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Ford's Boss 429 Mustang - Stone Pony Or Rock Star?
An Overview Of Ford's Boss 429 May Change Your Perceptions
The Nov. 1969 issue of Hi-Performance CARS magazine had two interesting articles on Boss 429s. One was a story on Wayne Gapp's AHRA-style '69 Mustang gas Funny Car, the other, and our focus here, was a report on the progress of Tom Larkin Ford's '69 Boss 429 B/stock racer, entitled Stone Pony or Strip Stallion?. The article articulated the difficulties in getting the Boss to be competitive in class-the record holder at the time being a '67 427 Fairlane at 11.85 at 119 mph.
Several obstacles were discussed by author Roger Huntington that are enlightening. First, it's pointed out that as delivered, the Boss had pretty sloppy tolerances, i.e. chamber volumes, crank balance, and so on, requiring an extensive blueprint job. Next came discussion of the weak hydraulic camshaft which all early S-code engines (and early T-code engines) came with. The mechanical cam Ford substituted thereafter was clearly the way to go in the eyes of the Larkin crew and other sources we've seen. Also mentioned was the handicap that the comparatively mild 10.5 CR and 735cfm Holley dictated, as in class, much of the competition had more of both, yet rules did not allow changes from OEM specs.
More factory hampering appears to have come from the mean-looking Boss hoodscoop, which in reality was a functional failure at speed. Again in the stock classes, rules prevented altering the scoop, but by removing the air cleaner/hood seal, the Larkin car picked up an unbelievable half a second and 10 mph. Rather than feeding the desired cool air, the scoop seemingly choked the engine for air at high speeds, and removing the assembly allowed unlimited underhood air for the engine to inhale. Moral to the story-hot air is better than no air. Unfortunately, the competition had more effective cold air induction, again placing the Boss 429 at a disadvantage. At the time of the article, it was noted that the Larkin Boss had run a best of 12.09 at 118, or about 0.25 off the national record. In many ways, the CARS story pointed to encouraging signs that the Boss 429 had big potential, particularly in classes where carburetion, compression, and hoodscoop design were unlimited.
Yet another enlightening story appeared in the Jan. 1970 issue of Car Craft, which paralleled some of the CARS criticism, and highlighted additional problems. Everyone lambasted the original hydraulic cam, but CC pointed to a heavy valve package, which, particularly when teamed with the hydraulic cam, resulted in valve float above 5,400 rpm. Considering that the cylinder heads were designed to function all day at 7,200 rpm in stock car competition, such rpms were way short of optimal. As well, the 429 internal dimensions of a 4.36-inch bore and 3.59-inch stroke inherently means the engine isn't a torque monster, so rpm capability is critical.
Car Craft also roundly criticized Ford's Product Acceptability Standard, or P.A.S, claiming this corporate policy mandated that all Fords, no matter their intent, "must start when the engine is hot, start in cold weather, idle, run in traffic in Fourth gear, and run smoothly at 20, 60, or 80 mph, just like a Lincoln Continental. In addition, the P.A.S. demanded that the engine compartment, passenger compartment, and overall noise levels must not exceed a certain maximum." Author Terry Cook pointed out that high-end Mopars weren't saddled with such limitations, and added that "until Ford loosens its P.A.S. for performance cars, it will continue to take a back seat to GM and Chrysler in performance." Car Craft went on to review separate performance efforts being made by Foulger Ford, Dave Lyall, and Wayne Gapp, and ended with a telling Boss 429 test session on the engine dyno at Crane Cams. When the best pull yielded 386 hp at 6,000 rpm with Ford's updated mechanical cam and dyno headers, Car Craft concluded "the Boss 429 is touted as a performance engine, but dyno figures don't support this claim to date." Ouch!
When was the last time you saw a Boss 429 Mustang with the front wheels sky high? Ford dyno technician Dave Lyall did it regularly in 1969 and 1970, actually campaigning two similar-appearing '69 SportsRoofs supplied by Ford. One was a preproduction '69 durability test car that Lyall turned into a stripped out AHRA match racer, the second was a legit Boss 429 that first ran SS/D, then "heads up Super Stock" (AHRA predecessor to Pro Stock), and NHRA Pro Stock. Both cars ran Boss 429 engines as Lyall helped Ford engineer Wayne Gapp with development work on the new race engine, and both cars would also be updated with '70 sheetmetal. Lyall explained, "We couldn't quite get the Boss to run at the national record in Super Stock, so we eventually made it a Pro Stocker. I remember the first honest to goodness "Pro Stock" race at the 1970 Winternationals. Unfortunately, we broke, so obviously didn't do very well. Not long afterward we went to the Super Stock Nationals at York US 30, and did quite well. I lost in the quarterfinals to eventual winner Ronnie Sox in his Hemi 'Cuda, he'd just outrun me over the last 300 feet or so. As the top loser, I came back into the mix when one of the remaining cars couldn't make the call, and Ronnie did it to me again-obviously he mile an hour'd better." (Dave Lyall photo collection)