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August 2010 Techline

Posted in How To: Tech Qa on August 1, 2010 Comment (0)
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August 2010 Techline

Where To Write
Address all correspondence to: Techline Four Wheeler, 831 S. Douglas St., El Segundo, CA 90245. You can also reach us by e-mail at fourwheelereditor@sorc.com; be sure to type the words "Tech Line" in the subject line. All submissions become the property of Four Wheeler, and we reserve the right to edit them for length, accuracy, and clarity. The editorial department also can be reached through the Web site at www.fourwheeler.com. Due to the volume of mail, electronic and otherwise, we cannot respond to every reader, but we do read everything.

What's That Noise?
Q I have a 1985 Jeep CJ-7 with the 258ci six-cylinder engine and Borg-Warner T-5 manual transmission. There is a loud "chatter" noise coming from the clutch at speeds over 55 mph, with the tach reading around 2,000 rpm, and only when gas is applied. It quiets down and goes away when you let off the gas. I have a Centerforce Stage 2 clutch that I installed 1,000 miles ago, which replaced the throwout bearing but not the pilot bearing. What would cause this noise?
Matthew Krzesniak
Chicago, IL

A I'm really not sure why the clutch should be making noise at highway speed and is (if I understand what you're saying) not making the noise at the same rpm and lower vehicle speeds. Are you sure it's coming from the clutch and not the transmission? The T-5 is noted for having some bearing problems that will cause noise when in Fourth or Fifth gear, but usually the noise is foreshadowed by difficult shifting. Perhaps you can give me a few more clues?

More Information on TBI Conversion
I wanted to comment on the question "Fuel Pump Mods for TBI Chevy V-8 Swap" (May '10). The reader wanted to swap a TBI 350 from a single-tank '90 Suburban into an '83 dual-tank truck. You mentioned that a reader might have another solution. Here's mine:

Basically, this reader is trying to make his '83 work as a TBI model like a factory TBI '87 regular-cab or an '87-to-'91 crew cab, so why not find one of these as a donor for a few parts? My experience is that many 1/2-tons, most 3/4-tons, and all 1-tons run factory dual tanks. All that is needed are two factory in-tank fuel pumps (and they will fit into the '83's factory tanks-just swap complete sending units), a factory fuel-tank transfer valve from a TBI truck (they look and mount identically to the one in the '83 but are different due to fuel pressure difference and additional wiring to the pumps), and the short piece of wiring that runs from the transfer valve to each electric fuel pump. The switch on the dash of the '83 that determines the left- or right-side tank should be the same.

The two in-tank factory electric fuel pumps and the transfer valve should be available at most parts stores if you just want to buy new parts. Just be sure to say it's for an '87. The short piece of wiring from the tank valve to the fuel pumps is the only part you really have to scavenge, and you could make it if you had to.
Justin Moffitt
Via the Internet

Thank you for providing another solution to the dual gas tank problem. I'm not quite sure why I didn't look into seeing if the TBI trucks had dual tanks and how they worked. Really appreciate it when readers help other readers out.

Wants Info on Early Land Cruisers
You gave me some pretty good information on my Chevy pickup some years back, and I am hoping you can help me out again. I am thinking about buying a Toyota Land Cruiser. You know, one of the classic ones from the '60s or early '70s. However, I don't know much about them. Could you enlighten me?
Tom Bown
Brownsville, TX

A I am not really into early Toyotas, so I don't have a lot to offer. I could have spent some time doing an Internet search for you, but then again, you could do the same thing. What I will do is tell you what I know just off the top of my head and from the few notes that I found in an old file. Perhaps that will be enough to get you started. I may be off a year or two on some of the dates, and I will probably hear back from some people telling me either more information or that I missed something.

The first Land Cruisers I ever saw were around 1961, but I understand that there were a few brought into the U.S. before that, perhaps 1960.

These early ones had a three-speed column shifter and a troublesome vacuum-shift transfer case. At the time, there were aftermarket conversion kits to a floor shifter for both. If memory serves me right, there were both offset and centered transfer-case rear outputs, but I can't remember the years. (Readers?) I think that the first couple of years they were imported into the U.S. they had a centered rear output. I do remember rumors that the '64-to-'69 transfer cases were prone to cracking. Oh, and that there were something like six different transfer cases used. The '86-'87 'cases are supposed to be the best, with a 2.26:1 low range.

