On Mon, 19 Oct 1998, Patrick McMullen wrote:
> Should I be concerned about using different strengh springs to control
> my mechanical advance?
To echo John's reply - no. The different springs allow for different
"slopes" of the advance curve.. a weak spring will give you a little more
advance at the lower end and a stiff one will give a flatter curve
towards the top end. At least I think this is how it works.
> I am using a combination of Triumph and Delco
> springs to get my current ignition curve. Will this cause rotor wobble?
No. Inless the dizzy bushings are worn.
> I was thinking that if one weight starts to open before the other that
> the balance would be off. Maybe cause ignition flutter at higher rpm's.
> Do you autocrossers use equal springs?
I actually have the stock distributor. Two of them, in fact. Mine have two
different springs.
> If so, how do you fine tune your
> advance curve? (trade secrets?)
You find a shoppe that has a distributor machine and have them play with
it. The springs in your Lucas 22D are quite a bit smaller than ones I've
seen for the general distributor like those seen on the Big Three V8's,
so before you can set this up, you should try to find a selection of
parts that the distributor tuning person can use...
What I found out this weekend past is that many places that fix cars
don't know a rats arse about recurving dizzys - or don't want to, or even
worse are probably prohibited from doing so because of the E - P - A. I
got a lot of "I can't touch that" responses. A lot. Like one shop of 15
that I called... really.
I think that since everybody has gone to more or less distributor-less
ignition systems, the art of curving a dizzy is going away.
FWIW, I did find a "race shop" that knows what to do. I'm bringing a
distributor to them later this week.
> Or am I worried about nothing?
This is a legit concern. I figured out this weekend that my advance
thingie on my TR6 distributor was frozen to the lower shaft. Yep, no
advance at all. Makes the power curve "real flat".
I also figured out this weekend that the built in limits of the advance
curve of the stock TR6 dizzy are pretty small - like 10 degrees, more or
less. If you are low compression (under 10:1) and you want the more ideal
curve (the Kastner book says 23 degrees total advance for low compression
performance cars) then you might have to reshape the weights or limit
blocks to get a bit more "swing" in there.
Note: John's (and Chip Bond's) Electromotive unit is really nice.
Drawback - relatively big money. You need to go to a crank trigger setup.
Advantage - if the crank timing is off, you have way bigger problems than
any ignition system can fix! That being said, I think the Electromotive
setup is really nice. Drawback - def. not for the vintage crowd.
;-)
I've also looked into the MSD setup - the 6AL plus the "advance unit",
module 8490, I think. I can look it up if you want to pull your Jacobs
box out ;-). But between the two components, your talking about $400 even
with a discount and you still need to trigger the thing somehow. I guess
that means a billit distributor, but I haven't seen one for a TR6 yet.
You could weld up a stock unit (or you don't oil the little screw
thingie like you're supposed to - like I didn't - Doh!) to get a fixed
timing point for your trigger - but anything driven off the cam is
subject to the possible irregularities there... so a crank trigger is
really the way to go if you want rock solid timing. And the crank trigger
hardware is not cheap, at least that's what I've found from my inital
foray into the topic.
> Pat in NC
Bob in lobsta land.
-------------------------------------------------------------------------------
Bob Lang Room N42-140Q | This space for rent.
Consultant MIT Computer Services |
Voice: (617)253-7438 FAX: (617)258-9535 |
-------------------------------------------------------------------------------
|