Re: AMC 4-cylinder in a Spirit (Revisited)

["Jim Blair" <carnuck@xxxxxxxxxxx>]

A: A 2wd Comanche or Cherokee daily driver would be pretty much in the same 
class for weight and use as an AMC car. Most trucks run deeper gears for 
several reasons. Running bigger tires for carrying bigger loads is one of 
them but the 205/75/15 the Comanche came with matches car tire size. I have 
come across a couple 4 cyl 5 speed Eagles with 4.10 gears as well. The AMC 4 
cyl is somewhat different than the Iron Dookie. It seems to make good power 
and fuel economy at a higher RPM than the GM motor of the same size. When 
lugged, the 4 cyl EATS more fuel than when it is in it's power band.
   You need to match the gearing with the power band and transmission (auto 
would get taller gears). I would put a Chevette motor into Vegas for awhile 
(there were tons of nearly mint, nearly free Vega's and Astre's and 
Chevettes with rotted out shock towers and banged up bodies) and discovered 
I needed to gear match the motor for the extra weight.
   The Jeep trans would be either .70 or .75 5th gear. Much better suited 
for lower gears.


From: TABunsey@xxxxxxx
Subject: AMC 4-cylinder in a Spirit (Revisited)
To: mail@xxxxxxxxxxxx
Message-ID: <ADVANCES62ZbLAX3cf3000001d8@xxxxxxxxxxxxxxxxxxxxxxx>

Frank & Company:

Please pay attention to my entire post, AND to the original question 
concerning gearing.

(1) I don't argue that the 4-cylinder in a TRUCK would have 4.10 gearing.

(2) But he doesn't want to put the engine in a truck; he wants to put the 
engine in a CAR. FOR GAS MILEAGE!!!!

We aren't talking TRUCK gearing; he wants to know what PASSENGER CAR gearing 
to use. We're not talking about load hauling a ton of wood or whatever in a 
pickup TRUCK, we're talking about a passenger car rated at about max 700 
pound payload (see owner's manual for details).

What I am saying is that when AMC used a similar sized engine in a Spirit, 
these were the rear end ratios they used.

Historically, trucks use deeper rear end gearing than the same engine in a 
passenger car. You know this, I know this.

The guy raising the issue wants to put this engine in a passenger car. He 
isn't going to haul firewood, or plow his driveway, or go off road with it. 
He is going to drive the car on the highway!

As I recall, the 1982 Spirit with the IRON PUKE and the 5-speed was rated at 
37 mpg, highway. With a 3.08 gear. And a .85 5th gear (overdrive).

THIS IS WHAT IS WANTED. Mileage!

NOT pulling Jeeps out of ditches!


Tom Bunsey