To the OP
a couple of tenths maybe, if it hooks
what is the end use for the car ?
how much freeway/open hwy driving will you be doing ?
how much can you put up with ?
if you just putz around town, stoplight to stoplight bandit
it will make it perform better, in the 1st 330ft hands down,
that's where you make up most of the lower ETs, between 60' & 330'
that's
if it hooks up
then it's no big deal, go with the 4.10:1
heavy *** cars either need a shitload of HP & TQ, like 800+
or gear multiplication/the torque advantages from it,
with steeper gears to get them to move off the line faster/easier
what is it you want to do ?
or a compromise 3.73:1 or a 3.90-3.91:1, each would help a lil'
it appears to have like a 29" or taller tire now
https://www.wallaceracing.com/gear-speed-calc.php
(
enter your tire diameter assuming it's 29" tire diameter
& a 4.10:1 gear & in 4th (or 3rd 727tf),
final trans gear ratio stock is 1:1 in high gear (no OD)
at 73.65 MPH it's 3,500rpm at 63.13 MPH it's 3,000rpm,
with a 3.54:1 gear it's 3,000rpm at 73mph
it's just like having a 27" tire (295/50/15) 3.91:1 gears & 1:1 final gear,
same RPM almost)
it's not like you have a 25" tall tire on it...
Hell even a 295/50/15 is 27"+
it's a Dana-60 & you can get most any gear combo out there
if you still want the 4.10:1 & do a lot of freeways or open road traveling
then maybe go to a 'Gear Venders' Under/Overdrive $2,900+
ish - $3,100+
ish
+ shorten your driveshaft
or other type manual Passion 855, TKO, TKX, Doug Nash, Richmond,
(
add a pilot bearing, a decent clutch, bell-housing, flywheel, shifter & linkage,
pedals & linkage, z bar etc., throwout bearing & linkage/fork {or hyd}, driveshaft,
and probably a cross-member too )
or other OD transmission combo setup, it adds up
&/or even a lock-up converter with an auto
(
later 70's strating like 77-78-ish 727tf IIRC)
will help some, the lock-up converter for a performance combo, won't be cheap
like I asked above '
what is the intended/end use ?',
what do you want to accomplish, with a LOWER gear change
most people
do that/it to go faster, in a
shorter period of time/distances
they aren't generally worried about fuel mileage or noise at freeway speeds
they do it for/from a dead stop to max acceleration performance,
as quick as they can,
over a shorter distance
if you are, worried about that other stuff
(
mileage & noise/rpm at freeway speeds)
then maybe need to go in a different route
or visa versa, Go to a lower numerical #s
(
IIRC a 3.21:1, they may make a lower #)
to
make it stretch it's legs for the open hwy, 150mph+...
(
Or an OD of some sort, you can have the best of both worlds, it's only money
& it's all relative, to how fast you want to go ? & where/how you want to do it ?)
1/4 mile acceleration contest
(
for serious performance guys, you should include the tire size in that equation too)
a 10:1 combined ratio in 1st gear = your 1st gear trans ratio x your rear gear ratio,
example 2.45:1 (
1st gear) x 4.10:1 (
rear gear) = 10.045:1
is a good rule of thumb, for a decent acceleration contest
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