Hi List,
I finally got my Sprite back on the rolling road. Since my last session I
have fitted a 6.75" maniflow inlet manifold, shallower air filter to match,
and nology leads. Also I had the inlet manifold coated with a special thermal
barrier coating which looks a lot like silver paint.
The run revealed several things:
1. The misfire that I though had gone away is in fact still there.
2. The shallower air filter will require the rams to be shortened.
3. Because of the problems and 1 & 2 the session didn't prove how useful the
changes were.
Still, the session was good value for money - £58 for about an hour and a half
and did reveal some positive things:
A. Although it was not possible to say if the thermal barrier produced a gain
in power because of the problems it definitely eliminated all the heat soak
problems and on that basis was worth every penny. For instance, in heavy
traffic it still ran as smooth as a peach. On the dyno after a lot of full
power runs it started first time, every time which is a first for a dyno
session for me.
B. The misfire is peculiar because it comes in before 6000rpm and is gone by
7,000 rpm. It almost certainly the ignition module for the electronic
distributor - this type of module is only available as part of a package with
a performance coil so in due course I will be selling my very new Lucas
(ballasted) Sports coil (bought to cure the misfire).
C. The engine produced really strong power at 5,600 rpm then dropped more
than 10bhp by 6,000 rpm and then went back up to the 5,600rpm figure at
6,950rpm. This means that once I sort out the misfire I will have the kind of
power I am looking for - possibly 3bhp more than its all time previous best.
D. The power drop coincides with just over 110mph in 5th gear and explains
why it struggle to build speed beyond this point - with everything sorted
120mph (this is a road car) should be possible.
E. K&N are right about the gap required between the filter case and the rams
and even 2-3mm will make a difference. I will be getting the rams re-machined
to get the required reduction in height.
Daniel1312
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