Chip noticed some squeaking in the front end of the project TR6 and decided to replace some bushings in the front end with Richard Good Nylatron bushings.

Above are the offending squeakers.

This photo shows the new bushings install on the lower control arm.  Chip also inverted the control arm to lower the car a bit.  This car will also get Spax shocks on the front and new springs.  After all of that, we can get it off the rack and note any improvement.

Thought I’d introduce another tool Chip is using to tune the TR6.  It’s a software program that plots the Air/Fuel mixture ratio using a sensor mounted in the exhaust.  This little tool helps to see how close we are getting to complete combustion.  If anyone is wondering, we are currently a bit rich, so we can lean it out a bit.  Our formerly weak ignition (see the previous article discussing Distributor Phasing) needed more fuel, whereas the properly functioning ignition requires less.  We like efficiency.

Ignition what?  Read on, I’ll explain.

Adjustments continue towards the goal of maximizing the efficiency and response of the stock tuning on the ’76 TR6.  Chip wants to get the car running as well as possible to serve as an accurate baseline prior to making any improvements.  The latest adjustments were motivated by a miss that developed after a long highway run.

Chip went to a meeting in the Fredericksburg, VA area that facilitated running the non-overdrive, 4-speed TR6 an extended period of time on Interstate 95 at moderately high revs.  The car ran well on the trip up.  On the return trip home, an intermittent miss developed, leading Chip on a search for the cause.

It turns out that while the timing on the car was set correctly (the plug fired when the piston was at 10 degrees Before Top Dead Center with the vacuum retard disconnected), the spark was weak because the rotor was not lined up where it should be at firing time (it was out of phase).  Take a look at the picture below for an explanation and please forgive the crude labels.

In the picture above, the distributor cap is off.  The black dot is the location of the #1 cylinder contact location when the cap is on, so that’s where the rotor should be at firing time, just like it is in the picture.  The distributor in the picture is phased correctly (now).  Prior to the fix, the rotor was about 20 degrees past it’s intended firing position, which made an awfully long arc for the signal to jump.

In order for the distributor to fire correctly, the rotor should line up with the cylinder contact at the same time the optical sensor (see picture) lines up with the break in the wheel.  There are six breaks (one for each cylinder).  The optical sensor is facing away from us and towards the center of the distributor.

Above is a picture of the distributor from the other side (optical sensor is now at the 12 o’clock position) without the rotor.  It’s a tad out of focus, but it helps to see how the breaks line up with the optical sensor.  Now, let’s go back to the other side and look at one last thing.

The picture above shows the distributor with the cap removed.  We had a different rotor on at this time, so that’s why it’s not the blue one.  The yellow arrows in this photo point to the adjustment available.  Previously, the rotor was rotated a good 20 degrees counterclockwise (yellow arrow “Prior Position”) from where it is now, which resulted in it being a good ways past the dot marking the number one cylinder contact.  Since everything didn’t line up like it is supposed to, the spark was weak.

Weak spark or not, the car ran fine for a while, a testament to the strength of the ignition.  Eventually, however, running at over 3000 r.p.m.s for an extended time caused one of the spark plugs to go bad, which caused the miss Chip was hearing.

Credit for help in the diagnosis goes to Jeff Schlemmer of Advanced Distributors.  Chip has sent numerous distributors to Jeff and has been very pleased.  Jeff commented that he has seen phasing effects increase in prominence with the advent of electronic ignition retrofits to older cars. Jeff is a wealth of knowledge and well worth a call if you need a distributor resource.

So here’s the bottom line:  when all of the ignition components weren’t lining up correctly, it caused problems with the ignition (bad plug) that led to a miss.  Once Chip corrected that, the car runs like a top… which is what we’re after. Now that the car is running well, we can experiment with the effects of advancing the timing to 12 or 14 degrees BTDC.  We’ll keep you updated.

Chip ran across a 1976 TR6 that had been sitting for a number of years.  I think 7 is the number, if I remember correctly.  The clear coat is peeling off, making the car look neglected.  Chip saw some things he liked about it, however, such as the Panasport wheels and the fact that, other than sitting, it looked to be pretty functional.  This would be a great moment to include a shot of the overall car if I had one, which, inexplicably, I don’t.  I’ll put it on the list. (Click on any of the photos below to enlarge them).

Here’s a shot of the front of our beauty queen.  Somewhere along the way, someone installed an aluminum gas tank, which helps much from a corrosion standpoint.  Chip removed the tank from the car, cleaned it, installed a new fuel line, cleaned the carbs, and  it started after all those years of sitting.

Above is the view during the gas tank cleaning.  The tank was out of the car at this point and is pictured below.

Future plans for this car call for some cylinder head work, a slightly more aggressive cam, and fuel injection.  Stay tuned for further updates.