Randall, two questions:
If you figure out how to run your fan on a ignition off, five minute delay, pls. Let us know!
Regarding LED headlights: was there any modifications involved( new housing etc.). Also what brand are you using?
Sorry for hijacking the thread here, but hopefully not too much of a digression.
I enjoy experimenting with simple electronics, so my plan is to use a small microcontroller to implement pulse-width modulation for the fan (which I believe will reduce overall power consumption) as well as the 5 minute delay. Haven't decided which one yet, but there are many tiny micros around that would work fine for such a simple task. For example, the PICAXE-08M2 is attractive because it's cheap ($3 each for the bare chip, $30 for a development system) and comes in a package with old fashioned pins (much easier for me to work with than modern surface mount stuff).
https://www.robotshop.com/en/picaxe-08m-starter-pack-usb.html
Also here's a brief article singing the praises of PWM fan control
https://www.electronicmotionsystems.com/BPS_03-10_EMS_web.pdf
There may be off-the-shelf controllers that do all this, for example I just found the PWM85A which has a 1 minute delay
https://www.hollisterroad.com/proddetail.asp?prod=PWM85A
But I prefer to roll my own.
The headlights were totally plug-n-play, the only modification to the car was to re-aim the headlights after installation. I did buy new Hella H4 conversions as I wasn't all that happy with the Bosch units I had been running and the Hellas were on sale
https://www.busdepot.com/0301600118
The LEDs are H4 replacements that I found on eBay
https://www.ebay.com/itm/New-60W-60...006-HB2-HB3-/251680369697?hash=item3a9951ac21
They fit directly into the Hella conversions, except I had to bend the mounting spring slightly to get it around the heat sink. The little power supply lays nicely between the side of the lamp and the bucket, although it did take a little maneuvering to get it there. There are a few more photos at
https://s258.photobucket.com/user/TR3driver/library/Misc parts/LED H4 replacements
(I really should remember to clean the bench up a bit before taking photos, please ignore the mess. Also, the schematic visible underneath has nothing to do with headlights, it was for some LED turn signal/marker lights that I was working on for the front. I didn't care for the result, so I need to rethink that one.)
PS, forgot to mention before, I deleted the crank hole many years ago and the radiator that came to me in my current TR3 didn't have one either. According to my radiator guy, having the hole reduces cooling capacity by about 10%, because the tubes are cut and blocked above and below the hole. With the crank hole deleted and a stock fan, I was only having trouble with the temperature creeping up during long traffic jams in hot weather. Coming home from TRfest 99 was when I decided to abandon the mechanical fan (again), but the traffic on the 101 was it's usual "parking lot" mess and it never actually boiled over even though it took us over an hour to go 20 miles and the air temps were close to 80F. I just got tired of worrying about it!