Nick,
Thanks. That was exactly what I was looking for. Not being old enough to
remember such things, I had heard that fuel "then" was better than fuel "now",
and that the octane rating method had changed, making it hard to tell what you
were getting.
The tone of your message makes it sound like the car may become unbearable.
Maybe there was more to the Grassroots Motorsports article than I thought! The
chamber cc'd at 56 after the reface, and before any further grinding. With 87 mm
pistons, 0.013" deck height, and 0.020" gasket thickness, this gave me a
calculated compression ratio of about 9.9. After I radius in the intake
valves, grind the squish areas back in, and eyebrow the cylinder liners, it
seems like my compression ratio would drop substantially from this number.
Increasing another 3cc's would put me at a compression ratio of 9.5. Is
detonation a lot more dependent on combustion chamber design than compression?
Or does that small of a difference in compression ratio change fuel requirements
that much?
BTW, I have a Mallory Dual Point distributor with the adjustable advance curve.
This should make ignition tuning a little easier to figure out. I was also
planning on bypassing the old SU's altogether and going for Webers. It seemed
worth it for both tuneability and reliability, given what I'm trying to do.
One other thing: your advice from a couple months back was right on the money.
I was a little too liberal with the Wellseal, and this was keeping the liners
up. They now drop down right to spec. Also set up all the rods and all the
pistons on the same crank journal to get the rod variation. Found 0.007"
difference in length. I'm having the rod small ends rebushed with oversize
bushings and then offset bored to correct this.
BTW, what's 'grinding the tail off the cam' mean? Sounds like the legendary,
"old racer's demon tweak"!
Thanks again,
David Rupert
75701.242@compuserve.com
1967 TR4A (rigid axle)
1980 TR7 convertible
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