| Gen III For Dummies|
| A Beginner's Look at Swapping an LS-Series
Engine into a Classic Truck|
| By Jeremy Cook|
|So you're tired
of tuning your carb and think you're ready to move into 21st-century technology?
And you think that the new GM Gen III engines might be just the ticket.
It's pretty tempting to run out and grab one and jump right in, but did
you know that the mounts on the side of the block are different? Or that
there may not be a lever on the throttle body to attach your accelerator
cable to? Or that there's pretty much no way you're going to get your truck
running right without purchasing a harness and reprogramming the computer?
None of this is meant to scare you off It's quite the contrary, actually.
Since the swapping of these engines into earlier vehicles is becoming so
popular so fast, we thought we'd take a look at just what's involved, as
well as what's available to make the job easier. The
LS series of engines from GM, commonly referred to as Gen III engines, began
production in 1997 with the aluminum-block Corvette 5.7- liter LSI (its
higher performance sister is the IB6) with similar versions in the F-bodies
(Camaro and Firebirds). The cast-iron block 4.8-liter, 53-liter, and 6.0-liter
entered production in the '99 truckline. The top dog of the truck engines
is the 345-horse Cadillac Escalade engine, which is essentially the 6.0-liter
with the LS6 heads and other components. Although the basic design is the
same, we quickly learned that there are several small differences among
them. We will concentrate more on what it will take to actually perform
the swap and not on extracting every possible horsepower (something we will
be looking into at a later date). We focused on the '63-72 GM truck chassis,
but most of the principles discussed are the same for just about any vehicle
with two framerails and a hood.
FINDING THE PERFECT BEAST:
Obviously scouring wrecking yards is going to be the easiest way to find
what you are looking for. We'll tell you up front, the aluminum LS1s are
already not the easiest engines to find, and the price for a low mileage
unit with the trans still attached will normally run at least $4,000. But
just think of how many trucks GM have sold since late 1998. Soon the wrecking
yards will literally be filling up with the cast-iron versions, and they
still have all the potential in the world to make additional horsepower.
Sure there's a weight difference, but we build trucks, remember? Anyway
we checked with owner Dave at Goldenwes truck Wrecking, and the going rate
for a complete 4.8-or 5.3-liter with low mileage (say30-40K) and a 4L60E
transmission attached is in the neighborhood of $3,200. Now figure the price
to build a nicely equipped early small-block and back it with a 700-R4,
and you'll quickly see why these engines are starting to look good. Of course,
LS1 engines are available as crates from GM Performance parts, and there
are companies like Street & Performance that eliminate the running-around
part of the equation by keeping a good stock of low-mileage engines that
can be equipped to suit your needs. Also, wrecking yards may still be dirty,
but the smart ones have kept up with the times and can be accessed online.
may have listings for their complete engines or simply respond to inquiries
by e-mail, but it's entirely possible to have a Gen III engine delivered
to your door without ever leaving the garage. THE ISSUES ARE MOUNTING:
To get an idea of how to mount up one of these engines, we Called
a few companies, namely Total Cost Involved and Street & Performance,
visited a shop or two that regularly installs LS engines in street rods,
and even checked out a couple of do-it-yourselfers. But everyone we checked
with basically had the same idea, which was to fabricate some sort of adapter
plate that bolts to the block. Then an early-style Chevy mount would bolt
to the plate. From there, the possibilities are endless, yet the end result
was always the same: to have something for the early mount to slide over
and the bolt to run through it horizontally from front to back, The general
consensus was to have the engine sitting as close to where the old small-block
sat as possible. Also, Chevy engines run on the four-degree rule. That is,
the engine usually sits on a four-degree downward angle from front to back.
Even though the LS engines sit at a zero angle in the Vettes, the four degrees
is recommended to help with your pinion angle.
In some trucks, it may be feasible to set the engine back a
bit further to help the accessories or even the stock mechanical fan clear.
But something to consider is that switcing to elecnic fans or a push fun,
or even moving the accessories around, may be easier than relocating the
engine mounts or modifying the crossmember. The A/C compressor and power-steering
pump on the truck engines are mounted very low on the engine and could present
a problem where the frame pinches as it reaches the front There are also
balancers that run closer against the block than others; the Vette is a
fu1l 1- l/2 inches shorter than that of the trucks. The best source we found
for these types of issues was Street & Performance. Not only do they
have a vast knowledge of everything Gen III, they have a huge inventory
of both OE and their own custom brackets and pulleys to help overcome any
clearance issue you might have. Of course there's one factor that may dictate
exactly where you will be mounting your engine: the oil pan.
|Corvettes, F -bodies, and trucks are all different, yet interchangeable,
which is good news. More good news is the fact that in both of the '63-72
swaps we saw performed, the truck oil pan couldn't have contured around
the crossmember better. Nonetheless, while speaking with Scott Leon at GM
Perfonnance and Mark Campbell of Street & Performance, we learned that
there are several transplants in muscle cars that require modification to
Finally, we keep mentioning using the 4L60E transmission that
came behind nearly all of the cast-iron LS engines. One reason is the nice
price break you usually get by buying the two together. Another is the fact
that unless you are running the 4L60E, you will have to change the Flexplate
and possibly order a different wiring harness, as the cormections for the
4L60E are usually included in the harnesses that are available. But just
as everything else we have discussed, there are companies like McLeod Industries
and Advance Adapters that offer components to enable mating the LS engines
to a variety of earlier transmissions, both automatic and manual. The actual
mounting of the transmission to the crossmember could't be easier. In some
cases, it may be necessary to use a universal crossmember from somewhere
like Classic Performance Products. In some trucks, you can get away with
easily redrilling the mounting holes on the stock crossmember. Undoubtedly,
the driveshaft will have to be shortened this is an area where you will
have to rely on the professionals. And, just for the record, different shops
measure for driveshafts in different ways, so call ahead any time you have
to shorten or lengthen a driveshaft. Well, now that the engine is solidly
mounted in place, let's take a look at what else is involved to get you
back on the road.
