Quote from Colin on 1st September 2010, 9:40 pm

This may not be that much interest to 1800 owners with engine driven cooling fans but it may well be of interest to those with an electric fan(s)/ cooling issues.

My V8 was running the standard original fitment 45 amp alternator and whilst generally adequate in most driving situations It did have a problem with the fans running slowly whilst on tickover/in traffic. Although the engine was far from overheating I was concerned with the amount of time that the fans remained on for (almost permanent until I got some speed up) and the resultant wear on the fan motors/the alternator having to work harder.

With this in mind I firstly looked at increasing the output of the standard AC Delco unit but found it wasn't possible to increase its output so i looked at alternatives and found that I could adapt a generic Ford alternator to suit the V8 and by changing the regulator increase the ampage to a massive 70amps. I don't want the extra amps for lots of lights etc but as you know an alternator is a bit like engine bhp so the maximum 70 amps isn't available until around 2,500 rpm but what it does do is give you a lot more lower down the rev range verses the original unit-50% infact so at 750 rpm I have the 35 amps that the original produced (when new) at 2,500. Well that's the theory anyway.

Before swapping them today I checked out the speed of the fans with the old alternator before replacing it with the new one and repeated the check

[b]This first pic shows the original AC Delco 45 Amp unit[/b]

[img]https://www.mgbjubilee.com/images/articles/V8_Alternator1.JPG[/img]

[b]The engine speed for all of these tests was approx 600rpm[/b]

[img]https://www.mgbjubilee.com/images/articles/V8_Alternatot2.JPG[/img]

[b]Here you can see clearly that the fan speed was 2402 rpm[/b]

[img]https://www.mgbjubilee.com/images/articles/V8_Alternator3..JPG[/img]

[b]Here you can see the new adapted unit-which infact has more clearance to the rocker cover than the Delco unit[/b]

[img]https://www.mgbjubilee.com/images/articles/V8_Alternator4.JPG[/img]

[b]And here is the result 2,600 rpm which is a healthy 200 rpm more-this actually raised to 2,800 when I raised the idle to the correct 750rpm[/b]

[img]https://www.mgbjubilee.com/images/articles/V8_Alternator5.JPG[/img]

I am very happy with the 17% increase and in real terms it has meant that the fans spin for less time and actually (on a simulated town test in the garage with the door open) the temperature actually reduced enough for the fans to shut down for over a minute between cycles.

I have looked on eBay and can't find anyone else offering a similar item so am thinking of selling them on there-more money that the Mrs. won't find towards new projects;).

[center][u]If any of you out there who have purchased the 65 amp 1800 unit on the recent GB have a meter to measure the fan's speed it would be interesting to see how much of an improvement you get[/u][/center]