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Swing N Sting 1971 Dart engine rebuild begins

The Swing ’n Sting Engine 318 Program Goes Into High Gear

John and Geoff Stunkard - August 01, 2011 09:00 AM

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The Whiplash Muscle Car cam and valve gear from Hughes Engines is made for fairly low rpm, low compression engines.

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The cam comes with a lot of additional details for safe installation. We will be paying attention and you should too.

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The new rocker arms are a work of art. They are offered in a very nice 1.65 ratio to allow even greater performance.

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Additionally, Hughes has the guide plates and studs for our new heads. They took the heads and added their springs and retainers to match the cam.

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Hughes springs with inner damper and their retainer finished off the valvetrain parts.

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These are EQ’s new heads, which are based on the later Magnum designs but have addressed design issues.

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Note the quench area in the combustion chamber. It measures at 62cc and will give us a little more compression with the stock pistons.

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The intake port is mildly restricted by the pushrod layout, but will not have much effect on the low-rpm engine build we are doing.

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The intake port is mildly restricted by the pushrod layout, but will not have much effect on the low-rpm engine build we are doing.

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The exhaust port is much better than anything from the old days. Our tti headers will bolt right up to this. Note that Hughes stamped our name right on the heads to prevent any confusion at the shop.

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Here is the new PRW water pump. It will be “styling” on the front of the motor, but it’s more than beauty.

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Check out the CNC-cut impeller with a roller-bearing rotation. It’s good for lots of coolant at speed.

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The rest of our Mancini parts were on the way; this is the new timing chain set and Magnum valve cover gaskets.

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There are a lot of options available when you decide to begin building horsepower, but everyone will tell you it’s the overall combination that makes a difference. We have already made several changes to the Swing ’n Sting Dart, but it was now going to be important that we piece together what will work.

The objective is to try and get the car into the 13-second range, even without changing the rear gear set. We are hoping that we can do that with our upcoming engine changes. For this, we relied on Hughes Engines, Mancini Racing, EngineQuest and PRW and what will be the most serious hands-on work we have done yet.

We had thought about going with a 360 swap, but waved it off for a couple of reasons. The first was most important – cost. We decided that we would stay with our 318 for now, knowing that virtually everything we had acquired to this point could be bolted up to an LA-series 360 at a later date. We knew this engine was running well and hoped that we didn’t find any problems once we took the heads and pan off of it. Also, since this was my first “big job” inside the engine, the 318 will be a good “test project” for me. With the “Street Fights” at Bristol Dragway getting underway already, I am excited to do this.

So here is a quick look at the parts that will go on this time, as I imagine I will have some interesting stories to tell after we actually do the work!

 

HUGHES ENGINES

Cam & Valvetrain

We stopped by and saw Dave Hughes and his shop in Washington, Illinois, while we were traveling to Mopars in the Park last year. Dave has been building specialty Mopar engines and parts since 1969. After hearing about our plan, he told us he had a good cam for the Dart, his Whiplash Series flat tappet hydraulic (HMC1326AL-9). This makes use of a couple of things that Dave has done. Most importantly for Mopar owners, Dave has these cams ground with true .904 lobe dimensions. They are created so the larger Mopar-type lifter rides on the cam face properly. By using the Mopar diameter, a Whiplash cam is able to be created with a faster rate-of-lift (the amount of lift when measured to crankshaft location). This ramp speed allows Hughes to design fast, large lift rates into street cams.

If you are looking for a top-end, big rpm race cam, this might not be a great choice (Hughes’ Max Velocity series would be the way to go there). For our low-compression, street-based 318, this one is perfect. The lift numbers look radical – .517 intake, .552 exhaust – but due to the ramp design and duration at .050-inch (213° intake / 226° exhaust), they are made to maximize cylinder pressures even with our stock compression ratio. Coupled with our street/strip Dynamic converter, this thing should scream throughout the torque range up to about 5,300 rpm, which is about all our mini-mill is good for unless we begin doing some serious bottom-end rebuilding.