The emergency brake was kept on the back of the transfer case until 1981, when it was moved to the rear brakes. Somewhere around 1974, they came out with a four-speed trans, but unlike the ones available outside of the U.S., it only had a 3.55:1 First gear and the transfer-case gearing was raised from a not-so-great 2.00:1 to an even less 1.90:1 low-range. I believe that the axle ratio was changed from a 4.11:1 to a 3.55:1 gear. There are special adapters available to swap in a GM truck four-speed. Maybe better yet is the Australian H55 five-speed, with a 4.80:1 First and a 0.85:1 overdrive Fifth, which is available from a couple of sources.

None ever came with power steering, but the good old standby-the GM Saginaw power steering box conversion-is what most people use.

Earlier bodies supposedly have heavier metal than the later ones, but I have no idea where the year break was.

The rear axle used a 91/4-inch ring gear with 10-spline axleshafts up to maybe '68-after that they went to 30-spline, both of which were about 1.30 inch in diameter. The early years had a 10-spline pinion shaft, and around 1979 Toyota went to a 27-spline and drive-flange setup. All were offset except the very early ones that I mentioned earlier. The front and rear differential units (I believe) were interchangeable.

In about 1968, they changed the front axle U-joint design from a ball-and-socket joint to a Birfield system. In 1976, disc brakes came out and I've been told that these can be swapped over to replace the old drums.

The first engine was almost a direct copy of the early Chevy six-cylinder. The early ones, labeled the F-motor, had about 125 horsepower. I think that there was a change in the head design about 1968. Burnt valves up to that time were pretty common. In about 1975, the F2 was introduced, the bore was increased, compression was raised, and the power went up a bit into the 135hp range.

Some people may dispute this, but I know for a fact that the distributor and starter were almost a direct swap from the early Chevy Six and that the Offenhauser dual-carburetor intake would bolt right on with some slight hole elongation. Unfortunately, I can't remember what year the vehicle was that I did the swap on.

As to aftermarket parts, there are still a lot of them available. I am sure that if you did a Google search on the Internet under the part or modification you were interested in, you could find just about anything you wanted.

Built 360 Gets Lousy Mileage
I would like to ask a professional about the mileage I am getting. What I have is a '90 Jeep Wrangler. I decided to buy a rusted-out '89 Grand Wagoneer as a donor vehicle. I rebuilt the 360 motor, the TF727 transmission, and the Dana 44 axles and put them all into my Wrangler. I knew the 360 was not known for its fuel economy, but I did think that 12-15 mpg was not asking too much. Currently, the still-new rebuild (600 miles on the ticker) is getting a solid 8 mpg (average). The guys at my local speed shop say that this is an acceptable mpg, but I want a second opinion.

I'll start with the details on the engine and work on down to the rubber. The 360 was relatively low mileage, but I had it bored 0.030 over. The same machine shop replaced the valves and installed new pistons on my old rods. When I asked them about the new compression ratio, they said that it was beyond them to say for fact, but that everything they did was to keep the compression relatively the same as stock. I installed a Comp Cam Xtreme Energy cam; this has intake duration of 256 degrees and 0.477-inch lift; exhaust is 268 degrees and 0.484-inch lift. A true double-roller timing set helps with the torque load. Outside, I used Edelbrock shorty headers that run two 2-inch pipes into one Flowmaster muffler with a 3-inch output. I installed an Edelbrock Air Gap manifold and topped that with a Holley 2-d Pro-Jection TBI. Spark is managed by a D.U.I. distributor, and I had a trusted mechanic set the timing. An electric fan also relieves some of the engine's responsibilities. You can see that the engine is rebuilt more than it is built up.

The TF727 was rebuilt to stock specification, and I added a B&M auxiliary cooler. I know that a three-speed is not the answer for fuel economy, but I just don't see many miles faster than 45 mph, and the budget didn't allow for a different tranny.

For the axles, I went with 4.88:1 gears and ARB lockers. The Grand Wagoneer had been a full-time four-wheel drive, but I kept my Wrangler's NP231 transfer case in the mix, so I installed Warn manual hubs in the front.

When I bought the Wrangler, it had a 3-inch body lift, and I installed a 4-inch leaf-spring lift. During the current build, I left the suspension as is, that includes keeping the spring-under design. If not for the tires, I would have actually lost some ground clearance due to the larger tubes of the Dana 44. For tires, I went with Interco IROK 36x13.5 radials. I have them inflated to 45 psi for pavement purposes.

As far as calculating my mileage is concerned, I always use the same gas station and usually the same pump. I can't swear that my odometer is accurate, but what I can say is that every time I pass one of those radar zones that post your speed, the sign is always exactly the same as my speedometer. Apparently, my tire and axle gear combo are right on target.

