Cross Pollination
I'm currently restoring a '70 Chevy C-10. Once I get done with the transmission, I want to rebuild my frontend and drop it 2 to 3 inches. A friend of mine gave me a complete frontend off a '74 Chevy van, right down to the rotors. He says that this frontend will match up perfectly, but I will have to use '74 tie-rod ends. Do you know if this '74 frontend will work on my '70 pickup?
Dave Collins, via e-mail
We've heard that the van stuff bolts, but we haven't done it ourselves to know for sure. So if anyone has done this conversion, please drop us a line and let us know the outcome. Don't lose hope, though; there might be a way to use most of the stuff from the van clip. Early Classic Enterprises [5843 E. Clinton Ave., Fresno CA 93727, (888) 777-0395, (www.earlyclassic.com] makes spindles that are machined to accept your original tie rods and ball joints. So you can throw these spindles on and mount the disc brakes components from the van on that. The spindles will lower the truck 2-1/2 inches without having to stack up a bunch of alignment shims on the control arms to adjust the camber.
Compression Questions
I'm a devoted subscriber to your magazine and am writing to you for your expertise regarding a Chevy big-block 396 engine. I bought this engine really cheap from a friend of a friend of a friend. I've done some research on the engine and have figured out that the engine is a 325hp 396 big-block with a 10.25:1 compression (L-35 engine code). It originally came in the '66-'68 Impalas. It appears to be completely stock from carburetor to oil pan. The Rochester Quadrajet carb numbers match those mated to these engines, as do the cylinder-head casting numbers.
So here's the deal. I have a '75 Chevy Scottsdale longbed that I've been working on for years. I live in California and found out a few years back that California was planning on changing the smog laws to a rolling smog-exempt rule. It was for that reason that I originally bought the 396. That law change never came to fruition, and now I've put off plans to install the 396 in my Chevy truck until it is smog-legal to do so. However, as this may never happen, I may have to purchase a pre-'73 truck to put the engine in.
My concern is the compression ratio. I've been researching (mostly on the Internet) about how pump gas and compression ratio affect performance. With current gas prices about $2 a gallon for 87 octane, I don't plan on feeding the 396 big-block the premium 92-octane fuel it requires. It's my understanding that a 10:1 compression is too high to run on 87-octane fuel. I don't plan on doing any mods to the big-block other than a rebuild. The stock components will be rebuilt and reused (the heads, short block, and so on) unless they're damaged, in which case they will be replaced with stock components. I know that I've read of vehicles in your magazine using 10:1 and even 11:1 compression ratios. I even read something about the ZZ502 motor having a compression ratio of 10:1.
My question is simple: Can a stock late-'60s big-block engine (with a10.25:1 compression ratio) run on today's 87-octane pump fuel with no modifications? I originally thought it would be great to swap in that 396 (largely for more power) and have the benefits of the four-speed 700R4 in addition to my current 3.73 gears in the rear differential. However, I'm having second thoughts. Please help me understand why there are so may different opinions in this matter. Thank you in advance for your time and attention to this matter, and I sincerely hope that you will be able to educate me as you have done in the past.
Robert Martinez, Grover Beach, California.
Will an engine with a 10:1 compression run on pump gas? Yes. Will it run on 87-octane pump gas? No. Will it run on 92-octane pump gas? Yes. Looks like you'll have to pay to play if you install the big-block in any kind of truck. But before you get your heart set on using this engine, there are a few obstacles you need to consider.
From 1965 to 1968, gas was leaded and had higher octane ratings. The engines of that era were not designed to run on today's unleaded MTBE-infected fuel. Running that motor on today's fuel will slowly eat away the exhaust valve seat. This will tighten the exhaust valve lash as the valve sinks into the head, and will eventually cause major engine damage. Hardened seats will need to be put in the heads and a valve job will be needed.
As far as running 87 octane, you could simply change the cam to bleed off some of the cylinder pressure from the compression. The consequence is that the cam change will compromise a little torque from the increased duration that would be needed. If you're stuck on using 87 octane, it would be better to drop to a 9.5:1 compression. The '95-'98 H.O. 396 head had a 96.4cc or 106.9cc combustion chamber. You may want to think about reducing the compression with new pistons or just bolt on a set of 427 heads that have a 114.8cc to 116cc combustion chamber; that will reduce the compression to about 9.5:1. This will eliminate your need to go to a wacky cam and save the torque that is so essential in a truck.