Dave also matched us up with all the right valvetrain stuff to complement this cam – lifters (HUG5001), pushrods (HUG5250), and Hughes’ exclusive 1.65 ratio rocker arms (HUG1550). These are actually going to increase our lift a little more, and we will be testing them on the street with the new heads and cam. We also forwarded the new heads out to Hughes for springs and retainers. While Hughes is well-known for porting changes, we did not touch the ports or pockets because we really wanted a good baseline on them as cast. Hughes did provide a high-flow racing valve job.

The valvetrain is a critical part of an engine build – it’s usually win or lose, rarely draw. Relying on a knowledgeable engine builder like Hughes Engines, who focus on Mopar products, was one of the smartest things we could have done. You probably won’t find Hughes parts on the discount rack. It is always money well spent with these guys, who know what they are doing.

 

Hughes Engines, Inc

(309) 745-9558

www.hughesengines.com

Engine Quest

LA-intake-drilled Magnum heads

We ran into the guys from AAEQ/Engine Quest at SEMA thanks to our friend Leslie Allen of the Marx Group. They had a set of iron heads that are sort of the best of both worlds. These units are cast in Australia using modern technology, so they are actually cleaner right from the foundry than any muscle car-era factory casting. The heads (CH318B) are basically a 1992 to 2004 Chrysler 318/360 design that has been machined for a pre-1990 LA-style intake pattern, but still uses all Magnum rocker parts. Port-wise, there is a hefty 172cc intake runner and a tight 62cc combustion chamber. We are figuring that will bump our compression up about a point with the Fel-pro gaskets. They also offer this head design for the Magnum bolt pattern. Moreover, EQ has redesigned the water passages, thickened the deck, and added hardened seats for the spit they call gas these days.

The nicest thing about the EQ heads is that they are economical if you are on a budget. They allow you to take advantage of the design characteristics of the Magnum air flow improvements. We are hopeful that, coupled with the cam specs, this will be a prefect street car layout.

 

Engine Quest

(800) 426-8771

www.enginequest.com

PRW High Volume Water Pump

The last piece of the mixed parts deal was a new water pump. PRW has one for the A-series Mopar (1431810). Though our BeCool radiator conversion had resulted in dual electric fans on the car, we did not need to go to an electric water pump. PRW had just the right stuff, since the pump has been designed with flow in mind, and the CNC-machined impeller is capable of moving 35 gallons a minute at 4,000 rpm. It is also able to minimize cavitation. Engineered for extreme use, this is no OEM ’60s technology – steel hubs and shielded-seal roller ball bearings, O-ring sealed back plate, and pressure injected alloy body. Assembled to aircraft quality tolerances, this may the best replacement street/strip mechanical pump on the market.

 

PRW Online Store

(866) 412-9630

www.prwonlinestore.com

 

Mancini Racing

All the other stuff…

Did you know that Mancini will match any advertised price from the other big-box retailers? Since 1971, these guys have been the go-to guys for the hardcore Mopar enthusiast, and they carry a huge array of parts and pieces. As we finished this up on deadline, the Detroit crew was shipping us the final pieces of our puzzle – the gasket rebuild set for the 318 (FEL260-115), a new Melling oil pump (MELM72), and a set of standard bearings (M77MS1344P-mains, M77CB481P-rods), so they are not pictured here. We are really, really hoping that our fairly low-mileage engine will be able to get by with a bearing swap; we won’t know until it’s taken apart, and then we will call for rings. We have to wait on those as we don’t know if a clean-up hone will be enough, or if we will need to check on pistons as well.

Mancini was also our go-to source for a timing chain outfit (MRE-262) and the Magnum-type valve cover gaskets (OEM Mopar 53006695) that the new heads require.

 

Mancini Racing

(800) 843-2821

www.manciniracing.com

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