While waiting for FedEx to deliver parts needed for inside the doors I'm doing small projects. I've had the top frame ready to go on for months and just hadn't installed it. Now I have. Unfortunately the top that was ordered 3 months ago and was charged for still hasn't materialized.
I also planned out what's needed on the dash for custom wiring. There are two control switches for the heated seats, a Megasquirt logging button and indicator light, and a check engine light. Those went on the radio blanking plate.
I also have a much bigger solenoid valve for controlling fast idle. This one shouldn't add as much restriction.
Sometimes the little stuff can be frustrating. I spent 3 hours today removing the too small fast idle solenoid and putting in the bigger one. The new one flows much better, but I also decided to upsize the hoses and fittings. The valve is dimensionally big enough to barely fit in the space used before, but it's in.
The idle is now around 1200 RPM cold, but I still need to add fuel to get a richer AFR. I'm also adjusting cold timing advance to even up the idle as warmup progresses.
Next up is finishing the wiring under the dash. As it stands now, this is just the Megasquirt indicators/logging button and the heated seats. So far the ammeter has been handling the current load, but on the high setting both heated seats together draw 5 amps. So I checked the power draw of every component. Here's my budget.
Car running no lights - 23 amps (This includes brake lights, overdrive, purge valve, and the cooling fan running steady)
Lights - 11.7 amps
Blower Motor - 3.4 amps
Wipers - 10.5 amps
Turn Signals - 3.8 amps
Horn - 8.4 amps
With just the lights on, I'm potentially pulling 35 amps. That's the original alternator capacity for 1972. Later cars had a 45 amp alternator, but used a voltmeter instead of a 30 amp ammeter.
So if it's a rainy night, I'm in trouble even without the heated seats.
The 30 amp ammeter is the biggest issue. The wire connecting it to the alternator and battery looks like 8 gauge but it's older and may only be 10 gauge. It should be good for the original alternator, but the new one is rated at 55 amps. That's a little marginal for a roughly 6' length. So it looks like to be safe I need to replace the wire running from the alternator to the ammeter and the ammeter to the battery/starter. I also need a 60 amp ammeter. Doing this should allow me to handle the full 55 amps from the alternator and stay just below that with the heated seats on. Transient devices such as the horn could push it over.
From Googling, some have put a shunt in parallel with the ammeter to divide the current. Someone suggested about 3.5" of 16 gauge wire, but this seems variable (e.g., who made the wire, how good are the connections). We are talking micro-ohms of resistance here. Another suggestion was to run a secondary wire from the alternator to the battery, but this interferes with the function of the ammeter to indicate charging status. I've done this for now to ensure the original wires and ammeter do not melt.
Or I could simply avoid driving on a cold, rainy night.
In reply to JoeTR6 :
Why not change it to a volt meter and eliminate all of the high load wire behind the instruments? Then you are set for a later upgrade to a 100 amp alternator if needed.
I’m inclined to agree on the change from the ammeter to the voltmeter. The ammeter and it’s wiring is one of the known failure points electrically on the ‘72 and earlier cars.
My car is a 73, so it has a voltmeter already, but I did upgrade to a Delco 10si alt to get more charging power.
RevingtonTR has a solution to my problem, but it isn't cheap (about $265).
New 60 Amp Ammeter
It may come down to this, but first I'm going to experiment with putting a shunt on my spare gauge. I'll go ahead and upgrade the harness wire to 8 gauge.
Revington also makes a new digital tach and speedo, but they are pretty expensive. The speedo can be calibrated for different gear ratios, so may make more sense than sending off the old one for a rebuild.
TurnerX19 said:
In reply to JoeTR6 :
Why not change it to a volt meter and eliminate all of the high load wire behind the instruments? Then you are set for a later upgrade to a 100 amp alternator if needed.
I'm considering it. The thought of a shunt made from 16 gauge wire carrying 25 amps worries me. I read on the RevingtonTR site that the later ammeter is rated for 50 amps, so maybe a heavier shunt to bypass just 10 amps would work. Maybe. Until the car catches fire. The thing I don't like about this "fix" is that if the ammeter fails, all of the current goes through the shunt and it won't handle it well.
I did finish the wiring under the dash and will leave out the heated seat fuse for now.
I've been putting off making a decision about the alternator wiring by working on the doors. First up was regluing the door top crash pads which I managed to glue 1/4" too far forward. They came off not once, but twice. Something about my technique wasn't working, but the third time was the charm. Using contact cement makes this task a PITA, but it holds well.
A few weeks ago I gave up staring at the old window tracks that were laying on my work bench and ordered new ones from TRF. These worked great 25 years ago, but now they were only 75% viable. The rear driver door track just doesn't fit without widening the holes in the door and leaving some hole exposed. Comparing to an original one, the upper mounts are 1/4" too low and too close to the track.
Another issue are the nylon blocks that the window rubs on. They are instead some really soft Teflon-like material. The other three channels use the original nylon, so this must be from a newer batch that didn't turn out quite right. Worst case, I can reuse the original for now. The passenger door can be finished tomorrow after the window regulator crank gear finishes a derusting soak.
The old Triumph ammeter wiring on my old TR4A always gave me pause and when I added an alternator (replacing the generator), the wiring was definitely not up to the job. I hated how the stock wiring runs all the charging amps thru that gauge on the dash. I would also second the motion to just convert to a voltmeter. On the car as I am building it now, I ended up ordering a custom Advance Autowire kit for a V8 TR6, as this gives me all the circuits I need for the V8 and is set up for a GM alternator.
