Jim Smart
August 10, 2007

Step By Step

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Mufp_0603_01z Ford_stroker_engine TuneMufp_0603_02z Ford_stroker_engine Pressure
Most engine builders check only crankshaft endplay, but Marvin also checks camshaft endplay to ensure its 0.004-0.008 inch...
Mufp_0603_03z Ford_stroker_engine Camshaft
...with camshaft endplay of around 0.0010-0.0055 inch.
Mufp_0603_04z Ford_stroker_engine Connecting_rod
Marvin works the large end of the connecting rod with a proper radius. He does the same thing at the crankshaft journal to reduce stress.
Mufp_0603_05z Ford_stroker_engine Rocker_arm_stud
All engine parts should be carefully inspected and dressed for smooth operation. Rocker-arm stud threads should be chased and the shanks dressed with a fine stone for smooth assembly. For smooth operation, Marvin suggests removing any nicks or rises in mating surfaces. Nicks create high spots on machined surfaces that can cause problems later. Marvin uses only ARP rocker-arm studs due to the extraordinary 190,000-psi tensile strength.

Last month, we began our two-part series on how to get 400 hp and 400 lb-ft of torque from a 331ci stroker small-block fitted with factory Ford iron cylinder heads, and we learned something remarkable during the attempt. You can achieve 400 hp and 400 lb-ft of torque from 331ci and iron cylinder heads without selling the farm.

This month, we wrap up our Summit Racing/MCE Engines 331 Stealth build and show you why we fell a pinch short of 400/400. What's more, we're going to show you how to hit pay dirt and make 500 hp and 500 lb-ft of torque with a few easy modifications and these same iron Ford heads. Think we're just bench racing? Read on ...

Let's begin with the events of a steamy, hot Southern California summer day. We arrived early at Westech Performance to get our 331 Stealth small-block engine on the dyno. Right away, two things necessary to make the projected power weren't available at Westech on the day of our test. Without a velocity stack for the carburetor and the appropriate-sized 1-3/4-inch Hooker Super Comp headers, our numbers fell below 400/400. Despite these shortcomings, we did remarkably well on the dyno, turning in the broadest torque curve we've ever seen from a low-cube small-block Ford.

When Marvin McAfee of MCE Engines was planning our 331 Stealth small-block, he predicted numbers between 350-400 hp and 350-400 lb-ft of torque through the mufflers, which we essentially made. Marvin's goal was a streetable small-block powerhouse that would:

  • Have a single four-barrel carburetor;
  • Have a cam profile that would provide enough intake-manifold vacuum to operate power brakes and run other accessories;
  • Operate on pump gas;
  • Be able to run an automatic or manual transmission in a matter of hours, swapping a flexplate for a flywheel;
  • Have the minimal upgrades required to make at least 100 more horsepower from the same short-block and iron heads.
  • Under ideal circumstances, we should have achieved 410 hp and 404 lb-ft of torque with our engine package. Ideal conditions include:

  • A velocity stack on the carburetor with cold-air induction;
  • Ambient temperatures in the 60s with humidity in the 40-60-percent range;
  • A match-balanced flywheel. Westech didn't have a dyno-coupling package that would work with our match-balanced Milodon flexplate;
  • Hooker Super Competition headers with 1-3/4-inch primary tubes;
  • Open headers or a verifiable set of low-restriction mufflers.