Dart Iron Eagle Cylinder Heads Install - Minimal Assembly Required!
Dart's Latest 372CI SHP Short-Block: Tested
From the May, 2009 issue of Chevy High Performance
By Sean Haggai
Photography by Sean Haggai
There are a number of benefits associated with building an engine from scratch. Not only do you get the enjoyment of bolting the thing together yourself, but a certain amount of pride goes along with it as well. You can say with the upmost confidence, "I did it." However, time seems to be scarcer than before and things can quickly turn south if you aren't careful. Wrong measurements can quickly send your once simple small-block build spiraling out of control with one-off custom components that can't be returned. Yes, this can happen to any engine builder-even the seasoned pros. What's worse is that it could push your build onto the back burner for a while.
We like to keep those incidents to a minimum. Besides, if all you're waiting on is an engine to throw into your weekend brawler or street car, why not choose something that's already been developed for you? Thrown-together engine kits sporting various odds and ends just won't cut it with the off-hand knowledge that today's enthusiasts hold and share on Internet forums.
What are your options? In this case, we'll give it to you in one word: Dart. Dart now offers a new line of Special High Performance (SHP) short-blocks that can be had without having to empty your pockets. If you're not familiar with the line, every block is precision-machined with features like Siamese bores, has ductile iron four-bolt mains and a priority oil main system, and is rated to safely handle up to 600 hp.
That's right, Dart has done all the hard work for you. Just top it off with a set of cylinder heads and a manifold, and you're good to go. It's for the guy that can't or doesn't necessarily want to measure for correct rods or check for adequate crankshaft thrust. Instead, this is for the guy who is willing to torque a set of heads and top it off with a manifold. Better yet, with Dart backing your new bullet, you get the security of knowing that it's going to bolt together without fail and you don't have to deal with the headaches normally associated with fitment.
These ready-to go-short-block assemblies are offered in your choice 372ci or 400ci and come with a number of internally balanced configurations to fit your needs, including your choice of a cast steel or forged crankshaft, 4340 I-beam rods with 3/8-inch cap screws, and hypereutectic flat-top pistons with optional forged units for higher horsepower applications.
For our testing, we opted for the entry-level 372ci short-block with the cast steel crank and hypereutectic pistons, and we complimented it with Dart's cast-iron 180cc heads and dual-plane manifold top-end package. If you're wondering what it took to prep this jewel for the dyno, let's just say that aside from removing it from the crate, the laborious half day (if you can call it that) consisted of fogging the SHP block with black high-temperature paint, installing the camshaft and lifters, and bolting on the induction. The results? Nope, you have to read on to find out!
What We Did
Topped off our Dart SHP short-block with its very own top-end kit and ran the mill on the dyno for the numbers to back it up.
Can't exactly put a complete short-block together? No worry-Dart has you covered.
Shortblock starting at $3,100.
Total build $6,926.
Top side, with bores at 4.125...
Top side, with bores at 4.125 inches and deck height at 9.025 inches, our build started off with low compression flat-top hypereutectic pistons with valve reliefs. Later when we added the Dart top-end kit, the 180cc Iron Eagle cylinder heads with 64cc chambers netted a 9.9:1 compression ratio.
Dart makes sure each SHP short-block...
Dart makes sure each SHP short-block assembly is fit and finished. Here a chamfered edge is present along the deck, and each head bolt hole is also chamfered. There are no sharp edges, and even the castings marks on the outside of the block are ground down.
Dart spent its time to ensure...
Dart spent its time to ensure that each oil galley is drilled, tapped, and plugged with a pipe fitting-no press-lock oil galley plugs here.
Charts are references to Breathing Better Caption.
|Dart 23-degree Iron Eagle Cylinder Head |
|Combustion chamber ||64 cc |
|Intake port volume ||180 cc |
|Exhaust port volume ||77 cc |
|Intake/Exhuast valve ||2.02/1.60 inches |
|Valve springs (dual) ||1.437 inches in diameter |
|FLOW FIGURES |
|LIFT ||INTAKE ||EXHAUST |
|0.200 ||139 ||114 |
|0.300 ||193 ||145 |
|0.400 ||231 ||164 |
|0.500 ||249 ||172 |
|0.550 ||253 ||173 |
Breathing Better Up top we...
Up top we utilized a Dart top-end package. At just $1,600 this kit was a no-brainer and comes complete with head and intake gaskets, only requiring a set of head bolts.
At the front of the block,...
At the front of the block, each assembly comes with recessed front oil galley pipe plugs. This is to make sure the timing chain and gear do not wear into each other. These kits also come with coated cam bearings.
At the foundation of the beast...
At the foundation of the beast are four-bolt mains. You'll notice that main caps No. 2 through No. 4 are splayed for better clamping force. The rotating assembly features a cast steel 3.480-inch crankshaft and forged 4340 I-beam rods with 3/8-inch cap screws. Clevite bearings reside throughout the short-block, with Hastings Moly rings surrounding each piston.
Our 'stick of choice was a...
Our 'stick of choice was a Comp Cams hydraulic flat-tappet featuring 230/236 intake/exhaust duration at 0.050 with lift numbers at 0.490/0.490 intake/exhaust on a 110-degree lobe separation.
We buttoned up the front with...
We buttoned up the front with a Comp Cams double-roller timing chain and gearset. We also used a bit of Loctite on the front cam bolts and finally torqued them down to 28 ft-lb.
While it isn't required, we...
