The first point to make is that these guys know their stuff! Go and talk to
them about what you want out of the exercise and they'll likely give you
excellent advice.
This doesn't stop me from offering my opinion though! :-)
While you can customise the advance curve in conjunction with a dyno
it is a two step process with the dyno being step 1. They use a dizzy
without any advance mechanism and adjust the timing at each point in
the RPM range. You then take this RPM-advance table to an ignition
specialist who adjusts your mechanical advance dizzy (with different
weights and springs) to get as close as possible to that "optimum" curve.
When I had a "from scratch" setup, the dyno guys asked me about the
state of tune (race) then they set the max total advance to 38deg BTDC,
did complete jetting setup, then did fine tune on ignition and double
checked jetting. Jetting didn't require any changes the 2nd time around.
They knew about A series motors so they were *very* close at the first
attempt but you might not be so lucky on that front.
You really want to have the filter/carb/inlet/manifold/silencer on the car
ready to optimise the timeing & jetting. If you want to try out add-on
inlet stuff such as different filter housings then this can be done after the
first pass at timing and jetting, followed up by the fine tune on jetting
after the ancilliaries have been selected.
Unless you are preperaed to spend more $$, trying out different manifolds,
inlet/carbs and the like (along with cam timing!), aren't in the "we-cheap"
budget dyno plan (if there is such a thing).
Remember you are paying for the time their machine is tied up on your job,
which probably *not* the same as the time you are actually running the car
on the rollers. You may find a dyno shop that klets you wheel the car away
and work on it yourself out of the way and only charges for the actual
running time - but I've not found one like that!!!!! (I wish)
cheers, Mike
----- Original Message -----
From "Jeff Boatright" <jboatri at emory.edu>
To: <spridgets@autox.team.net>; <midgetspriteclub@listbot.com>
Sent: Saturday, December 09, 2000 10:24 AM
Subject: rolling road prep
> Often I've read here and elsewhere that a rolling road analysis is
> good for setting up airflow systems (ie, carbs, inlet and exhausst
> manifolds, silncers, etc) and distributor curves. It seems to me,
> though that get peak performance out of one will require already
> having peak performance out of the other. It's a Catch-22. So, for my
> first trip to the dynometer, should I recurve the distributor, then
> play with airflow, or vice-versa, or a combination?
>
> TIA,
>
> Jeff
>
> _____________________________________________________________
> Jeffrey H. Boatright, PhD
> Assistant Professor, Emory Eye Center, Atlanta, GA, USA
> Senior Editor, Molecular Vision, http://www.molvis.org/molvis
> mailto:jboatri@emory.edu
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