The Hemi chambers boast dual...
The Hemi chambers boast dual quench pads, which promote combustion efficiency and a quicker burn rate. The proof is in the pudding, as the TME heads required just 28 degrees of total ignition advance. A key benefit of a Hemi head is that it positions the intake and exhaust valves at opposite sides of chamber, freeing up space for massive 2.450/1.900-inch valves. This also means that the valves move closer to the bore centerline as they open, instead of shrouding up against the cylinder wall as in a Wedge head.
Granted most hot rodders are smart enough to realize that big ports don’t always work best, but the sheer cross-sectional area of a Boss 429 cylinder head is truly an awe-inspiring sight. You can literally stuff a tennis ball down the intake ports. TME offers two variants of its Boss heads, including CNC’d stock replacement castings as well as more aggressive 430 heads that flow 430 cfm out of the box. For the 477, Miller massaged the 430 castings up to 460 cfm at .700-inch lift, but they were clearly too large for the 2,500 to 6,500 rpm operating range dictated by EMC rules. As a fix, Miller added material to the port floors in an effort to reduce cross-sectional area and boost air velocity. The floor of these ports is so lazy that I don’t think adding material there hurt airflow at all. These weren’t ringer heads, and accurately represent what one of our customers can buy, Miller says. We cleaned up the ports a little bit, but otherwise the heads are untouched. At 477 ci, we didn’t feel that it was worth it to spend a lot of time porting the heads. Ultimately, I still think the ports were too lazy, and in the future, I’d like to pinch down the size of the ports even more to see if that increases air velocity. For our customers, we offer our heads with both round and D-shaped ports.
Even without the rockers in...
Even without the rockers in place, the TME Hemi head looks incredibly manly. Compared to a factory Boss casting, the TME head has a thicker deck, beefier head bolt bosses, and are cast from 356-T6 aluminum. The TME head also ditches the cumbersome factory O-rings on the deck surface and makes do with a regular head gasket.
The balance of the induction system was yet another instance where budget took precedence over ultimate performance. Considering that five of the top six qualifiers fielded EFI engines, the dual-plane intake manifolds mandated on all carbureted motors obviously choked them up big time. We wanted to run a single-plane intake with EFI, but ran out of time to finish it up, Miller says. The intake we ended up using is the same 42-year-old dual-plane unit that came equipped on Boss 429 Mustangs, which is the only dual-plane unit that’s out there for these motors. It was impossible to reach certain areas of the runners for porting, and there was as much as a 50-cfm variation in flow from one runner to the next. Needless to say, we affectionately called it the aluminum cork.
The unique valve placement...
The unique valve placement of the Hemi heads means that the exhaust pushrods are nearly an inch longer than the intake pushrods. The extreme angles and positioning of the pushrods also necessitate the use of Crane Z-bar-style lifters for additional clearance.
When the time arrived to put the TME 477 to the test, it ripped out 654 hp at 6,000 rpm, and 605 lb-ft of torque at 4,600 rpm. Taking its displacement into account under the EMC scoring system, this was good for a 17th Place finish out of a field of 38. Considering the unusually high attrition rate at the 2010 EMC, in which nine engines failed to make it out of qualifying without mechanical failure, a mid-pack finish from a privateer entrant on a modest budget is more than respectable. Regardless of where it finished, perhaps the most significant aspect of TME’s 477 is that it’s one of the best examples of the back-to-the-basics theme the 2010 EMC sought to recapture. This engine isn’t really all that scienced-out, and there’s a lot left in it. It uses mostly off-the-shelf parts, and anyone can build a motor just like it, Miller says. There’s a total of about $18,000 in it, which is a fraction of what the some of the big-name competitors spend on their engines. The good thing is, I don’t have to worry about what I’m going to do with it now that the competition is over. I can put it in just about any car and go cruising.