[Gmecm] Chevy 350 Carburated to TBI / TPI?

[Jason M.]

Just throwing in my experience with a low number rear gear and 700r4.

The vehicle is a 1982 caprice, 1973 oldsmobile 350 4bbl, edelbrock performer 
intake, 450 cfm holley (aftermarket replacement for mid 60's ford galaxie), 
1984 700r4 from a trans am, 2.56:1 limited slip rear from '86 caprice.  Body 
has been converted to 2 door el camino style vehicle with 4'' chopped top. 
it weighs approx. 4200 pounds, frame behind the rear axle was replaced with 
2x4'' 1/4'' thick steel tubing.

The torque converter is activated with a manual switch, and is deactivated 
with the brake light switch when the brakes are applied, and with the 
internal 3/4 shift switch that disengages the TCC during 3-4 and 4-3 shifts 
(it's stock in most 700r4's

In operation I usually leave the TCC switch on all the time after the engine 
warms up to ~150-160F.  Driving around town it can be in 3rd with the torque 
converter locked by 20mph and still accelerate.  Soonest overdrive will 
engage is 35mph.  So at 25mph engine rpm is about 900, at 35 mph engine rpm 
is about 800, idle rpm is 500 in and out of gear.  So I drive around town in 
over drive with the TCC locked all day.

Usually city fuel mileage is between 18-20, highway is usually between 
20-24.  Have seen 26mpg a few times.

1/4 mile times: 15.91sec 88.5mph.  that was with a slipping 2-4 band.  Right 
after Christmas a new band a "corvette" servo was installed.  Would expect 
something like a 15.8x time 89-90mph.

Anyways if your engine is making a lot of low end torque 2.40 rear gears 
won't be a big deal.  I would say change it over as soon as possible. 
Getting that T350 out of my car was the best thing I've ever done to it, or 
maybe it was the camaro bucket seats so I didn't have to duck my head down 
with that 4'' chop.

Jason.

----- Original Message ----- 
From: "Chris Reynolds" <red83brick at yahoo.com>
To: <gmecm at diy-efi.org>
Sent: Saturday, January 13, 2007 5:12 PM
Subject: Re: [Gmecm] Chevy 350 Carburated to TBI / TPI?


>I would use a TBI harness from a later model 1993-1995 Vehicle and use a 
>4L60E.   That way you can burn your own chips and adjust the shift points 
>accordingly.   2.46:1 with OD is not a problem in a lighter vehicle with 
>relatively short tires (aka Hotrod).   My Cadillac had a 307/2004r/2.53 
>gears.  My Fullsize van has 3.08 gears with its TBI 350/700r4 combo.   The 
>new Nissan Titans will run about 1,600 rpm @ 60 mph in their top OD of 
>their 5 spd automatic and return better than 20 mpg on the highway with 
>their 5.6 liter V8.   The 350 TBI makes great low-speed torque and will 
>cruise all day just off-idle.  I can pull some pretty good hills at 45 mph 
>in OD with the converter locked in the Van.
>
> BNRVL at aol.com wrote:
>
> Hello Jake , I will use the 350 auto presently in my 33 Dodge truck , as 
> it
> only has some 3-5,000 since rebuild an works OK . Eventually I will add a
> 700 R4 ,with a lock-up torque converter , and another rear ratio , as the
> present Duster 2:46:1 will not hndle the OD trans. , as I would have to 
> get up to
> 75 for it to kick in , so that's no good in the City driving scenerio .