The Big Wedge - Mopar Big-Block Engine

If you take the shorter of the two Mopar wedge variants, add substantially to the stroke, and then employ connecting rods measuring 0.342-inch longer than stock, you'll come to appreciate the spacious real estate Chrysler employed with these engines. Bear in mind that strokes over 4.150 inch create a nervous proximity with the factory internal oil pump pick-up, particularly at the factory crankpin diameter. For longer strokes, as used with this wedge, an external pick-up, such as the Milodon set-up used here, is the usual course of action. The piston compression height is dramatically altered with such a combination. Factory Mopar wedge pistons typically carried a compression height hovering in the vicinity of two inches. With this combination of stroke and rod length, the required compression height is reduced to a fraction over one inch. (1.092 inch to be exact.) The resultant loss in mass is dramatic, as is the reduction in reciprocating friction.

T&B took a novel approach with the piston for this engine, looking for minimal friction with the custom JE forged pieces. The piston employs a two-ring package, carrying a 1.2mm Total Seal gapless top ring, no second compression ring, and a 3mm oil ring assembly. We asked about the oil control with the two-ring setup, and Brenda informed us: "Actually everything looked really clean; it looked good in that way. On our oil ring we didn't go with the absolute lightest and went with just a little more tension." We suspect the piston and ring combination contributed to this engine's healthy output. The compression ratio was 12:1, and interestingly, we noted that there was no audible detonation with 91 octane pump gas while the engine worked the dyno. Brenda told us: "We ended up at 12:1, but we started off at 11.5 and had no detonation, so we bumped it up another half point. In the competition, we really didn't have any detonation like a lot of the other competitors. I think because we had a very tight quench clearance, and I think with the smaller chamber and the piston configuration, we had a very effective burn."

Back in the '60s, the Chrysler wedge heads had enough flow to breathe life into torquey 383- and 440-cube street engines. To be competitive in today's world, high-flowing cylinder heads are a must. Brodix B1 heads are just the ticket for supplying 506 cubes of raucous Mopar. These heads were modified by T&B, and fitted with Ferrea valves measuring a healthy 2.300 inch on the intake, and 1.72-inch on the exhaust. The valve size bias clearly favors the intake, and is part of the strategy to letting an in-line wedge head breath. Brenda did the port work, which involved epoxy filling of the floor in both the heads and the matching Brodix B1 intake manifold. However, given more time to prepare the engine, some changes might have been made. Brenda disclosed: "We did put too much filler in, looking back at it. We'd like to go less than that and see what it would do. I think we just went a little too far, and with about half that much in it, it probably would have given us a little bit better area. We matched the intake manifold and heads in that way."

A COMP Cams solid roller directs the valve operation, and does so with the authority of an immodest 261/265-degree duration spec at 0.050-inch tappet rise, and 0.735-inch lift. The idea is to really open the window for airflow into the engine. The relatively tight lobe separation angle and shallow installed centerline are aimed at bringing impressive torque to the arena by the intended peak operating speed of 6,500 rpm. Manley springs, retainers, Smith Brothers pushrods, and Brodix 1.7:1-ratio rockers work in concert to deliver the motion to the valves as the cam lobes intend.

We were fortunate to see the T&B Mopar in action at the Engine Masters Challenge event at World Product's Long Island, N.Y. facility, and even more so to meet the people behind the engine. T&B Performance Machine is a family business, and that was demonstrated when Tom, Brenda, Grandma, and all the kids came to enjoy the week's events and the thrills of competition. The engine was competitive, and one of the cleanest running of all the entrants under the constraints of trying to maximize power within the 91 octane pump gas rule. Competing allows this team of builders to experiment in a way that would otherwise seem impractical. As Brenda told us, "One of the real fun things about the Engine Masters Competition is that we get to try things that we wouldn't usually get a chance to on a customer's engine. Engine Masters gives us a good opportunity to try different things, and see if they are beneficial to encourage our customers to do as well." We look forward to seeing what they bring this year.