October 2006 4x4 Tech Questions - TechlinePosted in How To: Tech Qa on October 1, 2006 Comment (0)
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Question: I pulled an AMC 360 with a TH350 tranny out of a '72 Jeep Cherokee. I'm going to rebuild the 360, and put them both in my '80 Jeep CJ-7. Since the TH350 was made to go in a Jeep vehicle, will it need an adapter to mate up to the Dana 300 transfer case that's in the CJ?
Answer: To start with, the transmission you have is a TH400, not a 350, as Jeep only used the 400 version of the GM automatic transmission. In fact even the little V-6 used this transmission.
Yes, you will need an adapter to the Dana 300 transfer case. Novak has one under PN 134 (www.novak-adapt.com).
Just as a note for those who are contemplating this same swap using a '76-'79 Jeep TH400, the Novak people tell me that this Jeep TH400 is a bit different and takes a special adapter. These later transmissions featured a special tilted transmission-case casting. This adapter configuration is unique on the market in that it levels the adapter's base foot for square mounting on the rear isolator mount and crossmember. This is useful in that the adapter allows installation without clocking your transfer case downward, or having your transmission mount sit crooked. The identifying feature of different transmissions is that the earlier cases such as those used from (I believe) '69 to '75, used a special adapter ring between the engine block and the transmission.
Question: I own an '00 Cherokee and am installing a Borla exhaust-header to tailpipe. I was wondering what your views are on heat wrap on the headers to keep the heat away from the intake. I understand it voids most header warranties and was curious as to the cons of doing such.
Answer: Heat wrap works excellent on drag-race vehicles-not so much to keep heat away from the intake, but to maintain the heat in the headers. Hot air, as in exhaust gases, flows faster than cold air, and therefore exits faster. Sometimes, it's used where necessary to keep heat away from other components, or in the case of engines like your 4.0 six-cylinder where the intake and exhaust manifolds are on the same side, to keep heat away from the intake. Would it help performance? Yes, maybe a bit-but not so much that you would notice any by the seat of your pants.
Now for the bad about it: Harsh environments like those experienced off the highway, especially mud and water, will not only destroy the wrap, but worst of all can cause damage to the exhaust system under the wrap. Moisture will collect between the metal and the wrap in the form of condensation when the motor is shut off. Yes, stainless steel headers, like the Borlas, resist corrosion a lot better than painted steel, but it still will happen. Another problem-and perhaps the worst one-is that excessive heat can build up in the area of the wrap and cause the tubing to "burn out" in that area. Drag racers don't really have this problem as their run time only amounts to a few seconds, while on your vehicle the heat will be held in for perhaps hours at a time.
I really suggest that you forget the heat wrap. The Borla headers are a great choice. I have used them on three different Cherokees and found that they're an excellent product. They really allow the engine to come alive and not only make more horsepower but seem to allow the engine to pick up rpm a lot quicker.
Question: I have a '93 4x4 Dodge Dakota and I would like to put a 2-inch lift on it so that I can use it more while hunting and 'wheeling. I understand how to lift the rearend (by putting blocks in). I was wondering if I was to put blocks in the rear, could I raise the front of my pickup by tightening the torsion bars up, since there are no leaf springs on the front end of my pickup. Or is there another way of lifting the front without much overhaul?
Answer: Well, you could raise the front of your truck up by just cranking on the torsion bars, but I sure wouldn't advise it. Yes, at first thought, it seems like this is a low-cost way to gain some lift. The problem is that while gaining the lift, you lose downward wheel travel, which means that the wheel no longer wants to follow the trail properly and also results in a very harsh ride. It also puts more load on the torsion-bar mounts and could cause failure. The early Dakotas are really limited to aftermarket accessories, and lift kits are no exception. However, Trail Master makes a very nice 4-inch lift kit in the $1,700 price range.
Question: I have a '68 455 Olds motor I would like to install in a '73-'87 GM chassis with a TH350 transmission. The bolt pattern is obviously not the same, but yet I have read Readers' Rigs specs in the past that say they have one in their unit. I'd like to know what parts are involved, or if I have to fabricate something. Names and phone numbers of anyone that has done this in the past would be greatly appreciated. If there is no conversion to do this, I am selling the motor to someone who could use it.
Answer: A stock TH350 might not hold up to the torque of 455 cubic inches. You should consider a performance rebuild before doing the install. Better yet would be a TH400, but my guess is that you already have a 350 trans mated to a 205 transfer case.
You're on your own for motor mounts, but that shouldn't be much of a problem. My choice would be to use the factory block mounts and build some type of a stand-off on the frame. Yes, you will need an adapter to go from the Buick/Olds/Pontiac block pattern to the Chevy transmission pattern, and Jeg's High Performance (www.jegs.com) has just what you need (PN 555-60170).
Question: I own a '50 CJ-3A. It has a '67 Chevy 327 rated at 270 hp, a Borg-Warner T-18 transmission, and a Spicer Model 18 transfer case with a Warn overdrive attached. The adapter between the trans and transfer case is a '74 Jeep factory T-18 to Model 20.
As you know, the Model 18 has a passenger-side drop, both front and back. Is there a transfer case that has a center drop and can use the OD unit?
Answer: The overdrive is mounted where the PTO would be mounted. A special gear replaces the original main shaft gear and sends power into the overdrive unit and then back into the transfer case. The great thing about this is that it can be used in four-wheel drive, both high- and low-range, as well as in two-wheel drive.
There used to be a modified version of a Borg-Warner overdrive that was adapted to the Dana 20 transfer case, and then later on, Sierra Machine built a manual-shift overdrive unit for the 20. These were bolted to the transfer case at the rear output shaft, so naturally they were only usable in two-wheel drive.
If you want to keep your Warn overdrive, you will have to run with an offset rearend. When you think about this for a minute, it's not such a bad idea because now you know that if the front axle clears a rock, the rear will too.