Thunder From Down Under – testing the new CHI 3V Cleveland Heads
Muscle Mustangs and Fast Fords tests the new CHI 3V Cleveland Heads
Courtesy of Muscle Mustangs and Fast Fords
Here in the states, the 5-liter Mustang revolutionized an entire industry. Think about how many different cylinder heads or intake manifolds were introduced for the Windsor-based motors before the EFI Mustang came along. Basically, if you were looking for a set of performance heads for your Windsor before the 5.0 market ramped up in the early ’90s, you were stuck with a set of ported stockers.
In the 15 or so years after getting up to speed, there are literally dozens of heads and intake manifolds to choose from. Before the avalanche of Windsor heads, if you really wanted to go fast with a Windsor Ford, you performed the necessary modifications to install a set of 351 Cleveland heads on it. While the four-barrel Cleveland heads certainly out-flowed their 351 Windsor counterparts, modifications were necessary to perform the Cleveland-Windsor head swap. The easiest route was to simply install a set of Boss 302 heads rather than the 4V Clevelands . The reason for choosing the Boss 302 heads was that unlike typical Cleveland motors, the Boss 302 sported the clever canted-valve headgear, but was all Windsor below the head-line.
The major difference between the Cleveland engine family and the Windsor (aside from the unique valve layout for the former( was the water passages. On the Cleveland , the coolant flowed through the front cover. On the Windsor , it flowed through a crossover in the intake manifold. The difference in coolant flow necessitated a difference in the cylinder heads and attending intake manifold. Cleveland heads featured water passages in the deck surface, while Windsor heads featured coolant passages in the intake surface. Other than this difference, Cleveland heads and Windsor heads will physically interchange thanks to a common bore spacing and positioning of the head bolt holes.
Installing Cleveland heads on your Windsor was a simple matter of plugging the holes in the deck surface and drilling the appropriate holes in the intake surface. The Boss 302 heads already featured this conversion, but needless to say, Boss 302 heads are not simply laying around the wrecking yard.
Part of the problem with producing an aftermarket Cleveland head is choosing the appropriate port configuration. The small-port, low-performance heads offered by Ford for the Cleveland-based motors were labelled as 2Vs for the use with a two-barrel carb and intake manifold. Naturally, the high(er) performance four-barrel versions were designated as 4Vs. The difference in the intake dimensions between the 2V and 4V heads preclude interchange ability of the intake manifold.
Both 2V and 4V heads had their strengths and weakness. The 2V heads offered the less desirable open chamber, but a reasonably sized port entry, where the 4V had the smaller closed combustion chambers combined with intake ports seemingly sized for a 500-inch Pro Stock motor. Naturally the 4V ports easily out- flowed the smaller 2V ports, but not in proportion to the change in port size.
The ideal combination for an aftermarket Cleveland head would be a 2V port volume offering 4V flow numbers combined with a closed combustion chamber. Lucky for us Yanks, the Aussies, or more specifically the gang at Cylinder Head Innovations (CHI), produced Cleveland-based cylinder heads that offered exceptional flow characteristics, reasonably sized port volumes and closed combustion chambers. Wonder of all wonders, the much-improved 3V heads from CHI also feature aluminium construction.
Cylinder Head Innovations actually offers the 3V head in two distinct configurations, with both 185cc and 218cc intake port volumes. It also offers a CNC-ported version of the 218cc port that is reported to flow a whopping 340 cfm according to CHI. In actual fact, the ported 218 heads sent to us for testing checked in at 350 cfm.
As mentioned earlier, the 3V heads featured port dimensions (and placement) that perfectly match neither the standard 2V or 4V Cleveland heads. Both 2V and 4V manifolds will physically bolt to the 3V heads, but both will feature a port mismatch to a lesser or greater extent. While the intake ports are unique to the 3V, the CHI heads do share a number of components with the production Cleveland heads, such as valve angles (9.5 x 4.25/9.5 x 3), locations and even (4V( length. The 218cc 3V heads come with 2.150 intake valves and 1.65 exhaust valves. The smaller 185cc heads make do with slightly smaller 2.08 intake valves. The heads featured cast-iron valve seats (compatible with unleaded fuels) measuring 2.255 x 5/16 and phosphorus bronze valve guides.
