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Revisiting alternator problem


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I've sorted out my electronic ignition problem, and now back to alternator. The ignition light will go out, but only if I rev to about 3000 rpm. But there's another problem: the rear of the alternator prevents access to number 1 spark plug. I've checked that I have the correct fan belt, so it will not tilt any further away from the plug and lead. The alternator is a NAPA NAL1270. Speaking to a distributor (no pun intended), the correct NAPA alternator for a 1500 spitfire is apparently NAL1635 - but I cannot find any reference to that one, but anyway, it looks like this one isn't right. Information on NAPA alternators seems a bit thin on the ground. So, firstly is it standard on the 1500 spit that the alternator must be removed or the fan belt removed to allow it to tilt away, to get to number one plug - i.e. an original lucas will do the same thing, and secondly, if the alternator is wrong does it need more revs to "wake up" and extinguish the ignition light. As usual, any help from the grown-ups would be appreciated.

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I have an uprated Lucas type alternator similar to the original and yes, to remove No.1 plug I have to loosen the top adjustment arm, remove the belt and then rotate the alternator out of the way.  The fan belt was bought as the correct item for a 1500. 

The ignition light goes out as soon as the engine starts at around 1000rpm

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cut in speeds is all down to pulley sizes  and the wattage of the warning lamp 

if someone has fitted a led warning lamp expect chaos 

ive no experience of napa alts. 

the load on the warning lamp has a big effect , (not so much on more modern units) but using a 2,2 watt rather than a 1.2watt will cut in earlier 

Pete

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So, if the alternator is obstructing no.1 plug, presumably fitting a longer fan belt would allow it to rotate further, out of the way. I wonder if there exists somewhere a database of fan belts, 10 mm X ...well, more than 1088 mm?? Same thing for the alternator pulley, I suppose. I need to try a (?)bigger pulley. Are they universal fit but different diameter? Are pulley belt widths all the same?  So many questions, so little time. What's the answer to the question of the universe ---- 42, of course.

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38 minutes ago, Doctor slow said:

So, if the alternator is obstructing no.1 plug, presumably fitting a longer fan belt would allow it to rotate further, out of the way. I wonder if there exists somewhere a database of fan belts, 10 mm X ...well, more than 1088 mm?? Same thing for the alternator pulley, I suppose. I need to try a (?)bigger pulley. Are they universal fit but different diameter? Are pulley belt widths all the same?  So many questions, so little time. What's the answer to the question of the universe ---- 42, of course.

Just a quick search on fleabay came up with this https://www.ebay.co.uk/itm/254672261461?hash=item3b4ba65155:g:ih8AAOSw2GdfJHf4  Just keep putting various size's in and they will come up. :)  I just put in 1092 x 10 fanbelt. they are all cheap enough.

Tony.

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43 minutes ago, Steve P said:

I have a Red 10mm Led ignition light

what has that got to do with a speedo  and tacho change   they are not related  to bulb type  are they ???

58 minutes ago, Doctor slow said:

need to try a (?)bigger pulley

No that will reduce the alternator revolutions and make cut in speed worse 

and yes the pulley width has to match the belt width you use    there are different width and different diameters  out there

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2 hours ago, Steve P said:

I have a Red 10mm Led ignition light due to changing to an electronic speedo and Tacho,that only goes out at about 3k rpm when started.

Steve

Unless your LED has a parallel resistor for energising the alternator your cut in speed will be high.

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27 minutes ago, SpitFire6 said:

Unless your LED has a parallel resistor for energising the alternator your cut in speed will be high.

yes this has been covered before somewhere and I think the conclusion was you can change all bulbs for LED except ignition warning light...

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10 minutes ago, johny said:

yes this has been covered before somewhere and I think the conclusion was you can change all bulbs for LED except ignition warning light...

Correct. You need to add extra components to allow to function as OEM Ignition bulb.

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OK, I'll live with revving to about 3000 rpm to extinguish ignition light.....for now. Decided to get a 10X1200 fan belt to allow some rotation of alternator. this gives me enough room to get to plug 1 without having to move alternator. Since others have also seen this problem, was this a design thing..........." I know, let's use some old fan belt, it's too short, but we've got lots of them, you can't get to plug no. 1, but we'll let the customer deal with that ...that'll do" . 🤣🤣🤣

Thanks for all the help.

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I concluded that the problem was caused by Triumph just fitting an alternator in place of the earlier dynamo while keeping everything else the same as they already had the bits in stock.

I am using multi-electrode spark plugs with a claimed life of 25000 miles and do not need to remove No.1 plug very often so just live with the design issue.

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Are you  using one of those 'bendy' plug spanners with a universal joint right on the end of the plug socket ? Mine was bought for a motorcycle with awkward plugs. Tight but doable on my standard 1500 alternator setup without having to move anything.

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Trying hard to think of which car it was?. But one vehicle some years back had a similar issue. In the end I used a cut down tubular spanner with a (big) nut welded to the top, and used a ring spanner to get it started, once started it would come out just using the fingers?. "Thing about some cars, you have to think laterally.

Pete

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Without being immodest, lateral thinking is one of the very few things i'm not totally incompetent at, but it seemed to me that (laterally😁), a slightly longer fan belt was the easiest answer, especially since the old one was pretty ...well, old anyway. Hope i'm not wrong, but a QH 10X1200 fan belt was only 6.99, and I can't see that anything else will be damaged😬😬

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1 hour ago, Doctor slow said:

Without being immodest, lateral thinking is one of the very few things i'm not totally incompetent at, but it seemed to me that (laterally😁), a slightly longer fan belt was the easiest answer, especially since the old one was pretty ...well, old anyway. Hope i'm not wrong, but a QH 10X1200 fan belt was only 6.99, and I can't see that anything else will be damaged😬😬

Will the adjuster be long enough? Guess there is one way to find out!

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Yes, i'm pretty sure there's enough adjustment left - the 1200 is only 1.12 cm longer,  and i've tested it as much as I can without the new belt. The alternator was almost at the proximal end of the adjuster anyway and it was quite difficult to remove the old belt. Maybe Pete Lewis was right, and the alternator pulley is too big, but measuring it, it seemed right....... but anyway time will tell. It's exciting, isn't it -  bet you're all on tenterhooks.  🤣 (you may have noticed I've just found these things, whatever they're called).

I have one of those spring loaded plug spanners, but it was still too big. A tube spanner just about did the trick, but it was too short. Modifying that was more fiddly than getting a longer belt, but as I said, time will tell. Thanks again for all the help from the grown-ups.

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  • 3 weeks later...

For anyone following this project and still not bored, you may be interested to hear that I managed to get a fan belt 10 X 1110 mm, which fits well and allows removal and replacement of no. 1 spark plug.

!0 X 1120 was too long, and anyway very difficult to get hold of. (preposition is a bad word to end a sentence with). May be helpful to anyone else who wants to get at no. 1 plug without moving alternator or use of "special tool". Of course I may be years behind everybody else ....... wouldn't be the first time.

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