[Healeys] SU Fuel pump points

[Bob Spidell]

There is no definitive answer. Sitting on the shelf, the points on a 
pump can oxidize and the pump may not work 'off-the-shelf' without a 
points cleaning (same for a car that sits too long). Note the points' 
throw-over mechanism, set up properly, is designed to 'wipe' the points 
with every cycle. Norman Nock said the pump would be removed and the 
points cleaned as part of normal dealer maintenance, at around 10K miles 
IIRC.

At one time, at least, there were aftermarket points sold--maybe before 
SU Burlen got back in the business--that came in a generic white box and 
were made in one of the Chinas; quality was as expected (i.e. 
non-existent). I had a set fail in a couple hundred miles. I discussed 
this with the late Dave DuBois, who had a post-retirement avocation of 
pump restorer, favoring various electronic mechanisms, and he confirmed 
this theory. Those points looked to me to be made of silver, instead of 
tungsten, which is a dull gray color and, I think, may be more expensive 
than silver, and the points were pitted after a few miles. Dave designed 
the original, power transistor-based mod, but switched to a 
photo-breaker mechanism later; results vary (ironically, perhaps, the 
transistor-based mod didn't send enough current through the points to 
clean them). Some have allegedly had points last for decades and tens of 
thousands of miles, and some now swear by TVS diodes (I didn't have much 
luck with them). Like any points set, the points can stick to each 
other, which is sometimes remedied by banging on the pump or its mount 
with a suitable blunt instrument (fists, hammers, etc.).

So, the answer is 'it depends.' I have had sets last several 
years--15-20K miles--and I've had various failures at points between 
with pretty much every alternative switching mechanism. As aggravating 
as the SU pumps can be, I've found engine-driven pumps to be even more 
pernicious, since filters and float bowls dry out and must be refilled 
by cranking the engine if the car has sat too long. In the case of my 
dad's '55 T-bird it's a crap shoot between the engine starting and the 
6V battery being complete drained; worst case I have to resort to 
starter fluid.

Bob

On 5/25/2020 8:11 AM, simon.lachlan at alexarevel.plus.com wrote:
>
> Basic question is: “How long, approx., should they last? (Yes, there 
> is a diode thing across them.)
>
> My car has been running OK. OKish…..I’d swapped back from Webers to 
> the three HD6s and had the car set up at the rolling road place. They 
> leaned the mixture settings somewhat, saying it would run better and 
> use less fuel. (A relative term). I noticed that it took much longer 
> to settle down after starting. Quite a lot of rude noises and much 
> play on the choke at intersections. And, when it was up to 
> temperature, I wondered whether it was quite right…was it a bit 
> sluggish or was I just used to the Webers?
>
> The other day, it hesitated and would have cut out. But, with one 
> bound I switched over pumps, and I was free! However, the pump – 
> double ended – had to come off for inspection. Both sets of points 
> were completely shot. I replaced them. Nasty, fiddly business. Now the 
> car starts much better and performs better all round. Surprisingly so….
>
> I installed that pump in 2012, +/-12,500 miles ago. So that’s +/- 
> 6,250 miles per set of points.
>
>  1. Would failing points give those symptoms? (I was/am surprised….I
>     though points either delivered 100% or failed 100%. I know that a
>     judicious thump on the bulkhead can work in the short term.)
>  2. How long would you expect SU points to last?
>
> Thanks,
>
> Simon
>
> Glorious weather here and forecast all week. Perfect Healey weather. 
> One is allowed out, but not really encouraged to go anywhere! 
> Maddening. Pubs are certainly shut. Anyhow, keep well.
>
>

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