Due to the unique port shape, the 3V heads come with CHI specific intake gaskets, along with Fel Pro recommendations for the combination-specific (Windsor or Cleveland) head gaskets. CHI also provided torque specs for the head bolts and rocker studs, as the 3V heads required the use of adjustable (1.73 ratio) roller rockers. We sourced roller rockers, rocker studs and guide plates for the CHI heads from Comp Cams.
The unique port size of the CHI 3V heads did present a possible dilemma, namely, which intake manifold to use. Whether stock or aftermarket, neither the 2V nor 4V were what could be described as a perfect match for the aluminium heads. Once again, CR1 recognized this potential problem and came to the rescue with its own intake manifold(s) designed to not only mate up perfectly to the revised 3V ports, but match from a power production stand point.
Recognizing that the 3V heads will be used on a number of displacement and deck-height configurations, CHI designed a variety of different intake manifolds to work on everything from the 8.2-inch (deck height) 302s, through the 9.2-inch Clevelands, to the 9.5-inch Windsor-based Clevors. It even has intake manifolds designed to run the larger 4500 Dominators carbs for maximum power production. Given the fact the flow numbers suggest the 3V heads will support over 700 hp, the Dominator flange intakes might well be necessary on a wild Stroker combination.
Knowing you wanted to see power numbers, we decided to build a Cleveland test motor and run a back-to-back test to verify the potential of the new 3V heads. As luck would have it, I wasn’t forced to go the wrecking yard route with this Cleveland . My turbo buddies at HP Performance had a very used, but mostly complete, 351 Cleveland they would let me have for a song. In fact, they even offered to haul it out from Roswell , New Mexico , to sunny SoCal during one of our test weekends. It is amazing what enthusiasts will do for my wife’s lasagne.
Though thoroughly worn out, the 351C had all of the major components, and wonder of all wonders was of the more desirable 4V variety. This core would provide us the opportunity to compare the more performance-oriented 4V heads and intake to the CHI 3V heads and intake.
After a teardown, we made the decision to use the 4V motor not just as a test mule, but also as a performance street build-up of sorts. Sure, it would serve its purpose as a test bed for the 4V/3V shootout, but it might also serve to illustrate what is possible for current 351 Cleveland owners. To that end, we decided the best route to improved power is additional displacement. The cubes came courtesy of Coast High Performance, which rebuilt the 351 using a 3.75 Stroker crank. When combined with a .030-inch over bore, our Cleveland now checked in at a full 383 cubic-inches.
Owing to its street-car roots, the compression on the 383 was kept to 10.0:1. Though a tad on the high side for the stock iron 4V heads (unless the chambers have been polished), we figured the extra squeeze would work well with the detonation suppressing qualities offered by the aluminium 3V heads.
In keeping with the street-is-neat theme, we stuck in a hydraulic flat-tappet cam rather than going with a racey (and pricey) roller (hydraulic or solid). The beauty of the hydraulic flat tappet cam was that it could be installed with a minimum of fuss, since the motor was originally so equipped. This meant the 4V heads could be run with the stock rocker system, though we did upgrade to roller rockers to make the most of the lift and duration offered bytheXE284H cam. Hot for a hydraulic flat-tappet cam, the XE284H offered a 240/246 duration split with a .584/.58S lift split all with a 110-degree lobe separation angle. Comp Cams supplied the hot hydraulic cam along with matching lifters, a double roller timing chain and the required valve springs and retainers.
The used 4V iron heads were given the once over by Ford Performance Solutions, consisting of a simple valve job, new seals and a coat of fresh paint. More power is obviously available from porting, but we wanted to see how the CHI 3V heads compared to (a known quantity) the stock 4V heads. Though worn, we retained the stock intake and exhaust valves on the 4V heads, but they sealed perfectly after the valve job. New Comp springs, retainers and oil seals and our 4V heads were ready to go. The final touch was to install the Comp 1.73-ratio roller rocker conversion, but this could only be done after bolting the heads in place as the conversion guide plates did not allow access to the head bolts.
The cast-iron 4V intake manifold was thoroughly cleaned and readied for action. We chose to top the stroker with an 830 HP Holley carb. Hooker supplied a set of long-tube 1 7/8-inch headers for our Cleveland test motor, while MSD came though with a direct replacement distributor. Additional goodies included a set of Ford Racing cast-aluminium valve covers and chrome thermostat housing along with a Meziere electric water pump. The idea was to optimize (with timing and jetting) the 383 stroker with the stock 4V heads and intake and then install the CHI heads and intake. Naturally the timing and jetting would be optimized for the new aluminium heads and intake as well.
