2 BARREL RACING
My Lokar throttle cable was not up to the force the BG double pumper
requires for full throttle. The Lokar flexible cable won't take the
force - it just wrinkles up and I loose stroke.
In addition to the two NHRA mandated return springs and the
transmission's TV cable force that is very stiff at full extension,
the throttle system has to overcome the overly stiff coil springs on
the BG's primary and secondary throttle shafts. Plus the secondary
shaft is 100% actuated with only 50% primary shaft rotation so that
spring force is multiplied. And the secondary side's 50cc kit's
actuation force is also multiplied.
The Holley only has one shaft coil spring and it is weaker.
So I went racing with primaries not fully opening and secondaries
just barley cracked. It ran 7.44 anyhow with 1.60x short times all
day. That's better than last week in the heat with the Holley. Seems
like a good formula - let me write that down.
The track was in bad shape. Everybody was complaining about poor
traction and spinning off the line. Everybody except me that is. I
had good bite all day with some strong wheels up launches. Happy
Happy Happy!
In KOH I got the by on the first round and lost second round with a
double break out. I was on a 7.42 run that lap and I dumped - and
broke out anyhow.
The first lap's graph is attached. Note the longer plateau at 3200
on the launch. That's the tires taking more hit and digging in. The
lean spike at the launch is not too bad. It ran 13.5 AFR or so and
that was my target based on results with the Holley.
Noteworthy are the lean spikes at the shift points. Apparently not
vacuum carb related. So then why?
The graph shows the motor still pulling strong up to 5800, and other
graphs show it pulling to 6000, so there's more to give. It seems to
me that shifting higher should go quicker, spending more time in the
lower gears that offer the best acceleration. But I've been dancing
around these numbers for some time now and the data shows otherwise.
I always go quicker shifting at 5700 to 5800. Strange. Is that
because the RPM I shift down to has more effect than the RPM I shift
out of?
It will take some time to engineer a new throttle system. I'm
thinking a bell crank up under the dash or a cable over a pulley in
the firewall to make the bend.
Somebody at the track suggested I tie a string on it to supplement
the pull. I was tempted.
So I'll put the Holley back on for Thursday and we can see what the
RPM Air Gap is doing.
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