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October 26, 2003
Yes, Martyn...agreed.
Assuming the cam is properly timed in
in accordance with previous post, I would
at this point expect an induction leak(s) of
some kind. VP3 cam or not, the engine
should be capable of reduced idle to the
point the engine will quit, though in reality
1,000rpm is a more realistic setting with
this cam and even then, it'll be pretty
lopey, even in a 1275. Not a displeasing
sound though, IMHO!! :)
Spraying carb cleaner (be
careful) in and around the induction system should tell the tale in this
respect...the idle will immediately change
if and when you hit the spot(s).
And if you haven't already done so,
you are also going to be looking for
richer needles here as well. I think the
stock SU carb set-up already has "blue"
springs so let me get out my Vizard
book here...................and..............
just as I thought...."H6" needles would
be a step up from what you've got. This
will give slightly more fuel throughout,
from "off idle". You may also have to go
to a heavier spring to prevent the carb,
air valves from reaching full open too
soon, which would actually lead to a
"weakening off" of the mixture as the
VP3 will carry the engine further up the
rev range....while the stock and even
Cooper or Metro cam would be pretty
much finished by 6-6.5K, the VP3 will be
stronger at 6.5K and will take the engine
(assuming it is capable and built well
enough to briefly get there, assuming
"correct" valve springs) right to 7K, even
with the stock carb. set-up.
BTW, should you find the carbs need to
be overhauled due to throtttle shaft leaks,
I would give some consideration to larger
1.5 SU's which would go a long way in
improving mid-range/top end breathing.
The stock manifold should be already
bored for 1.5's anyway, and can be
further "cleaned up" with a little attention
with a dremel in accordance with Vizard's
diagrams in his "Tuning BL's A-Series
Engine".
The VP3 is definitely a killer road cam...
especially with a 5 speed and 4.22...nice
combination!! :):)
Cap'n. Bob
'60 :{)
PilotRob@... 26338
Posted on October 26, 2003 07:23 PM
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