Daffy had been running very poorly at high revs recently - above about 3,500
rpm she would go through patches of hesitancy and slight spluttering and low
power at full throttle. Also, fuel consumption had dropped from the ususal
27-odd mpg to more like 18 mpg (and that is the larger UK gallon!). Something
not right, and I'm no good at carbs, so I sent her off for a full,
rolling-road tune-up.
Well, apparently the jets and needles are both badly worn, but they did the
best they could with what was there, with a recommendation to renew. What a
difference! She pulls smoothly (if not all that hard) right through the rev
range, and fuel economy is right back where it should be.
Anyway, to the point. By chance, yesterday evening I found myself on an almost
empty dual carriageway, late at night (on the way back from my Grandfathers
birthday dinner), so I thought it was a good opportunity to see just what
Daffy can do! Well, the answer is, about 95 mph in 4th, and one or two mph
less in overdrive, with the possible help of a slight incline. Not too
shabby, considering that new, the (UK-spec, twin SU, no emission control stuff
or catalyst) 1500 was supposed to do 100 mph, and she is 22 years old with
very worn carbs. Good fun, anyway (there aren't any police-men amongst the UK
listers I hope!).
I was also told that the maximum power they got on the rolling road was 40 bhp,
and he said that was what it should be for a UK Spit 1500. Now, as far as I
am aware, power output at the flywheel for the UK 1500 should be about 75 bhp
- surely I cannot be expected to lose almost 1/2 of that in the drivetrain?!
That would mean that US-spec 1300 Mk IVs, with only about 45 bhp at the
flywheel, would only have about 10 bhp to drive them forward, surely not
correct?
Oh well, I shall get new jets and needles as advised, and if I'm feeling
extravagant I may take her back and see what they get out of her with new
parts. And if I manage to post a higher top speed, I'll let you all know!
Richard and Daffy (maxed out and having fun!)
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