Upgrade from Generator to Alternator - thoughts?

[tdskip]

Hi everyone! My TR4A still has a generator (looks like it might be original) and was wondering how much of a difference upgrading to an alternator would make.

I have a spare new Lucas alternator, and I've heard my MGB friends say good things about modern GM (or similar) alternators.

I'm not planning on hanging all sorts of new electronics on the car, just modern headlights and stock gauges (no radio - who needs it with a TR exhaust!).

What do you all think?

 

[Alan_Myers]

Hi,

If you aren't planning many changes, the stock generator should be fine for moderate use, so long as you have a decent battery, wiring connections throughout the car are reasonably good and generator/voltage regulator are up to spec... and you don't go for long, cold, rainy night drives with headlights on, wipers slapping away and the heater fan running full blast!

However, you say modern headlights, and that makes me wonder, what wattage? I think most TR4/4A headlights were around 50-55w on high beam. Modern are usually 60w, unless you use an "off road" bulb, that might be 100w or more. So, the "standard" modern bulbs should be marginally okay, but any high output bulbs might start causing battery drain problems.

If you ever consider an electric radiator fan, electric fuel pump, auxiliary lighting, etc., you will likely need to consider an alternator.

I installed a Delco 7127-3 on my TR4 to support extra power users like those. The alternator itself is a rebuilt unit bought locally for only $50, but that's just the tip of the proverbial iceberg. By the time I was done, I'd also converted to a thin belt and installed a harmonic balancer.

The Delco 7127-3 is a 60-65 amp alternator, probably higher output than that Lucas (which is probably 35-45 amps). The Delco needed some minor modification on its lower front mounting lug, the original adjusting arm had to be straightened and I ended up fabricating a mount using mostly original brackets, but with a single, long bolt and a spacer with an additional small rear bracket welded on. A few washers were needed to fine tune the fit, but it's good and a few photos of the installation can be seen at the link below, by my signature, if you wish to see it.

The Delco 7127-3 is roughly the same weight at the original generator, but is shorter and a larger diamerter. Fitting in TR4 was no problem, might be though on a TR3 due to inner fender clearance. I have yet to complete the wiring, but the main feed off the alternator will at least be doubled up to accomodate all the extra juice it will need to flow. I found a connector pigtail/plug locally, very low cost. That's one nice thing about using something as common as this Delco. It's a 3-wire alternator, which means I'll be able to maintain the stock amp gauge if I wish. I prefer this over the "one-wire" alternators being offered. I did convert the car to negative ground, too.

There are other 7127s, with the wiring connectors at different locations or "clock". The "-3" indicates a 3 o'clock position, which is ideal on TR4/4A since it locates the wiring as far as possible from the exhaust manifold.

There are smaller, lighter "racing" alternators with 50-70 amp output, but I don't know if there is a model with the same mounting arrrangement as the 7127-3 (which pretty easily adapted to TR4). "Racing" alternators tend to be a whole lot more expensive.

One last thing, if you install an alternator or otherwise have reason to remove the generator... It's a really good idea to remove the bolts holding the orginal generator bracket to the block, drill them for safety wire and use some when you put them back in. The reason is the bolt holes in the block are drilled right through into the oil passeges, and you can end up with a real mess if a bolt ever vibrates loose and drops out!

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[Bob_Muzio]

Tom, I think Alan covered the subject expertly. FWIW I converted my "64 TR4 to a Delco marine alternator and my '63 E-type to a Hitachi alternator. I like the conversion as I can have wipers, halogens, CD player and the electric cooling fan on the cars without the lights diming when I turn something on. The CD player in the Jag would turn off when the electric (modern) cooling fan kicked on (even during the day). The TR, at idle, would allow the lights to dim with the generator.
There are some modern enhancements that don't change the character of the cars but make them even more enjoyable.
Bob Muzio

 

[JimK]

I converted my 71 MGB-GT to the Delco. Make sure that there is as close to zero vibration as possible, and all the alignment is good. The extra amps really make a difference with my daily driver - I live in Alaska and the weather is "variable" necessitating the use of all electrical components for long periods of time. Good luck!

 

[JFS]

I pretty much did on my TR3 what Alan did and for the same reasons except that I used a Delco one-wire alternator. I gutted the control box and used it as a junction box which made for a neat installation. This conversion along with a new wiring harness has served me well for over a decade. I run Hella headlamps, period Lucas style driving lamps, Spitty heater motor, radiator fan, electric fuel pump and nonelectric exhaust for my sound system.

 

[dklawson]

There are lower wattage "sealed-type" halogens that aren't as power hungry the replaceable bulb type. They are typically around the 55/60 Watt range and wouldn't tax the generator very much... particularly if you aren't doing a lot of night driving.

I like the look of cars with generators but I have upgraded the GT6 to a Delco alternator and have put a Motorola unit in the Mini. I've never had a lot of confidence in the generator control boxes. However, if you've got a good one (and I didn't) that and a solid generator will handle the basic car configuration you've described.