The door glass is in. There was some misalignment on the passenger side with the windshield frame that was fixed by loosening up the windshield mounts. At first the glass wasn't overlapping the fuzzy door seals enough, but the upper stops were set at the lowest setting. There's some tweaking left to do, and the top "seals" need to go in to set the window height.
This is one of those jobs where having skinny arms is an advantage.
I will be rebuilding the doors on the TR4A and not looking forward to it. Have new TRF window tracks and new windows, so should be fun. I am sure there is lots of fiddling to do. Keep up the good work, you are getting closer each day!
I can't ignore such sage advice concerning the ammeter. Good thing I kept a voltmeter from my '73 TR6 parts stash. It even works and cleaned up nice.
So for the alternator wiring, I'm thinking 6 gauge wire running under the hood along the firewall. Keep the fire under the bonnet where it belongs, right? I already have a later battery cable with extra lucar connectors, so wiring that should be trivial. The voltmeter just connects to the white circuit (switched power) and ground.
I got tired of waiting on Robbins to manufacture a soft top, so I canceled that order and just bought one from Moss that had one in stock. It's just as well. The original order was for a canvas top with the reflective stripes. After looking at a few photos, I think it looks cleaner without the stripes. Hopefully I'll have a top to install within a week. I'm also waiting on 6 gauge wire, a replacement window channel, and some small hardware to arrive.
So in the mean time, I decided to tackle an issue with the coolant. It's been getting steadily darker and more reddish, so suspected that rust from the block has been getting stirred up. Last night I drained the coolant and let it sit overnight with just water. There's no froth, just some silty sediment. This morning I drained that and began flushing the system with water. This probably didn't clear the heater core, so I drove about 6 miles and the overflow bottle was once again murky. It got drained again, and while dry I installed a Prestone backflush tee in the heater hose and a 180 F thermostat (I had been running a 160 F thermostat). Next week it will go to a trusted local mechanic to be flushed with the engine running.
Nice progress, Joe.
Is there any sort of coolant-system detergent that you can run thru it? Or just flush and fill until it's coming out clean?
I may be confused, but are you running 6 gauge to the voltmeter?
matthewmcl (Forum Supporter) said:
I may be confused, but are you running 6 gauge to the voltmeter?
No, 6 gauge from the alternator output directly to the positive battery cable. The voltmeter will just be connected to the original switched power circuit. Sorry, that was a little unclear.
TVR Scott said:
Nice progress, Joe.
Is there any sort of coolant-system detergent that you can run thru it? Or just flush and fill until it's coming out clean?
I was considering putting in some Prestone flush or something like it. I've only used that once on a '84 Honda Prelude and it didn't seem to hurt anything. Part of me wants to fill the system with something like Evaporust to chemically convert the rust, but that could have some bad consequences. Need to do more research.
JoeTR6 said:
Anyone tried this stuff?
Evaporust Thermocure
Looks like the right idea to me.
In reply to TVR Scott :
It's on it's way. The sediment is less now, but it would take several days of flushing to get it mostly clear. This stuff should put the rust into solution and get it out.
The Evaporust Thermocure is doing it's thing. I'm going to drive the car occasionally for three days and see what comes out. Then it gets a backflush with the hose.
Today was trunk day. Triumph used a soft fiber board to line the trunk. It's something, and looks better than without. But the carpet is wool.
The original factory trunk light was junk. That cheapo reproduction is absolute garbage. I had to do this just to keep the bulb from flying out.
I'm guessing I'll replace the light fixture before the bulb.
I also mostly completed the ammeter to voltmeter conversion. The 6 gauge wire was run under the dash along the main wiring harness with wiring loom for protection. The car would run if I connected the other wire that draws power from the ammeter connection. This goes to the ignition switch and powers the switched circuit. I'll probably just hook this up to the now unused brown wire coming from the starter. Edit: Done, and it runs.
The voltmeter looks different than the other gauges, but I can live with that for a more reliable setup. I've considered flipping it over, but redoing the lettering just isn't worth it.
JoeTR6
Dork
8/25/21 10:17 p.m.
The voltmeter is wired and works great.
Since the Thermocure stuff is stewing, I drove down into Colorado Springs this afternoon to get it flowing. Unfortunately, I didn't check the outside temperature first. It was near 90 F, so the TR6 (and myself) ran a little hot. Maybe the 160 F thermostat *is* what I should be using. With the elevated temperature, it was running way rich for some reason, especially at idle. Hopefully tomorrow I can download the logs from the SD card and see what was going on.
In other news, the parts order from Moss arrived. After draining and flushing the cooling system, the top can finally be installed.
The cooling system is clean enough. I drained the Thermocure yesterday and did four rounds of fill and drain. The radiator was clear, but what was coming out of the block was still slightly tinted. Since the system was completely flushed of coolant and the Thermocure is non-toxic and biodegradable, I hooked a hose up to the back-flush port and ran it for a few minutes. The system was refilled with Prestone and Water Wetter and there is just a small amount of black sediment (converted rust) in the overflow after a 10 mile drive.
So on to the soft top.
What's worse than a 50 year old Lucas switch? It turns out the brand new Chinese made reproduction switch. At least the Lucas switch still works.
The story is that I wanted to put something in the hole left by the choke cable. So I figured I'd stick a two position heater switch in there and pop a knob on it. It might come in handy for controlling some function such as an interior LED light strip or an ejector seat. The switch I put on the last order from Moss only cost $20, and it does hold the knob, but something is wonky inside. I'll eventually pull it apart and see if it can be fixed, but it's really too cheap to return. And the hole is filled.
!
