Engine -Tranny Transplant
Thread Starter
Burning Brakes
Joined: Jul 2004
Posts: 783
Likes: 38
From: Mankato Mn
Engine -Tranny Transplant
I'm doing a frame off restore on a 68 convertable. Right now it has a BB with a M 21 tranny. I recently picked up an 85 with the L98 engine & the 4+3 tranny. I'm concidering puting this in the 68. I just saw a 75 at a car show last weekend with the L98 engine in it, but it had an automatic in it. I'm guessing he just bolted it up to the L98 without many problems. Does anyone have any insight or am I insane. The 85 is in really tough shape so I plan on parting it out anyway.
Safety Car
Joined: Dec 2005
Posts: 4,270
Likes: 20
From: Central Michigan
Keep the BB. Take the L98, wiring, computer, trans, etc. and save it for another project(I have an L98 in my truck, the low end torque is great for towing), either part out the rest or have the local wrecker come get it
Drifting
Joined: Nov 2005
Posts: 1,601
Likes: 4
From: Texas
I looked into trying to adapt a 4+3 to an earlier model SBC... I found
after much searching that no one is offering aftermarket support for
it.... the problem stems from the electronic controls of the overdrive.
L98 heads flow less than 200cfm... and the stock L98 TPI will limit
the amount of airflow you can push through the heads even if you get
some that flow better..
If you're trying to put together a torquey driver that gets decent
MPG.... I think you're doing fine as long as you have the skills to
work on the TPI and Trans yourself.....
You could sell your 4+3 and L98.... keep the electronics off the
TPI and mate it with an Edelbrock upgrade system that uses the
carb style throttle body and port injection.... this would give you
a set up that could breathe...
I'd keep hp under 450 ..get a World Class T5 w/GM conversion trans
and have a HP capable EFI and a mechanical overdrive trans...
mileage and performance.
after much searching that no one is offering aftermarket support for
it.... the problem stems from the electronic controls of the overdrive.
L98 heads flow less than 200cfm... and the stock L98 TPI will limit
the amount of airflow you can push through the heads even if you get
some that flow better..
If you're trying to put together a torquey driver that gets decent
MPG.... I think you're doing fine as long as you have the skills to
work on the TPI and Trans yourself.....
You could sell your 4+3 and L98.... keep the electronics off the
TPI and mate it with an Edelbrock upgrade system that uses the
carb style throttle body and port injection.... this would give you
a set up that could breathe...
I'd keep hp under 450 ..get a World Class T5 w/GM conversion trans
and have a HP capable EFI and a mechanical overdrive trans...
mileage and performance.
