 An HEI on a Ford? That's the...  An HEI on a Ford? That's the way we went, and the Performance Distributors unit with its micro timing adjuster (knob on lower left) proved just the ticket. |  At the power level we were...  At the power level we were targeting, an Edelbrock Super Victor, rather than a Victor Jr., is the way to go. Previous testing on nominally 600hp engines have shown the Super Victor is worth 15-20 hp over the Victor Jr. |  The HP 950 for our project...  The HP 950 for our project motor was custom built for Mesa Balancing by a Cup Car carb builder who builds carbs only for specific applications. This custom build service adds between $50 and $100 to the price of the carb, but its worth repeatedly shows up in the dyno numbers. |
Now was time to start fine-tuning. Dropping the jet sizes by two numbers all around saw a little more power. This netted 4-5 lb-ft more everywhere, and about 6 hp at the top end. Some steady-state pulls under full load were made and held a while. This showed we were about dead-on from the mixture standpoint. Now was time to dial in the timing. The 8 degrees initial we used as our starting point produced 30 degrees total, which was all in by 3,000. We used the distributor's thumb wheel micro timing feature to gradually dial in some more timing. After about 10 pulls, we had optimal timing at 33 degrees total. An optimal total advance this low is a good indication that the burn is taking place fast and effectively.
Using a Meziere electric water...
Using a Meziere electric water pump is typically worth 6-7 hp for engines peaking in the 6,000-6,500 rpm range. We used a pump like this one for the power advantage, and the convenience of dyno setup.
The lowest we could pull this 425 down to on the Mesa Balancing dyno was a shade under 3,200 rpm. At 3,200 rpm, it was cranking out a very impressive 517 lb-ft of torque. That's 17 lb-ft more than the peak torque of the Corvette LS7, which is virtually the same size as our stroker Windsor. From 3,500-3,900, the torque curve drops just below the 500 lb-ft mark in what can best be described as the intake manifold tuning hole. Here the length of the intake runners and the exhaust just don't coincide to do as much to assist cylinder filling as they could, but as 4,000 rpm comes around, things get wild. Here the engine comes on the cam; the intake, exhaust, and the big torque numbers reflect just how well this combination is working. We repeatedly saw peak numbers of 572 lb-ft, and on one run 575 lb-ft. That works out to a shade over 1.34 lb-ft per cube, and that (for a low-cost 10.5:1 pump-gas motor) is really good. As for horsepower, this Mesa-built stroker could hit the 607hp mark on every pull after the setup was perfected.
With this build we have shown once again the old adage that getting the right combination is the key to success, but that doesn't come as any surprise. What is more of a surprise is how cost-effective this build was. Sure, it's not at the bottom of the "budget barrel," but in terms of being reasonably priced, it's among the best budget-conscious builds we have done in a long time.
Dyno Test * 425CI Small-Block Windsor Peak HP: 607 at 6,200 rpm
Peak TQ: 572 lb-ft at 4,500 rpm These are the kind of results that can be expected when the combination is right. Other than the dip caused by the combined effect of the intake and exhaust tuning at 3,700 rpm, this 425 was good for 500 lb-ft plus from about 2,900-6,300 rpm.