Quote:
Given the choice, I would always use a Lucas distributor as a basis for experimentation, or indeed to use unaltered as the Delco one fitted to Spitfires and GT6s are particularly nasty, cheap, fast wearing things which I bin at the earliest opportunity.
I was surprised to see an AC-Delco ignition distributor, intended for use with a Triumph Spitfire. I had previously associated AC-Delco products with General Motors – Vauxhall! I confess that for one reason or another, I wasn’t greatly impressed by the look of the illustrated Delco distributors with Powerspark electronic ignition, but I was unaware that they had a reputation for being of poor quality.
Quote:
In theory you are perfectly correct, a 6 cylinder distributor runs at exactly the same half engine speed whether it is in a 6 cylinder car or a 4. So it is reasonable to assume that you can make a 25D6 distributor with tacho drive (from say a Vitesse 2 ltr) into a 25D4, merely by swapping in the relevant 4 cylinder points operating cam (and dizzy cap of course) from your old Toledo distributor (or one from a Herald, Mini, Moggy Minor, the list is endless).
That sounds interesting! Unless the Triumph Vitesse & GT6 engines, have the same centrifugal and vacuum advance curves as my Toledo engine, I would imagine one would also need to swop over the ignition-advance mechanisms as well, including the centrifugal bob-weights & springs and the vacuum canister.
I have previously dismantled a Bosch ignition distributor (two sets of contact-breaker-points, for the ignition system and Bosch D-Jetronic fuel-injection system), originating from a 1971 VW 411LE, but I have yet to try this with a Lucas distributor.
The original Lucas ignition distributor on the engine of my Triumph Toledo 1300 (first registered in mid-November 1974 – since driven circa 101,000 miles), is marked Y in a circle, followed by
41449 B 45D4 »---» 3674, so I presume it is a Lucas type
45D4 distributor, that I suspect was also used on the Triumph Dolomite 13/1500. I don’t know what subtle ways this differs from a
25D4 distributor, but judging from the illustrations in the workshop manual, two obvious differences are the
45D4’s lack of an ignition-timing, knurled fine-adjustment screw and the construction of the 45D4’s contact-breaker points, which also features a vertical two-pronged fork to hold a felt grease-pad to lubricate the four-lobed cam.
Quote:
And so long as you connect it to a matching Tachometer, it will work fine and read as true as any magnetic induction guage. I don't, unfortunately, have any spare 6 cylinder Lucas distributors with tacho drive, but I do have a fair selection of cable drive rev counters from various Spitfires, Vitesses and GT6s.
If you like, I could take some pics and see if any of them take your fancy, I may even have matching speedos for some of them!
I have seen a few cable-driven engine-tachometers, which appear to be a good match with the style of my Toledo speedometer; including a few with either one or two integral warning lights.
Smiths Rev Counter RN2318 /00 & Matching Smiths 140mph Speedometer SN 6203 /38A
http://www.ebay.co.uk/itm/Smiths-Rev-Co ... Swol5Y2pP1
TRIUMPH GT6 GT6+ Tachometer Smiths 7000RPM 1970-1973 RN2318/00
http://www.ebay.co.uk/itm/TRIUMPH-GT6-G ... SwhlZYtkqF
Triumph GT6 MKII, MKIII Tachometer , Smiths RN2318/00 , Triumph # 215044
http://www.ebay.co.uk/itm/Triumph-GT6-M ... Sw0JpV5L4e
SMITHS REV COUNTER TACHOMETER TRIUMPH KIT CAR
http://www.ebay.co.uk/itm/SMITHS-REV-CO ... Sw32lYusYN
TRIUMPH GT6 TACHOMETER BEAUTIFIL FACE SHINEY CHROME
http://www.ebay.co.uk/itm/112278215343?ul_noapp=true
There is no doubt that pairing such an engine-tachometer with an exactly matching speedometer, originating from the same car, has much to commend it, but it’s debatable whether the calibration of a Triumph GT6 speedometer (with three integral warning lights), would be appropriate for a Triumph Toledo’s gearing; even one like mine whose effective overall gearing with 185/65 R15 tyres, will be almost identical to that of a factory-standard Triumph Dolomite 1500.
My Triumph Toledo 1300’s Smith’s speedometer, is capable of showing a maximum scale-reading of
100 mph (large-numeral outer scale) or
160 km/h (small-numeral inner scale).
British specification, 1974 Triumph Toledo 1300's Smith's speedometer
Intriguingly, Page 7 of my English-language, Triumph Toledo 1300 owners’ handbook, illustrates a speedometer of similar appearance to mine, whose
large-numeral outer scale is calibrated in
km/h (i.e. 0~160 km/h) and
small-numeral inner scale is calibrated in
mph (i.e. 0~100 mph). How weird is that!?! That said, such a speedometer was used on the New Zealand specification, 1974 Triumph Toledo 1500, as I recently discovered.
New Zealand specification, 1974 Triumph Toledo 1500's Smith's speedometer
Given that the statutory
maximum speed limits in most European countries are 70 mph, 110 km/h (i.e. 68¾ mph) or 130 km/h (i.e. 81¼ mph), even the Toledo speedometer is over-rated; especially for a Triumph Toledo 1300, whose theoretical maximum speed, is no more than 85 mph. The Triumph GT6’s 140 mph dial face, is even less appropriate to a Triumph Toledo 1300; 140 mph being exactly twice the British statutory
maximum speed limit of 70 mph, so only half of the speedometer’s scale would ever be used!
The cable-driven, engine-tachometers’ pair of integral warning lights, seem to be one of green colour for direction-indicators and the other of red colour for a rear-window demister. Given that I intend to substitute a late-model Dolomite square-knobbed, heated rear-window switch, the red warning light is quite apt. The green direction-indicator warning light, could probably be used for the statutory, trailer’s direction-indicator warning light.
I also wonder whether it would be practical (or even possible?), to incorporate some additional warning lights, into the housings & dial-faces of an engine-tachometer (cable-driven or electronic) and speedometer. Firstly there would need to be sufficient space inside the housings, for the bulb holders cum black “light-tubes”. The next challenge would be to dimple the dial-faces in the appropriate shape and location, without otherwise distorting the dial-face or compromising the paint finish!?!
I am mindful that the speedometers of the BMC Austin-Morris Mini and the Morris Minor, both had speedometers with several integral warning lights, plus an integral fuel gauge. Sadly, they appear to be of five inches diameter, which is too large for my transplanted Dolomite HL instrument panel. Four-inch speedometers for the late-model, air-cooled, North American specification VW Type 1 Beetle, had seven integral warning lights and an integral fuel gauge.
Vintage Morris Minor classic car smiths speedo speedometer 95mph SN4423/00
http://www.ebay.co.uk/itm/Vintage-morri ... 2348976ab5
80060000113h4444 - Mini Cooper speedometer (four warning lights and integral fuel gauge)
http://new.minimania.com/images_temp/80 ... 3h4444.jpg
_________________
Regards.
Nigel A. Skeet
Independent tutor of mathematics, physics, technology & engineering, for secondary, tertiary, further & higher education.
https://www.linkedin.com/profile/view?id=308177758
Upgraded 1974 Triumph Toledo 1300 (Toledo / Dolomite HL / Sprint hybrid)
Onetime member + magazine editor & technical editor of Volkswagen Type 2 Owners' Club