While it isn't required, we used a Comp two-piece timing cover to facilitate future testing. This will make cam swaps easier since the front plate is detachable and we won't disrupt the front oil pan seal. Before installing the cover, we placed the gasket on the base plate and added silicone on top of the plate.
Next, we placed our Fel-pro...
Next, we placed our Fel-pro head gaskets (supplied with Dart top-end kit) and set the Dart Iron Eagle heads onto each bank. Using some Moly-lube on the head bolts, we dropped in each bolt and torque them down to 70 ft-lb in a clockwise manner, starting at the center bolt.
After determining that we...
After determining that we would need a 7.800-inch pushrod to complement our Comp Gold 1.5:1 roller rockers we could begin to install each one. Westech's Steve Brul locked each rocker down and lashed it to 0.16/0.18-inch intake/exhaust cold.
Dart SHP 372 1. With minimal...
Dart SHP 372
1. With minimal jet changes, the Street Avenger 770 performed flawlessly. It's a steal, too, at $449.
2. To expel the exhaust, we strapped on a set of 13/4-inch diameter hooker headers with 18-inch collectors.
3. The Comp two-piece timing cover allows for easy cam swaps. Inside sits a Comp double-roller timing chain, gears, and a 230/236 Comp hydraulic flat-tappet cam.
4. Dart supplies everything in its top-end kit, including its dual-plane manifold, which helps to produces great bottom-end torque for everyday drivers.
5. Our Dart 180cc Iron Eagle heads are a bargain. They come fully assembled with springs (we ordered dual springs), head gaskets, and head bolts.
Since this motor is destined...
Since this motor is destined for a third-gen Camaro, we tracked down an F-body-specific Milodon oil pan. We first spun the assembly over to test-fit the Milodon oil pump. Next we set the pump in a vise and press-fit the oil pick-up. We dropped in the pump shaft and bolted the pump onto the rear main cap. Then we set the gasket and front/rear seals and set the Milodon pan on top. We locked it all down using a set of ARP oil pan bolts.
To feed the fire, we went...
To feed the fire, we went with Holley's newest 770-cfm Street Avenger carburetor with an electric choke and mechanical secondaries.
Our Dart 372 performed flawlessly...
Our Dart 372 performed flawlessly and generated solid numbers. If you're looking for a no-brainer starter kit to get your sled rolling through the lights at the track or weekend cruiser, then this is one tough bargain to beat.
|BY THE NUMBERS |
|RPM ||LB-FT ||HP |
|3,000 ||397 ||230 |
|3,100 ||396 ||234 |
|3,200 ||400 ||243 |
|3,300 ||406 ||255 |
|3,400 ||412 ||267 |
|3,500 ||417 ||278 |
|3,600 ||421 ||288 |
|3,700 ||423 ||298 |
|3,800 ||426 ||308 |
|3,900 ||428 ||318 |
|4,000 ||429 ||327 |
|4,100 ||429 ||335 |
|4,200 ||430 ||344 |
|4,300 ||429 ||351 |
|4,400 ||427 ||358 |
|4,500 ||426 ||365 |
|4,600 ||426 ||373 |
|4,700 ||424 ||380 |
|4,800 ||422 ||386 |
|4,900 ||419 ||391 |
|5,000 ||416 ||396 |
|5,100 ||413 ||401 |
|5,200 ||410 ||406 |
|5,300 ||407 ||411 |
|5,400 ||403 ||414 |
|5,500 ||396 ||415 |
|5,600 ||388 ||413 |
|5,700 ||380 ||412 |
|5,800 ||372 ||414 |
|5,900 ||367 ||411 |
|6,000 ||358 ||409 |
|AVG ||410 ||349 |
|MAX ||430 ||415 |
|The Build List |
|MFG ||DESCRIPTION ||PN ||PRICE |
|THE FOUNDATION |
|Dart ||* SHP 372 Short-Block Assembly (block, cast crankshaft, hypereutectic pistons, forged 4340 rods, Clevite bearings, and coated cam bearings) ||31264344 ||$3,100 |
| ||* Iron Eagle 180cc Top End Kit (fully assembled 180cc cylinder heads w/ 64cc chambers, stamped steel valve covers, dual-plane intake manifold, intake/exhaust, head gaskets and ARP head bolts) ||01111112 ||1,600 |
|Comp Cams ||* Camshaft and Lifter Kit ||CL12-246-3 ||210 |
| ||* Timing Chain Set ||3100 ||50 |
| ||* Two-Piece Timing Cover ||210 ||265 |
| ||* Ultra Gold 1.5:1 Roller Rocker Arms ||19001-16 ||295 |
| ||* 7.800-in Pushrods (Intake/Exhaust) ||7372-16 ||111 |
|Milodon ||* SBC Oil Pan (right-hand dipstick) ||30901 ||208 |
| ||* High-Volume Oil Pump ||18750 ||41 |
| ||* Oil Pump Pick-up ||18316 ||57 |
| ||* Windage Tray ||32102 ||53 |
| ||* Windage Tray Install Studs ||81150 ||53 |
| || ||TOTAL ||$6,043 |
|ADDITIONAL ITEMS |
|ARP ||* Oil Pan Bolt Kit ||234-1802 ||20 |
| ||* Balancer Bolt ||134-2501 ||21 |
|Fel-Pro ||* Oil Pan Gasket ||1818 ||16 |
|Holley ||* 770 Street Avenger Carburetor ||0-80770 ||400 |
|MSD ||* Pro Billet Distributor ||85561 ||340 |
|TCI ||* 8-in Front Damper ||872002 ||86 |
| || ||TOTAL ||$883 |