John,
I noticed that your were looking for information regarding
distributors from the list. I am not sure whether you got any useful
information that helps in a race motor scenario.
We use a distributor less crank-fire system on our race motors.
Before the crank-fired systems, I would:
1. Start with centrifugal advance only distributor housing.
There is no need for vacuum advance in a race motor.
2. I would look for a low centrifugal advance shaft. (on every
distributor shaft, under the points plate, there will be stamped number
from as low as 7 to as high as 18. This number refers to the amount of
distributor advance for that shaft. Double that for the amount of
advance the motor will see.)
3. Ideally you would like that number to be as low a possible.
4. If you have a 17 degree shaft, that means you will get 34
degrees of advance. If you want your race motor to stay under 32 degrees
of advance, you would have to start at 2 degrees of retard. It is real
hard to start a motor with to much or too little advance. The optimal
starting timing is with between 18 and 22 degrees of advance. In that
case you should look for a 9 to 11 degree shaft.
5. The next area of concern is the amount of wear in the
shaft/distributor. That will result in erratic timing between the
cylinders. Any more than 2 degrees of "slop" will be detrimental to
accurate timing.
6. The "curve" of the distributor, which is controlled by the
spring weight, was not very relevant. We wanted all advance to be in
before 3500 rpm. The race motor is geared so that you never go below
5,500rpm nor over 7500 rpm.
6. If you can run an alternate trigger mechanism to points, I
would go for the Pertronix optical trigger system.
7. If you can't go with a crank trigger, then a Pertronix and a
MSD 6A box would be the hot setup.
8. In case anyone else wants to go this way, I have a my former,
race ready distributor with a new Pertronix trigger system available
with MSD 6A box for $275.00
Tom Speed
Charlotte, NC
-----Original Message-----
From Deikis, John [mailto:John.Deikis at med.va.gov]
Sent: Wednesday, January 08, 2003 6:20 PM
To: 'Tom Speed'
Subject: RE: Spridget panhard bar
Tom: Thanks for sharing so much info. Some responses stuck in below:
> -----Original Message-----
> From: Tom Speed [SMTP:tspeed@carolina.rr.com]
> Sent: Monday, January 06, 2003 4:17 PM
> To: John.Deikis@med.va.gov
> Subject: RE: Spridget panhard bar
>
>
> Motor
>
> The only thing that we would have done
> differently would have been to use a cam with a little more lift. We
> use a 292 duration with .450" lift. You did not say whether you
> changed valve springs and retainers.
[Deikis, John] I used the heavier springs that came with the
new cam, but I used stock retainers. As for lift, do you think I might
save up for som 1.5 ratio rockers?
> You did not state whether you skimmed the top of the block, but
I'll
> assume that you did not and that you have a .010" deck height.
[Deikis, John] Actually, I did deck the block to take out a
little warpage. On assembly, I measured the deck height. But I got
.023". I figured my compression ratio using the following measurements
I took:
Bore: 2.822;
Head volume: 20.1 cc;
Deck feight: .023;
Head gasket bore: 2.906;
Gasket thickness: .038;
Piston dish: 6.5 (not measured; just taking then word of
Winners
Circle)
I'm no math whiz, so maybe I got the wrong answer on CR.
> With
> that and the rest of the information that you have given me, you are
> selling your motor a little short. It actually calculates out to a
> 11.5 to 1 compression ratio.
>
> The next bet would be a good rebuilt distributor
> with a Pertronix trigger
[Deikis, John] On the list for this winter.
> and a MSD 6A Ignition box mounted inside and on
> the underside of top of the passenger footboy.
[Deikis, John] Not legal but pretty common on the Spridgets
running with VSCDA. More of a financial constraint than an ethical one
for me, but I will consider it.
> With that you can safely
> run 32-35 degrees of total advance to get the most out of your motor.
[Deikis, John] I've been running 32 degrees with a Cooper S
distributor. Advance curve looks close to spec for this distributor--
meaning it seems to ramp up rather slowly, not reaching full advance
until about 4700 RPM.
> On
> the Dyno, we are showing a honest 105 hp with 85 hp at the wheels with
> a motor very similar to yours.
[Deikis, John] Have an hour of dyno time scheduled for this
spring. Can't do much in an hour, I know, but I hope to dial in some
timing; maybe try different dashpot oil weights or dashpot springs.
>
>
> Your next investment for the motor should be some reworking and
mods
> to your carbs. Will they allow you to go with 1 1/2" carbs? If not,
> you can have the 1 1/4's modified to pull a little more air
[Deikis, John] Will probably not get to that this winter, but
I'm sharpening my Dremel.
> an make sure
> you have the best needle for the motor.
[Deikis, John] That's been a problem. At $26 a pair, I can't
go to the dyno with a box full. I checked an SU needle profile chart on
the web and switched to the Cooper S needles. The needle stages are
close to stock at the top and bottom but a bit richer through the
middle. Can't say I noticed much difference, but I was concerned about
running lean with the stock needles and a ported head and LCB header.
> A good set of Air Horns/Ram
> Pipes does make a difference and We have tried several before we
> were happy.
[Deikis, John] What do you recommend? I planned to switch from
some Britsh foam aircleaners (Edlebrock style) to K&N and figured to use
their stub stack inside.
> The next step for the motor would be a good Light steel flywheel
and
> a AP/Tilton 7.25" competition clutch. You will be surprised at the
> difference they make in the acceleration of the motor.
[Deikis, John] I already regret not having popped for a F/W
lighter than the one I put in.
> I can help you
> with several, if not all of, these upgrades with either used parts or
> sources at good prices.
[Deikis, John] I'm all ears!!!
> Suspension
[Deikis, John] I used to run 800# springs but since I drive
this car on the street also, I just couldn't stand them. You could go
over manhole covers without losing a tooth filling. Do agree that my
suspension needs some more thought and work.
> We use the Rivergate
> limited slip on both a 3.9 and a 4.2 rear gear.
[Deikis, John] Has this proven reliable? What's involved in
fitting it to the dif? It's certainly priced in my range!
> This e-mail has become a treatise
[Deikis, John] I printed it out and highlighted it with a
yellow marker! Preach on with any more ideas, resources, or whatever.
You know the old cliche: Inquiring minds want to know!
Any chance you guys are coming to the MG Vintage Racers' Focus
Event at the Gold Cup Historics at VIR in June?
--John
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