I know that the first response is that big tires, too few gears, and way too much open space under the vehicle are killing my mileage. And who could resist stomping on the gas pedal when you have a big V-8 in your stripped-down Jeep, but I have been trying to keep it civil since it hasn't been broken in fully.

I can say that the vehicle runs very well. It is harder to start than I would like, and it is grumpy until it comes up to operating temperatures, but after that, it idles smoothly, accelerates cleanly, and rumbles down the road like a champ. I have not found any fuel leaks, but it does smell of raw fuel, especially at start-up. I have been playing with the choke controls on the Holley, thinking that I was losing too much fuel during warm-up, but it seems to run best right where it is. While checking the specs of my cam to prepare this letter, I noticed a disclaimer saying that this cam needs 0.150-inch-longer pushrods. Could this be part of my problem?

Am I getting realistic mileage for my vehicle, or is there something that I can work at to improve that mileage?
Shawn Nichols
Bloomington, IN

I would not be very happy either with that mileage after spending a lot of money to build what sounds like a great engine for your Jeep. Yep, you're right-big tires, lots of dirty air under the vehicle, and lack of a higher gear are all contributing factors.

Let's start with the manifold first. Hopefully you bought the Performer Air Gap and not the RPM Air Gap manifold. If it's the latter, the match-up between it and the Holley Pro-Jection may not be good. In fact, the manifold may just be the problem as it was designed for a four-barrel carb and therefore you must be using some type of an adapter. You may just not be getting proper fuel distribution.

Have you done a check of each spark plug and viewed the burn pattern for a rich or lean condition between cylinders? Next is the camshaft. I doubt that the shorter pushrods are the problem, but the cam may not be lifting the valves to the full open position, and most likely the cam-to-valve-stem angle is a bit off and may just cause some sideways pressure on the valve stem, which will cause early valve guide wear. The cam you picked is pretty mild and one that I would have recommended, but-it just may be the influencing factor in at least part of the poor fuel mileage. I wanted to compare it with a stock cam but didn't have much luck, as the factory measures duration a bit different than the aftermarket cam companies do.

A couple of things that I would check before changing out the manifold (and I would suggest calling Edelbrock's technical services on this), would be that the timing is correct and that the distributor is advancing properly. This is where a good quality dial-back timing light really is a big help, as you can dial in the timing setting you would expect the distributor to be delivering at a given rpm. My guess is that you really don't want much over a maximum of 32 or so degrees of total timing at the rpm that equals the vehicle's normal highway speed.

Oh, and those IROK tires just may be part of the problem. They are a true 36 inches tall and very heavy. Combine them with a 10-inch-wide steel wheel, and the amount of weight you're trying to move is pretty staggering.

• Tech Letter Of The Month
Which Wheels to Go With?
I am restoring a '79 Ford F-250 4x4 with Dana 60s front and rear. I would like to go with 35-inch rubber on American Racing Outlaw II 16x10 wheels. My problem is that no one seems to be able to tell me if these wheels will fit. Most guys tell me to go with the 16x8s. I have found the right lug pattern, but am not sure of the offset. Please help if you can, as I'm going nuts with so many different answers.
Robert Moore
Loyalton, CA

Wheel width has a lot to do with personal choice, driving style, and what you expect the tire/wheel combination to do. There is also the clearance issue.

American Racing makes the Outlaw II in both a 16x10 and a 16x8 size, and both have the same backspacing, which is 4.5 inches. Your truck could have come with 16x6-, 16x6.75-, or 16.5x6.75-inch wheels. However, I was unable to locate the backspacing information for these. It shouldn't be too hard for you to figure out. Just lay a straight edge across the rim flange on the back side of the rim and measure down to the wheel mounting surface. My guess is that it will be somewhere around 3.75 inches, but I may be wrong.

Now as to the proper width: The narrower 8-inch wheel will cause the tire to bulge more and offer better rim protection. Depending on the sidewall design of the tire, you may experience more tire roll, especially at lower pressures, and perhaps a bit of improvement in ride quality. Most likely at higher air pressures, the narrow rim may cause the tire to "crown" somewhat and exhibit center tread wear. There may also be some tire contact due to the tire bulge with the frame under full turning lock. The wider 10-inch rim will put the center of the tire about one inch farther out from the frame, giving the truck a bit wider stance and most likely preventing frame contact on full turning lock. The ride will be slightly stiffer, as the tire's sidewalls will be straighter up and down. You may have some fender clearance issues when the tire is turned and the suspension compressed, but I don't think you will.

Bottom line: If it was my choice, I would go with the 10-inch wheel.

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