Need tech info or chevy PU bbs

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I just got my 1971 Chevy short bed stepside on the road, I want to do an engine swap, it has a 250 staight six with a column shift 3 speed, two wheel drive, I did a search but came up empty, here's what I want to do ;

Swap the straight six and three speed out with a 4.3 L V6 and 4 speed automatic, specifically I want to know what engine mounts and crossmember I need to do the swap, anyone know or does anyone know of a BBS that deals with such issues ?

Thanks
 

I'm looking for gas mileage as well as torque ;)

The V6 is coming out of a 1989 Chevy S10, it has throttle body F.I. and a overdrive 4 speed automatic.
 
B

Blain

Lifer
Oct 9, 1999
23,643
3
81
"I'm looking for gas mileage as well as torque"

Don't forget that rear end. Your old 71 probably has a lower gear ratio than the 89 S10 that the motor came out of. Good for hauling, but killer on gas mileage. :Q


I predict 12 MPG at best for your old 71. ;) I've had several old chevys, with V8's & straight 6's. 12 MPG was tops I could ever get out of any of them. But I never changed rear ends.
 
D

desertdweller

Senior member
Jan 6, 2001
588
0
0

Roger,

The 4.3L has been described as a 350 with the two rear cylinders cut off. The block
will use the same mounts as a 350 but will probably have to be moved back a couple
of inches to do the swap. I don't know about the cross member. You may have to
fabricate one.

You might consider just doing a v-8, I've seen almost complete vortec fuel injection
system takeoffs for resonable prices. With that and a decent cam grind you'll probably
get the fuel mileage you want.

As far as a BBS goes, the only board that I go to that involves mechanics anymore is a
boating board, but alot of those guys do cars also and will probably answer an
OT post on your project.

Here is the link if you want it.

OffShoreOnly.com


DD
 
C

cavemanmoron

Lifer
Mar 13, 2001
13,664
28
91
Originally posted by: desertdweller
Roger,

The 4.3L has been described as a 350 with the two rear cylinders cut off. The block
will use the same mounts as a 350 but will probably have to be moved back a couple
of inches to do the swap. I don't know about the cross member. You may have to
fabricate one.

You might consider just doing a v-8, I've seen almost complete vortec fuel injection
system takeoffs for resonable prices. With that and a decent cam grind you'll probably
get the fuel mileage you want.

As far as a BBS goes, the only board that I go to that involves mechanics anymore is a
boating board, but alot of those guys do cars also and will probably answer an
OT post on your project.

Here is the link if you want it.

OffShoreOnly.com


DD
Click to expand...

BBS? Big Block??

I have a 4.3 in a 90 k10 with a 5 speed

it is an ok motor,but i would rather have a 5.7

the TBI units have a common problem of the pressure regulator springs fatiguing/breaking

make sure to check the spring,it only takes about 15 mins time.


http://www.dstutz.com/caprice/25cent.html

 
D

desertdweller

Senior member
Jan 6, 2001
588
0
0
Originally posted by: cavemanmoron
Originally posted by: desertdweller
Roger,

The 4.3L has been described as a 350 with the two rear cylinders cut off. The block
will use the same mounts as a 350 but will probably have to be moved back a couple
of inches to do the swap. I don't know about the cross member. You may have to
fabricate one.

You might consider just doing a v-8, I've seen almost complete vortec fuel injection
system takeoffs for resonable prices. With that and a decent cam grind you'll probably
get the fuel mileage you want.

As far as a BBS goes, the only board that I go to that involves mechanics anymore is a
boating board, but alot of those guys do cars also and will probably answer an
OT post on your project.

Here is the link if you want it.

OffShoreOnly.com


DD
Click to expand...

BBS? Big Block??

I have a 4.3 in a 90 k10 with a 5 speed

it is an ok motor,but i would rather have a 5.7

the TBI units have a common problem of the pressure regulator springs fatiguing/breaking

make sure to check the spring,it only takes about 15 mins time.


http://www.dstutz.com/caprice/25cent.html
Click to expand...



BBS as in Builitin Board Service. Typically, BBC would be Big Block Chevy.


DD
 

I predict 12 MPG at best for your old 71. I've had several old Chevy's, with V8's & straight 6's. 12 MPG was tops I could ever get out of any of them. But I never changed rear ends.
Click to expand...

I'm getting 16 now with the straight six.


Roger,

The 4.3L has been described as a 350 with the two rear cylinders cut off. The block
will use the same mounts as a 350 but will probably have to be moved back a couple
of inches to do the swap. I don't know about the cross member. You may have to
fabricate one.

You might consider just doing a v-8, I've seen almost complete vortec fuel injection
system takeoffs for resonable prices. With that and a decent cam grind you'll probably
get the fuel mileage you want.
Click to expand...

As far as a BBS goes, the only board that I go to that involves mechanics anymore is a
boating board, but alot of those guys do cars also and will probably answer an
OT post on your project.
Click to expand...


I have had several full size Chevy trucks with both 4.3 and 350 engines in them, no comparison, the 4.3 gets superior mileage ;)

Thanks to everyone for the very good links :):)



 
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