> I would like to start an on-list discussion of octane, timing and
> performance.
> I have a stock 1971 TR6. I currently run premium gas, which is
> what is recommended.
Man, are you wasting your money. I don't think any of the US spec TR6's even
reached 8:1 compression....more like 7.75:1 max. They run just fine on 87
octane.
When the TR6 was new, (and I think still to this day) the reported octane
number in the UK was actually the "research" number. You may have seen the
octane rating on US pumps listed as the (r+m)/2. The r is research, and the m
is motor. They actually have a special little single cylinder engine that is
used to determine motor octane by advancing the timing to the detonation point.
Research number is determined in the lab (and typically higher than the motor
number).
> With all the vacuums, etc attached I time it at 8 BTDC.
So plug off your vacuum and run it at 10 - 12 BTDC. They run a lot better.
I've had plenty of TR6's and set them all up that way.
> No ping, runs great.
> My understanding is that lower octane gas burns faster and a
> little hotter, but at 20 cents/gallon cheaper it is tempting to
> switch to the lower octane and retard the timing until it doesn't
ping.
No need to retard.....advance until it pings, then back it off a bit, or just
set it at 12 BTDC and go for a drive.
Happy motoring!
Chad
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