Tips To Upgrading Your Six-Powered Ride - Engine Swapping 101 - Valiant Effort: A Project Car Even We Can Afford
Sometimes An Engine That's Longer Isn't Quite As Good As One That's Wider
From the August, 2002 issue of Mopar Muscle
By Randy Bolig
Photography by Randy Bolig
With 170 cubic inches, it...
With 170 cubic inches, it was dependable, but a powerhouse it wasn't.
It was a simple idea. The '67 Valiant we introduced last month ran fine, but the reliable 170-inch Slant Six that was given residence between the front tires just wasn't what I had in mind. Sure, these engines can be built to produce some respectable numbers on the dyno, but not without some serious mods, and let's not even mention the difference in the sound. So, in this next installment of Project Valiant Effort, we investigated some things you may want to consider if giving your six-powered ride two more cylinders. There are different ways to accomplish this-the way the engine gets mounted, the suspension, and even cooling needs can be covered in a variety of ways. Hopefully, we can give beginners some information and perhaps add to the knowledge of the more experienced. In the end, we want to make this thing run well and keep it together long enough to make pass or two at the track.
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A friend told us he had a...
A friend told us he had a '71 360 he would sell. When we got to his house, he also had another 360 and an 8 3/4 rear from an A-Body he threw in with the deal. Not bad for 250 bucks, eh? A nice thing about buying a complete motor is that usually all the bracketry and pulleys you need are already on the motor. This saves expense and the time spent trying to find the miscellaneous items.
Ron thought the engine had...
Ron thought the engine had fairly low mileage, so a quick inspection of the plugs and bearing surfaces showed good indications. With high hopes, we cleaned and painted the engine and brackets and installed a spare Edelbrock Performer intake that came with it. We topped all this off with a Holley HP 650 carb and Crane 25 ohm wires. The HP series carb may cost a little more than a standard 650 but will stay with the engine longer during our upgrades.
To physically mount the V8...
To physically mount the V8 where the six was, either change the K-frame to a V8 unit or do what we did and get Schumacher Creative Services' swap kit. The kit came with the motor mounts, tranny mount, and all necessary hardware. We also got their new torque strap kit, which goes from a motor-mount bolt to a bracket that mounts to the K-frame.
The exhaust can be tackled...
The exhaust can be tackled by buying those quiet A-Body V8 manifolds or going the easy route like we did we did-headers. We chose Hedman Hedders with a 1 5/8-inch tube into a 3-inch collector. The Hedmans are coated inside and out, and for performance you can't beat a good set of headers: Hedman also sent us a crossover tube, which helps performance through a scavenging effect. Regardless, the six's skimpy exhaust wasn't going to cut it.
To mount the tranny to the...
To mount the tranny to the motor, the bellhousings are different. In the case of our Valiant, we didn't want a three-speed tranny for obvious reasons. So we bought a 23-spline 833 tranny from a friend for $200. Since we needed a bellhousing, another friend sold us a Lakewood safety bell for $40. It may be heavier than the factory unit, but keeping the flywheel from coming up through the floor like a buzz saw seemed kind of important. It pays to ask what your buddies have sitting in their garages while doing this type of stuff.
The six-cylinder engine uses...
The six-cylinder engine uses a longer throttle cable than the V8 unit and will need to be changed accordingly. You can find one at a swap meet, salvage yard, or through the street-rod aftermarket.
A lot of guys who drag race...
A lot of guys who drag race use the six-cylinder torsion bars because they react faster with the added weight of a V8. However, they don't corner at any real speed. If you plan to drive your car a lot, upgrade to a V8 bar to support the added weight under driving conditions such as potholes, roadwork, and the occasional Dukes of Hazzard imitation.
Swapping to a V8 also means...
Swapping to a V8 also means you need to address the cooling system. The standard six-cylinder radiator (right) was in rough shape, but the V8 requires more cooling anyhow. We contacted U.S. Radiator and got one of their V8 replacement units with the special "optima core" (left). Since the Valiant will serve double-duty and eventually receive even more performance,we needed a radiator to handle the task both now and down the road. In essence, buying it once is better that having to buy another one later.
Our car had the small 7 1/4...
Our car had the small 7 1/4 rear, by no means able to handle what we were about to throw at it. Like I said before, we got lucky with an 8 3/4 spanner along with our engine, and after we install our built-742 case differential, it will be fine. The price of upgrading to an 8 3/4 (especially in an A-Body) is climbing, especially if you want the larger 4 1/2-inch bolt pattern axles, so plan accordingly. While you can compromise with the 8 1/4 under some circumstances, the 8 3/4 remains the rear of choice for most non-Hemi street cars.
When going to a V8, there...
When going to a V8, there will be more stress on the driveshaft. If you plan to really launch your car hard, especially with a four-speed, we strongly recommend getting the sturdier V8 driveshaft; you can either have one made or locate one from a V8 car. Under normal transportation-only type driving, the smaller one would probably work fine, but who of us does that? Also keep in mind that Mopar offered two different size universal joints: the 7260 is the smaller unit, while the 7290 is larger and more durable; these need to be strong. Finally, if you are using an automatic with a fairly stock converter; this will be a little more forgiving since it's a "fluid coupling system" instead of a direct gear. The verdict: Better safe then sorry; upgrade to the stronger styles as soon as you can.
Another often-overlooked area...
Another often-overlooked area is the wiring. The Slant Six starter is on the drivers' side near the top of the motor. On a V8, it's underneath. Tip: Some wiring modifications, like lengthening and rerouting, will be required; have the tools or a harness to do this.
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Schumacher Creative Services