwell, & retards the timing.
D
Dwell is a measure of the time (in rotational degrees) that the points are closed. Dwelling in the closed position, not moving. To get more dwell, the point gap must be reduced. This automatically moves the rubbing block further away from the cam so that the block contacts the cam lobe later in it's revolution which retards the timing. -- Or -- More dwell = less point open time = later opening point on the cam. By the same reasoning, rubbing block wear reduces the point gap, increases the dwell, & retards the timing.
D
[ QUOTE ]
Hi Adrio,
Dwell is a measure of the time (in rotational degrees) that the points are closed.
[/ QUOTE ]
Thank you Dave. I knew it measured either closed or open and now that I know it is closed that is measured I agree with the previous post (not that I ever disagread, just that I was not in a position to know /ubbthreads/images/graemlins/confused.gif now I am) where is the happy face with a light bulb over its head??
Hi Adrio,
Dwell is a measure of the time (in rotational degrees) that the points are closed.
[/ QUOTE ]
Thank you Dave. I knew it measured either closed or open and now that I know it is closed that is measured I agree with the previous post (not that I ever disagread, just that I was not in a position to know /ubbthreads/images/graemlins/confused.gif now I am) where is the happy face with a light bulb over its head??