John,
I thoroughly agree with your first decision to convert to a wide ratio
transmission. That is by far the best all-around performance modification and
'bang for the buck' I did to my Tiger... better mechanical leverage in the
first 3 gears where I want it, while still maintaining low rpms at highway
speeds. I went even further and installed a 2.90 first gear from David Kee
Toploaders in Texas in place of the standard 2.78 first gear. I also kept my
2.88 rearend for the same reason you suggest, long distance driving. I
recently bought a set of 2.72 rearend gears for another 6% lower highway rpms
(not yet installed). This will not appreciably affect my 'off the line'
performance with my 2.90 first gear. Most Tiger people are unaware that the
Tiger differential can accommodate 2.72 gears. With this setup I will start to
approach the rpm range of the 5 speed conversion without the major price hit
of a 5 speed, no modification to the transmission tunnel and
I get a 6% overdrive on the higway compared to the 2.88s, all with standard
off the shelf parts. The transmission swap cost me ~$475 for the new wide
ratio gears, I sold the old close ratio gears for ~$250 and the 2.72 ring and
pinion cost $75. So for $300 I got a wide ratio transmission, a low first gear
and a 6% overdrive.
Engine upgrades can consist of inexpensive add-ons to expensive bottom up
modifications. You can easily and fairy cheaply install a performance intake
manifold, increase the size your carburetor and update your ignition, but
unless you reduce back pressure, your engine will not make much use of those
upgrades. Back pressure robs performance. What goes in, must come out... and
the more efficiently, the better. To me the second and most obvious
performance improvement is a good set of headers and commensurate flow through
dual exhaust system. Reducing back pressure makes you engine run
more efficient and improves performance AND mileage.
Third upgrade would be modern heads, not so much for the aluminum (better
cooling), but for the improved combustion chamber and increased flow capacity,
especially on the exhaust side. The stock Ford heads are very restrictive on
the exhaust side. If you do upgrade the heads on your 289, stick with the
1.90" intake valves, not the 2.02". Typical engine building performance
mistakes are oversize carbs and oversize valves. Once again, what goes in must
come out. You will need to verify valve to piston clearance.
Keep you dual plane intake manifold. It is ideal for street performance where
you need the low end response off the line. With improved heads, your 600 cfm
carb with vacuum secondaries will be fine for the street. Personally I run a
600 cfm double pumper Holley with manual secondaries and 2.02 intake valves on
my 400+ HP 331 stroker and find that it is very responsive, i.e. I am traction
limited. 600 cfm on a stock 289 is way too big. I believe Tom Monroe's book
has the formula for calculating carburetor size.
I upgraded to an electronic distributor for better high end performance. Since
your not running high rpms with a stock bottom end, your 'dizzie' is fine. At
some point you may want to upgrade for performance, reliability and lower
maintenance.
Just my 2 cents worth,
Gary
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