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Circuit Trackday with the '73 Dart

Posted: Fri Apr 19, 2019 3:11 pm
by BigBlockMopar
Last sunday I was able to put my Dart on the Circuittrack for a 20 minute blast around the 4.2km racetrack.
This was my first time on a track and I wanted to get some feel of how the car performs at (some) higher speeds.
Being my first time, one has to learn to 'read' the corners and how fast you can drive through them. But the circuit is located on the westcoast dunes, so it's not easy to prepare for corners when they are behind a hill/dune.

I'm also happy to report the Impco vaporizer and 425 worked without issues during the 4 laps I was able to make.
During the 4th lap I started smelling whiffs of ATF-oil. Thinking a cooler-line was leaking I decided to call it a day and head for the pits. Turned out ATF was spilling out the of pass.side filler tube during hard left cornering.

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Re: Circuit Trackday with the '73 Dart

Posted: Fri Apr 19, 2019 4:38 pm
by storm
I am so jealous, that would have been interesting and fun. Did you do any logging? What times did you pull? Valiants (Australian version of your car) didn't handle all that good from factory and took alot of work and money to get them to stick to the road, doing that in the late 60s early 70s would have been a white knuckle ride. Our cars changed in 1971 to the larger Charger but the old Pacer was a great car in its day.

Re: Circuit Trackday with the '73 Dart

Posted: Fri Apr 19, 2019 6:11 pm
by BigBlockMopar
I have a little better write-up on my site in the signature, but here's a short clip from trackside where someone happened to shoot some vid of my car in ahum "action"...

https://www.youtube.com/watch?time_cont ... pvFTPwUlEI

I've also shot some in-car video myself with a cool iPhone app called TrackAddict.
Very app where it uses the iPhone GPS-signal to read its location on the track, and it even starts timing the laps the moment you cross the start/finish line.

Here's the complete session from inside the car, including the first lap spin-out... ;)
Click the full-screen-icon for higher quality image.
Don't fall asleep though... 8)


Re: Circuit Trackday with the '73 Dart

Posted: Sun Apr 28, 2019 2:41 pm
by gottago
Hey pretty cool! The old dart looks and sounds pretty good especially given what you are running along side with. Are you happy with how the engine turned out now that you have had some time to work the bugs out?

Re: Circuit Trackday with the '73 Dart

Posted: Mon Apr 29, 2019 5:24 am
by BigBlockMopar
The engine itself runs nicely.

However there are still a couple of things I want to address or 'upgrade' again.
First is the camshaft.
It's a CompCams XE256H, which I converted to a mechanical cam with adjustable rockers, because the hydraulic lifters kept collapsing. I will never build another engine with hydraulic lifters.
I have a set of solid lifters with 'EDM'-oiling holes at the bottoms, ready to be installed.
Actually I would rather like to have a slight 'lopey' idle, but that would mean a less efficient engine at lower rpms.

Second is the oilpressure. As the engine warms up, the oilpressure becomes low, like about 10psi at idle. Even with the 10w60 synthetic Lucas oil I'm currently running and the high volume oilpump.
I "hope" the current lifters are the culprit here as their oilbands are located fairly high on the lifter bodies, possibly spilling and bleading off oilpressure at lower rpms.

And while I'm working on the engine, there's a pair of aluminium heads waiting to find their way on the engine as well.
Plan to do a proper valvejob on them first, mill them enough to get the compression ratio up again and then along with its larger valves and ports hopefully some more power will find its way into the driveline.