We understand you want to keep the engine stock, but unless you're an engine collector, or you're going to put the engine back into an Impala of the same era, it's not worth anything more than a junkyard engine. You may as well change it up to the passenger car-designed engine to fit your combination. You mentioned the price of gas; point well taken. There is no doubt that a big-block drinks the fuel pretty fast, so if that is a major factor, you may as well spend the money building a small-block. Also, the 700R4 won't last long behind the big-block, and if you don't overdo it with the small-block, it will live quite a while. Plus, the money you would save from not having to transplant a car engine into a truck would allow you to beef up the tranny to match the small-block.
Lifted Vs. Lower
Recently, you asked the question: lifted or lowered? Realistically, the answer should depend on where you live. If you live in Texas or California, you have mild weather and no snow, so driving a slammed truck is probably still practical. But if you live in South Dakota or Minnesota, there is plenty of snow and mud, so having a lifted truck would be more practical and having four-wheel-drive even smarter. Personally, my preference is a slammed truck rolling some 20s that has airbags and can sit flat on the ground. Also, are you guys looking for another photographer? If not, can I get a shirt or sticker or something so I can tell all my friends I am?
Clint Rainford, Huron, South Dakota
Regionality does play a big part on how you build your truck or whether you build a slammed 4x2 or lifted 4x4. Yet we've seen some killer slammed trucks come from snow country and wild lifted 4x4s in the flat and sunny country of Texas. A lot of it comes down to personal tastes and wants versus practicality. Thanks for giving us your opinion. And no, we won't send you a shirt or sticker so you can claim to be a photographer for Sport Truck. Nice try.
V-6 Throttle Body Upgrade?
I have a '97 GMC 1500 extended-cab pickup fitted with the 4.3L V-6. My question is, are there larger-diameter throttle bodies available for this engine, and if so, how would it affect its performance?
Sgt. Ovie Wayne Mulkey, 15th SOS / DOXP
If you figure an engine is nothing more than an air pump, then improving its efficiency by getting more air in and more air out is a proven way to make power. We've been preaching this philosophy for years and have a pretty good track record in terms of results. While individual parts by themselves work OK, it's usually a combination of things that makes a real difference. You neglected to mention any other modifications to the engine. We would recommend, at the very minimum, a good after-cat exhaust system and air intake. At this point, a larger throttle body would come into play. Morse Machine of Orange, California, smooth-bores the stock units to a larger diameter. A new, larger elliptical-shaped throttle plate is put in for more airflow. Contact the company at: RV Morse Machine, 330 N. Elm St., Orange, CA 92868, (714) 272-9058, rvm@rvmorsemachine.com
Plug Problems
I need some good advice. I wanted to install a set of Bosch Platinum +4 plugs in my '02 5.9L Dodge Ram along with a set of performance spark plug wires. However, one of the Dodge Boys (a local Dodge dealer technician) told me this would be ill-advised and that my check engine light would come on. He told me to get my money back and to buy Champion plugs instead. I have 27,000 miles on my truck and was also told that I should wait until I get to 30,000 before I change anything. I have read and heard so much about these plugs and I need to know what's the deal on the advice from this technician. Was he being truthful with me? Thanks guys and I love your magazine.
Ace180, via e-mail
In answer to your questions, we went right to the source at Bosch. According to the folks at Bosch, you're getting bad information from your technician. Bosch Platinum +4 plugs will not cause any problems whatsoever in your engine and very likely provide a slight increase in power, economy, and longevity due to the unique surface-air-gap design, pure platinum center electrode, and four ground electrodes. "Many people are not aware that at Bosch we actually test our spark plugs in every application listed in our catalog" said Matthew Hallis from Bosch. "This testing allows us to obtain application-specific data on every vehicle for which we make a recommendation. Our engineering work with automakers also helps ensure that our plugs provide optimum performance, which is why Bosch spark plugs are original equipment on many domestic models, including, for example, the new Chrysler Crossfire and Cadillac CTS. The gap is fixed on Platinum +4 plugs; no adjustment is necessary or possible. We suggest torquing your Platinum +4 spark plugs to the factory spec, which is 41 NM (30 lb-ft). No antiseize compound is necessary since our threads are nickel-coated to avoid corrosion and binding in the cylinder head." There you have it.