Question: I have a '74 Chevy Nova with a full 'cage and fuel cell in the trunk (it was originally destined to be a circle track racer). But because I already have a circle track car, I want a somewhat unique 4x4. I plan to build it on a Blazer frame. I want to run it mostly on sandy/muddy trails. I want a 451 or 502 with multiport fuel injection.
I was wondering if it would be worth it to put a twin-turbo system on it or a big 8-71 blower. Which would be more cost-effective, and which is better for off-pavement use (strength and rigidity)? My concern is which setup will make better torque sooner. I know that I can change the pulleys on a blower, but what can I do to a turbo to change the rpm range? Also, I was reading a magazine and they mentioned a 10-71 blower-do you know anything about it and if it really exists?
My plan is to have about 40 inches of spinning rubber, and of course gears to match, but I am also wondering if I should get a TH400 or 700R4 tranny (unless you know of something better); either one would be built up, of course.
I am leaving for Fort Benning near Columbus, Georgia, for my Basic/AIT, Airborne, and Ranger school in January and won't be back until at least July. From then, I have to save money and find time to do this build. I plan on keeping you posted as to my progress (pics, notes, videos, and so on). This will be a trail-only rig, so legality is not a concern since it will be spending most of its time on tank trails and the like.
Answer: Before you go forward with this project, I figure that you must have a rich relative who is going to pay for all this-or that military pay has taken a big jump. An 8-71-style blower on a built big-block most likely will be in the neighborhood of $20,000 to $35,000. The Turbo 400s can be built up to about 600 hp but cost at least $2,500 with the torque converter. Axles will need to be custom-built Dana 60s, or better yet, Dana 70s or 80s, so count on another $15,000. It will take a lot of radiator, oil cooler, and transmission cooler to keep temperatures under control, so toss in a couple more thousand. Forty-inch tires on matching rims will cost about $600 to $1,000 each, depending on the tire/rim combination you use. You're going to need additional stopping power, so put several thousand away for brakes. Now we haven't even got to suspension and frame modifications yet, or body modifications needed for tire clearance. Want to rethink this project a bit and scale it down?
Question: I have a '94 Wrangler YJ that has a spring-over front and rear. Custom modifications were performed on the front for the steering and other required mods. A 4:1 transfer-case kit was installed as was a slip-yoke eliminator.
I currently have the heavy-duty six-leaf spring packs installed. The springs are approximately flat when parked. The rear does not appear to be lower than the front. The ride is fine with the heavy-duty springs and nitro shocks.
The problem is a vibration in my driveline at about 1,500 to 2,000 rpm in Second and Third gears. The vibration goes away in higher gears, but returns on uphill highway climbs. The gears have been changed to 4.10:1 and I am running 33x12.50R15 tires on 15x10 rims. The mechanic who did the work put shims under the springs to get the correct angle from the pumpkin to the slip-yoke. He thinks the vibrations are coming from the springs relaxing too much. I am thinking of installing some Firestone soft-ride air springs to bring the rear up some to correct the flat-out on the springs.
Answer: What is happening? The rear springs are flexing and turning the pinion upward when you accelerate or put added power to the driveline, such as when you're going up a hill. This change in pinion angle results in the U-joints at each end of the driveshaft rotating at different rates. Actually, the front half of the spring is flexing upward and the rear half downward. This is a pretty common problem with flat springs on a spring-over conversion. I am surprised that you don't experience wheelhop when climbing or accelerating hard when off-pavement.
I really don't like the idea of airbags. For one, it's something else to go wrong. Second, unless you run a lot of air to push the leaf springs into a considerable arch, they won't do much to help your problem. With additional arch, the back end will be considerably higher than the front, and your Jeep will look like a "stink bug" and the pinion angle will be wrong.
Some people have been able to stop or control this problem by a custom set of leaf springs that have a special loop around the spring eye, along with offsetting the spring's locating pin. The offset pin results in the front half of the spring being longer than the rear, which helps counteract spring wrap. This also will require new spring mounts. I believe Alcan ( www.alcanspring.com) has made some of these type springs. Another solution is some type of a center-mounted traction or antiwrap bar like the one that Sam's Off Road (www.samsoffroad.com) sells.