Introduction

Twenty three years ago, when I did my first V-8 conversion, information was scarce and aftermarket support hard to come by. The information that was usually there was trouble than it was help. Engine swaps were a kind of hit and miss adventure. Today there is a plethora of parts and info available on the market, some good and some bad. To date I’ve completed over 20 V-8 conversions in ‘40's, ‘55's and ‘60's, with nearly every conceivable GM tranny-motor combo.  I was involved with the build up and of both Tracy Jordan and Don Robbins ARCA Land Cruisers from 1998 to 2001, including acting as the spotter for Don during those years. Many of the parts I have brought to the market over the past 13 years as Renegade Fabrication and now MAF Manufacturing had their beginnings in the competitions. Items like the U-Bolt flip kits were bourne of necessity to bring the added edge that let us finish 2001 with a second overall on the year. Now, I would like to share some of my experience with those of you wanting to pursue that Holy Grail we call the perfect Land Cruiser, in a series of articles that will appear on this web site, the  following article to be the first.

V-8  Conversion Options: Pros and Cons
By Dave Gore

This article addresses a variety of options available ,their pros and cons and  problems you will need to address when planning and executing a successful V-8 swap.  Although not the only option , I will focus primarily on the small block Chevy as this is the most common swap and the option with the most aftermarket support.

Motor Placement:

The best advice I can give concerning motor placement is to put performance before convenience. In other words place the motor for optimum cooling.  Position the center of the fan as close to the center of the radiator as possible without sacrificing room for the air cleaner. Remember  to plan for any trans coolers or air conditioning components if applicable. Generally, if the motor is in this position you will also gain the best access for engine maintenance ( spark plugs, starter, bell housing, distributor, etc.) and you will have the necessary clearance between the front differential and oil pan for full suspension travel.

Transmission and Transfer Case Selection:

Choosing between  a standard and automatic transmission has always been a subject of debate.  Some hardcore off-roaders still prefer a standard with a deep "granny"  first gear because of the relatively low cost of attaining extremely low gearing.  With an automatic low gearing must be attained through either axle or transfer case gearing, the latter of which being more desirable because you can gain off road (low range) capability without sacrificing highway manners.  However, an automatic with numerically identical gearing will out perform a standard in all situations, on and off road, except the dead battery bumpstart situation. My opinion is that an overall gear ratio of 60:1 with a standard transmission would put you in the competitive bracket, while 40:1 with an automatic would be a benchmark point. But don't let that stop you from going 100:1 if you can. Slower going means more control and longer lasting parts.

Pros and Cons:

Standard transmission

Pros

* Wide variety of gear selections
* Shorter overall drivetrain package allowing flexibility with motor placement, less driveshaft problems
* Easy to bumpstart when battery dies or on a downhill

Cons

* Costly rebuild
* Requires deeper gearing than an auto for comparable off-road performance
* Clutch required

Popular Swaps

SM420.  This tranny has a  bit over a 7:1 first gear making it a popular choice for the avid off roader. Mating this tranny to a small block requires a stock pre 1968 bell housing and stock clutch components from a truck of the same era. An adapter to the transfer case will be required.

Because this transmission is long out of production parts are more difficult or sometimes impossible to attain, so inspect before you buy.

SM465 - This tranny is the chronological replacement for the SM420. manufactured into the 1980's these tranny's are more common and replacement parts more readily available. First gear is marginally higher but not an issue. Again, clutch and bell housing are stock GM components applicable to the stock arrangement and will require an adapter to the transfer case.  These two trannies are an inexpensive way  to achieve superiority off road.

NV4500 - This trans is a more modern unit. It appeared in early to mid nineties Dodge and Chevy  trucks. First gear is most commonly  5.6:1 qualifying it as a "granny" gear transmission but noticeably higher than the 420 or 465. What makes this tranny desirable is it's incorporation of a fifth gear overdrive.  Because this transmission was produced with many input and output configurations I suggest those of you interested in this conversion give Advance Adapters a call . They have an extremely helpful and knowledgeable staff that will explain all the options and what to look        for.  This conversion will be noticeably more expensive because both the adapter and the tranny have higher initial costs.


