At 01:41 PM 1/19/98 -0500, you wrote:
>> I have just finished a basically stock restoration. The only thing I
>> changed was a 3.07 rear and 205 60 tires on 13in rims. My tack shows
>> 4K at 70mph. The engine sounds kind of busy but not overly.
>>
>> My questions are:
>> Is my engine really turning at 4K?
>> Can a 260 run at 4K all day without damage?
>> Is the information in Performance Tuning Sunbeam Tiger pg. 65-67
>> correct?
As there has already been a couple of responses on the 4K question .
(Which I more or less agree with) I will comment on pages 65-67.
The general info describes speedometer error, changing of speedometer
drive cable gears and transmission ratios. I believe that the information
on the transmission ratios is correct. The 4 or 5 other tables are probably
correct for the exact tire size indicated and the rear end ratios specified;
however, you stated that you have a 3.07 rear end and 205-60 tires. Your
exact tire size is undefined as various tire vendors have slightly different
actual sizes for the same 206-60 lable. Recommend that you compute
the mph per rpm yourself to get accurate numbers. The other responses on
the 4K question have the equation. I recommend that you mark the tire
and ground contact point, roll the Tiger for 5 revolutions of the tire and then
divide the distance by five to get a fairly accurate tire circumference.
Note that the equation is linear and therefore if you use the tables and
multiply the mph by the ratio of "table" rear end 2.88 to your rear end 3.07
i.e. 2.88/3.07 then the results will be correct for the table's 24.5" tire.
Example: at 2000 rpm, table states 51 mph. (2.88/3.07) ( 51) = 47.84.
Now if your tire's rolling diameter is 23" then do:
(23/24.5)(47.84) = 44.9 mph.
Remember that if your speedometer reads fast then you might get fewer
speeding tickets if you don't know that fact.
Jim Barrett Tiger II 351C and others
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