V6 with automatic

I have a chance to get a 3.1 and automatic from a Camaro. Any thoughts on pros and cons of an automatic vs. 5-speed, and fuel injection vs. changing to a carb.

The pros will chime in on their preferences and whys. I'll be adding an automatic to the GT conversion - 700R4 or 4L60E (basically the same box). It'll be interesting to see the feedback.

Rick, most hot rod conversions I look at these days have done the automatic rather than 5 speeds or 6 speed.

You mentioned a difference in power output between the 3.1 and 3.4. What is the apprx. power output of both? Is either adaptable to a carb? If so, where would one source the parts and what size carb would be best? BTW, the engine I am looking at did have a 5-speed and still has the bellhousing and clutch, but the transmission is gone.

Thanks in advance,

Mike

I had a 86 S-15 with a crate 3.4 and a 85 Jeep Cherokee with a rebuilt 3.1 bored out .040 (3.2?) short block. Both had Crane cams . Didn't notice a whole lot of difference.Both auto trans,Jeep Mopar auto,GMC had 700R4.

BCC says
3.1L V6
The fuel injection manifold on this motor is too tall and will not fit below a standard MGB bonnet.

*************I DO NOT AGREE********************

The 3.1 V6 fits under my RBB bonnet with no problems.
The only thing I had to do is invert the throttle body on the the intake.

Carb vs EFI

I much prefer EFI because the motor runs better cleaner and more reliably. It seems senseless to me to retrofit a carb to an efi motor. Spend more for less performance.

STD vs Automatic

I'm considering an automatic for my BGT. I've got a crate 3.4 and a fresh automatic trans... I'm in my late 60's, live in a very hilly area, and think it's time for me to save what's left of my clutch leg.

Scot,

I did not recall you have the MPFI manifold.

Yes, they CAN fit but usually its far more work than that and is almost always done with a RBB, rubber bumper 75-80 model years like yours.

Many who have tried to fit have started with cutting motor mounts down which is only easily done in a rubber bumper car because the subframe sits lower. In chrome bumper cars, this requires quite a bit of work down there.

Others have additionally plained each manifold flange down- all 3 manifold bits 1/8" each to lower everything.

Some have used the Fiero top manifold with bits of the above to fit.

Others have continued to use the MPFI system but replaced the top two manifold bits with the single piece upper intake manifold from the 3.4L that is one inch lower than those earlier units anyways.

Is it possible to fit? Yes. Absolutely.
Is it more work at additional costs? Yes.

Scot, if you fit your MPFI manifold with NO modifications anywhere to any bit of the conversion, you are the only one I know that has to date. If anyone else has, I would like to hear of it. It is not just the very front but the entire manifold that had interference issues from when I studied them.

-BMC.

I'm looking at an automatic for the same reason mentioned above: My wife doesn't drive a stick, and this will be "her" car. Sometimes. :)

The selection of the 4L60E as one alternative was deliberate. It's electronically controlled, and depending on what ECU ends up in the car (which will be fuel-injected) it's a good choice. For example, MegaSquirt has code (post-Beta right now...?) that can operate this tranny through their auxiliary "GPIO" card.

Another alternative auto is Jeep AW4/Toyota A340.4 speed OD. Narrower than GM. Need Isuzu V6 bell for GM small V6. Can be adapted to manual shift(solenoid control).Supra Turbo puts 800HP through a built one for low 9 sec. quarter mile with Kevlar clutches and bands. Jeep 92-96(87-2002 can work) Cherokee 2WD with separate TCU are best. Even the Supra racers use the Jeep control box.

OK:
1. My 3.5 Fuel injected engine fits under the stock hood with no cutting anywhere.
2. The Street rods in the truck division weigh less than 4000# unless the are 1947 up. The difficulty is usually in the clutch linkage problem. ANY automatic trans can be made to out shift up or down any stick. Please remember Jim Hall and Chaparral sports racing cars A-B-C-D-E-F G-H J.
And this has been the case since the 60s SSA (super stock Automatic) and SS super stock classes in NHRA. Automatics were ALWAYS faster, stronger and ultimately the difference in classes was eliminated.
There are already 700R4 type automatics behind the 60 degree V6 that do not need ECU to control it.
Just as a note any of the T5Z series 5 or 6 speeds will handle any horse power you want to put in front of it including 454 big block ... so will a 700R4.
If you have any issues with this data call me, I have all of the details.
Skip Heller

Another nice thing about the 700R4 is that there's a large variety of gearing available for the box. You can almost mate the transmission to the rear-end of your choice. And if you don't like what you find in the bone yard, there's a large after-market in rebuilding/converting them.

For automatics, without going into long detail, the 700R4: (tu)

-BMC.

I have the 700R4 behind my 3.1 with carb. Have put 75000 miles on it in 5.5 years.
With the sock rear gear it ran 95 in the quarter. I now run a Ford 8 in with 3.0 gear. remember that an auto has torque multiplication in the torque coverter. I have a lock up switch on my auto. Just didn't like where the B&M kit locked and unlocked the converter.
With the 3.9 gear it ran 80 mph at just shy of 3000 rpm.
with the 3.0 it runs just shy of 2300rpm at 80.
I really like the auto trans.
I had to open up the fron of the tunnel and I did cut out the cross brace for ease of install and then bolted it back in.
BTW you can take the trans out with out removing the engine.
I used bill guzmans kit, but made my own trans support.

Steve