Cam tech notes from 'fest drive (before I forget)
10-29-2005, 04:31 PM
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Cam tech notes from 'fest drive (before I forget)
I drove my US '81 automatic (3" single pipe exhaust, no cat, gross weight about 3300lbs with me and all tools, parts, spare, etc.), roughly 2500 miles on this trip, here's what I observed.
I drove at ~3000RPM (80MPH), used Chevron 87 octane, with static (26) degrees ignition, (2) degrees cam retard on the way down, and (2) degrees cam advance while there*, and on the return.
19-20.5 MPG (my Chevron card is still warm)!
Average mileage was the same, but throttle response is much, much better with the advance. I theorized that cam retard would help with mileage, but at the speed I was travelling, it made no difference. Perhaps with stock exhaust, and/or higher speeds, or more ignition advance with higher octane?
Stripped down for the fun run, at around 3200 gross with the cam advance, I had no trouble keeping up with more powerful cars, and could easily keep a line through the curves! Takeoff is still dogged, and speeds over 90 would be trouble, but second gear hits the sweet spot from 3000-5000rpm.
*I immediately restored my usual advance, to keep up with the crazy LA freeway traffic. BTW, it's a blast driving at night there, it's like a video game!
I drove at ~3000RPM (80MPH), used Chevron 87 octane, with static (26) degrees ignition, (2) degrees cam retard on the way down, and (2) degrees cam advance while there*, and on the return.
19-20.5 MPG (my Chevron card is still warm)!
Average mileage was the same, but throttle response is much, much better with the advance. I theorized that cam retard would help with mileage, but at the speed I was travelling, it made no difference. Perhaps with stock exhaust, and/or higher speeds, or more ignition advance with higher octane?
Stripped down for the fun run, at around 3200 gross with the cam advance, I had no trouble keeping up with more powerful cars, and could easily keep a line through the curves! Takeoff is still dogged, and speeds over 90 would be trouble, but second gear hits the sweet spot from 3000-5000rpm.
*I immediately restored my usual advance, to keep up with the crazy LA freeway traffic. BTW, it's a blast driving at night there, it's like a video game!