We fully expected and were rewarded with an exceptional torque curve from the combination of the extra cubic inches and dual-plane (stock) 4V intake manifold. Obviously, there may be better intake systems available for this combination than the stock cast-iron 4V manifold, but we could find no Edelbrock Performer RPM Air Gap intake or its dual-plane equivalent for this test. After dialling in the timing and fuel curves, the 4V 383 produced peak numbers of 438 hp and 450 Ib-ft of torque.
We were quite happy with the torque production of the Stroker, as the street-oriented 383 pumped out 439 Ib-ft at just 3,000 rpm. In fact, torque production from the 383 exceeded 430 Ib-ft from below 3,000 rpm to 5,000 rpm. The relatively light valve springs (112 pounds seat/310 pounds open pressure) limited engine speed to 6,000 rpm before we experienced valve float. Remember that the larger Cleveland valves require somewhat more spring pressure than the smaller Windsor valves to maintain equal control.
After verifying the baseline numbers established with the stock 4V heads and intake, it was time to swap on the CHI components. Right off the bat we can say the aluminium components were much more pleasant to work with. The iron 4V heads and intake were heavy to say the least. The CHI 3V heads went on without a hitch, requiring only that we plug the holes in the front of each head designed to facilitate external coolant flow for Windsor applications.
Since the 3V heads retained use of the stock 4V valve lengths, the pushrod length was the same for both heads (though we did verify this fact by checking the pattern on the valve tips). Unlike the hydraulic flat-tappet cam-specific 4V heads, the CHI heads were already set up for stud-mounted roller rockers. The rocker studs and (standard Cleveland ) guide plates were sourced from Comp cams, while the 1.73 ratio roller rockers were carried over from the converted 4V heads.
The aluminium 3V heads were topped off with a CHI single-plane intake. The intake was designed specifically for use with the 3V heads. As with most single-plane designs, the CHI intake featured four long(er) and four short runners, owing mostly to the position of the ports relative to the common plenum located under the carburettor. The surface finish of the cast-aluminium intake was first rate.
After swapping on the 3V heads and intake in place of the factory 4V components, we were rewarded with an impressive power gain. It improved the power output of the 383 Stroker by a whopping 86 hp at 6,000 rpm (from 438 hp to 524). The gains were all the more impressive considering the fact that our mild combination could not take full advantage of the additional airflow offered by the CHI heads and intake. On the right combination, the 3V heads could well support 700 hp or more, while the stock 4V heads would do well to reach 500 hp (limited mostly by exhaust flow).
As expected, the CHI single-plane intake shifted the torque curve, in this case by some 1,200 rpm. The 383 now produced peak torque at 5,200 rpm. This elevated torque peak strongly suggested that the combination had more to offer, but was possibly hampered by insufficient valve spring pressure. Note that the dual-plane intake allowed the stock 4V combination to out-power the CHI combination up to 4,000 rpm. Had the 3V heads been run with a dual-plane intake we expect it would have easily out-powered the stock heads even down low given the superior airflow and reduction in port volume. Regardless, the CHI 3V heads and intake had shown their worth by upping the power output of our 383-stroker Cleveland by an amazing 86 hp [and peak torque by 41 Ib-ft]. So impressed were we with the 3V heads (and intake) that we may go to the trouble of testing them against a set of APR 225 heads on a modified Windsor motor in the near future!!!
Having recently completed no less than 30 Windsor head swaps, I decided to turn my attention to something new. A Stroker Cleveland with a set of new Australian CHI 3V aluminium heads seemed like the perfect departure.
The first thing a Cleveland enthusiast will likely notice about the CHI 3V heads is the aluminium construction. Feather weights compared to an iron 4V head, the CHI 3V heads also offer a number of other impressive features.
The CHI 3V heads Featured Ferrea performance 2.125″, stainless steel intake valves and matching 1.6250″ exhaust valves. Compare these to the typical 2.02/1.60″ combination usually run in most aftermarket Windsor heads. The 3V heads also featured 64cc combustion chambers, though milling could bring this down to increase the compression ratio.
Our heads were shipped bare with Ferrea Valves, so we outfitted the new heads with springs and titanium retainers from Comp Cams. The springs offered 135pounds of seat pressure, just about perfect for our hydraulic flat – tappet cam.