HARNESS THAT ANGER:
If you've heard anything about installing a Gen III engine
in any vehicle, it's that sorting out all of the electrical connections
for the coil packs and multitude of sensors can be a nightmare. And if you're
hoping that you may save a few bucks and figure it out yourself, it will
be a nighmare. Moreover, if you don't send the computer out to a qualified
shop for reprogramming, the engine simply will never run at its full potential
if at all. Companies like Painless Performance, TPI Specialties, and Street
& Performance pride themselves on being ahead of the curve for these
types of swaps, and each offer a complete harness that will make the install
worlds easier. Other than four leads and grounds, most of these kits are
truly plug and play and have all of the weather-pack plugs already attached
with all the relays and the diagnostic link at the correct length with detailed
color-coding and labels. And speaking of grounds, it was stressed to us
several times just how important proper grounding of the engine is. The
recommended method is from the battery directly to the engine or transmission,
and then to the engine to the frame and the frame to the body.
Each company had different methods of reprogramrning the
computer, but the general idea is to remove all of the programs that will
not apply once the engine is transplanted. One of the most important of
these programs is the Vehicle Anti Theft (VAT) device. Another has to do
with the removal of the charcoal canisters for fuel vapors. Finally, similar
to aftermarket re-programmers, the correct transmission type, gear ratio,
and tire diameter is inputted to help you get the most out of the engine.
On '74 and earlier vehicles, emissions programs can be removed without effecting
the clean-running LS-series engines.
FUEL FOR THE FIRE:
Running the Gen III engine requires the use of a high-pressure
fuel system equipped with a return line. The most common solution is to
install an in-tank fuel pump that accepts a fuel line. Once again, the manufacturers
are ahead of the curve, as Street & Perfonnance works closely with Rock
Valley to make available several-style fuel tanks with the in-tank fuel
pump already installed. Another option that we have seen is to install a
frame mounted-type fuel pump with the proper pressure and that allows for
a return line.
ACCELERATING TO THE FINISH:
Most of the Gen III engines have cable-operated throttle
bodies. However, some of the Vettes and all the trucks beginning in '03
are "drive by-wire" or electronic throttle bodies. While the current
solution is to convert the throttle body to the earlier one, Street &
Pelformance informed us that they are working on a system to work with the
drive-by-wire setup because it is here to stay. Well, there
you have it all the key issues to prepare for when you make the jump into
Gen III. Be sure to check out the Web sites of the aforementioned manufacturers
to see which of their products are for you. There is a wealth of knowledge
contained on those pages that we could not even begin to tell you about
here. But if we learned anything with this, it's that "winging it"
simply won't work. The power and technology is waiting. Us regular guys
just need to catch up.
Here is the most plentiful source of Gen III engines there
is: wrecked '99-up GM trucks and SUVs. We've seen 'em with as little as
3,000 miles on them.
The '99-up truck oil pans are a great fit with the crossmember
in '63-72 GM trucks. It couldn't be a better match if it was planned.
The first obstacle to overcome is getting a mount to fit
the new-style bolts on the block.
Here's a F-body pan that had to be trimmed extensively
for use in an early muscle car.
The setup that Total Cost Involved recommends is their
polished aluminum adapter plate. It's super thin thanks to countersunk bolts,
and it accepts the early-car-style Chevy mounts. Their frame mount is a
universal piece. It can be trimmed down as far as needed to fit and then
welded to the frame.
Although the stock crossmember can sometimes be moved or
redrilled, this crossmember from CPP, made specifically for '63-72 GM trucks,
makes the job much cleaner. It will slide wherever you need it to before
bolting it in.
Here's a Total Cost Involved adapter in action. Here, the
owner simply welded a piece of tubing to the frame mount for the early-style
mount to fit over and bolt to.
A LS-series wiring harness from a reputable company is
something you simply cannot avoid when working with these engines. All of
the hard work has been done for you; it is simply plug and play. It's also
mandatory that you send your computer out for reprogramming. It's advisable
that you use the same company you're getting the harness from. Shown is
the Painless Performance kit for '99-up LS-series engines.
Scott Leon of GM Performance sent us his version of the
same basic idea that he used for a '70 Chevelle. It's a chunk of billet
with a hole drilled for the mount bolt.
While advancements are being made every day by companies
like Street & Performance, it is recommended to find a pre-'03 engine
that has a cable-driven throttle body rather than a "drive-by-wire"
unit, or swap the throttle body for the earlier unit. A cable is easily
adaptable to the stock accelerator linkage.
Here is a daily-driven 5.3-liter in a '72 Chevy with thousands
of miles on the odometer and not a single problem to speak of. And there's
more power and torque on hand than any stock small-block.
|It's always best to have shop and assembly manuals on hand
to make sure your installation is correct and to make the project as easy
as possible. We recommend factory manuals, available at Greg's