Stock 3 Speed  -  This is the least desirable choice for a couple reasons. The extremely high first gear ratio is poorly matched to the powerband of a V-8 resulting in a lot of rough terrain clutch slippage and stalling in the rocks. Not designed for high horsepower the longevity of this unit will be compromised.  It's only plus is cost. Bell housing adapters are cheap and no transfer adapter is required.

Stock 4 Speed  - A synchronized first gear and a more usuable gear selection make this slightly better than the three speed, however, the tranny is still on the fragile side for a V-8.  No transfer adapter is needed but a bellhousing adapter is required.  A non-U.S.A. 4 speed is available with a 34% lower first gear, making it a considerably more useful gearbox.

Automatic transmissions

Pros:

* Drivability
* Elimination of clutch
* Superior traction control
* Ease of hillside starts
* Simplicity of shift linkage (cable control)
* Repair & rebuild costs

Cons:

* Overall length
* Lack of available gear selections
* Requires transfer case gear work to achieve competitive overall off-road performance

Because of the torque multiplication effect of the torque converter, the automatic transmission can  perform well with higher overall gear ratios than the standard. An automatic in a vehicle with an overall gear ratio of 40:1 will perform better than the same vehicle with a 60:1 ratio and

A standard.   A 40:1 overall ratio would be what I would consider to be a minimum overall ratio for serious off roading. Because of the overall length of the automatic, rear driveshaft length is a more difficult issue to address than with the standard. Also tranny pan clearance may need attention, depending on the type of trans, overall lift, etc. This usually involves clearance on the corner of the pan near the front t-case yoke.

TH350, TH400  Both of these units are very common Chevy automatics. The 350 being the most common used in both cars and trucks up to 3/4 ton. This is perhaps the most common U.S. made automatic ever produced. Very cheap to maintain and rebuild and tons of aftermarket support.

The 400 is it's beefier big brother, used primarily behind big blocks or in one ton trucks.
It was designed to handle gobs of horses but unfortunately gained some mass in the process.
Overall  it's a few inches longer, eating up critical rear driveshaft room.
Both have about a 2.5:1 first gear making it more critical to play with t-case or diff ratios.

TH700R or 4-60LE  Virtually the same tranny , the latter being electronically shifted, these are overdrive units giving you that oh so nice highway performance. Even better, they have a 3.07:1 first gear. That's twenty percent lower than the 350 or 400. Because of the overall length,  I recommended relocating the rear axle back at least two inches with either the 400 or 700. This allows a longer rear drive shaft which will enable more wheel travel. Other side benefits of a longer wheel base are high speed stability, increased climbing performance and more stable descents.

Some common  methods of relocating the rear axle :

*re-drilling the spring perches ( good for up to 1 1/2")
*Have the rear main leaf remanufactured with the locating pin moved back
* reverse the shackle hanger and move back the front perch accordingly 

Transfer Case Options

Because of the offset axles found in the land cruiser it is easiest to stick with Land Cruiser transfer case for rear driveshaft alignment. Fj40 owners can upgrade to the FJ60 t-case realizing a 100% strength improvement.  This should be considered before buying adapters  because the adapter to the '40 case will not  interchange with the '60 case.  Aftermarket 3:1 gears are presently available for the '60 case  further enhancing the desirability of this unit.

 A replacement '40 case is said to be available in the fall of 2003 with a reported 4:1 low range and stronger case. I have not yet seen this or tested this item so I am unable to express an opinion at this time.

Summary

In conclusion, with so many choices and none significantly more costly than the other, before you spend your money twice, sit down and decide what you really want your truck to do and where you want to take it. There is nothing more disheartening than spending  $10,000 (or more) and 200 hrs of your time only to be left disappointed. Spend the extra money and time to get exactly what you want or you’ll grow tired of your truck quickly and it will spend most it’s life garaged. Or worse, you’ll sell it in disgust and buy a J**P. In which case you’ll be forced to change your identity out of shame,  move to a neighborhood of lesser standards, and buy a large trailer, to tow behind you on all trail runs, filled with the spare parts needed to get home. Also, your spouse, boyfriend , girlfriend, children and pets will leave you for a cruiser owner.