The exhaust ports featured a conventional Cleveland bolt pattern, meaning headers and stock exhaust manifolds will bolt straight up. The exhaust port has been the Achilles heal of the Cleveland , but CHI have found a way to dramatically improve the exhaust flow rate while minimizing the port volume.
The most significant feature of the CHI 3V head was the intake port. Looking all the world like the smaller 2V intake port, the 3V offered the port volume of a 2V with the flow rate that easily exceeded the larger 4V. Big flow from a small(er) port means impressive port velocity.
The Cleveland motors differ from the Windsor Motors by the way of coolant flow. Clevelands flow water through the head into the front cover, while Windsors flow coolant through the intake manifold. The CHI 3V heads can be used on a Windsor , but it is necessary to plug these coolant passages in the deck surface.
When running the 3V heads on a Windsor two holes in the front of the CHI heads are used for external coolant passages. It is also possible to drill holes in the intake mating face. These holes were plugged for our Cleveland application.
This shot illustrates the difference in port dimensions between the CHI intake and the conventional 4V manifold. Note the dramatic mismatch between the 4V gasket and the CHI intake port.
The 4V intake ports are huge, but unfortunately the flow rate is not in relation to the port volume (0r dimension). Though significantly larger than the 3V head, the 4V intake port flowed some 75cfm less.
To maximise the performance of its 3V heads, CHI also supplied one of its new Engine Masters series intake manifolds. Since neither the 2V or 4V intake would mate perfectly to the 3V intake port, CHI saw fit to design a series of intakes to work with its new cylinder head. The single plane design obviously optimized mid-range and top-end power.
Here is our stock 4V Cleveland head after the gang at Ford Performance solutions performed a valve job and installed the springs from Comp Cams.
We ran the 4V heads with the factory 4V (dual plane) intake manifold. A thorough cleaning and a fresh coat of paint was all the stock 4V manifold needed for testing.
Coast High Performance transformed our beat-up 351 Cleveland core motor into a ready to run, 383 short block.
Due to the unique valve angles, the Cleveland heads required valve reliefs (intake only) adjacent to the cylinder wall. Notice that the top of the cylinder has also been relieved to further improve airflow.
The extra displacement came from a 3.75-inch stroker crank. CHP also supplied a set of forged connecting rods to complete the stroker short block.
The stroker crank required a spacer to properly orient the timing gear for this Cleveland application. This is not uncommon when running a Windsor-based stroker crank in a Cleveland block. Using the original Cleveland balancer, we machined the necessary spacer. These spacers are also available through Ford racing, though none were available in time for our test.
Our stroker Cleveland was destined for street use, so we installed an Xtreme Energy XE 284H hydraulic flat tappet cam. We liked the set-it-and-forget-it adjustment procedure associated with the hydraulic cam.
Comp cams also supplied the necessary 1.73 ratio roller rockers for our test. The roller rockers were run on the 4V heads using a Crane rocker conversion kit.
To ensure adequate fuel delivery to our stroker, we employed a Holley 830HP carburettor. The Holley HP carb never missed a beat on either combination.
We found a few holes in the stock Cleveland oil pan, so on went a Milodon stock replacement Pan. WE installed a high volume oil pump as well.
Cleveland valve covers can be hard to find, but we found this trick set of finned aluminium covers in the Ford racing catalogue. Ford racing also supplied a thermostat housing.
Hooker shipped out a set of 1 7/8-inch long tube headers for our Cleveland test. The long primaries were designed to enhance torque, just the thing for our stroker motor.
Equipped with stock 4V heads and intake, the 383 stroker produced 438hp at 6000rpm and 450ft/lb of torque at 4000rpm.
After running the stock 4V components, we installed the CHI3V heads. Since the author forgot to order the guide plates in time for the test, we were forced to make our own using Chevy Big-Block plates. We cut them in half and bolted them down after aligning the rocker tips. This system worked fine for the minimal amount of dyno time, but you would want to weld a tab to connect the two guide plates for extended use to eliminate the possibility of movement.
The stock 4V intake was ditched in favour of the Engine Masters Series from CHI. The single-plane manifold featured a raised carb pad to maximize the plenum volume and allow the air/fuel mixture plenty of time to make the turn into each port. A great deal of time was spent on the design to maximize performance when combined with the 3V heads.
On the dyno, the CHI combination increased the peak power output by a whopping 86hp to 524hp. Though the single-plane manifold shifted the torque curve higher in the rev range, the peak torque was up as well, from 450ft/lb at 4000rpm to 491ft/lb at 5200rpm.