Jim Smart
March 30, 2007
Photos By: Benton Jackson

Dry-Sump Oiling
Blair purchased a dry-sump pan that didn't fit his Mustang fastback. That's when Marvin designed a custom dry-sump system for him. Once Marvin generated the line drawings, he contacted Canton Racing Products in Connecticut. Doug Vine at Canton got Marvin dialed in with a superb, custom-made aluminum dry-sump pan for Blair's 427W.

This is the custom designed and fabricated dry-sump pan from Canton Racing Products. In this case, Marvin did the designing and Canton followed his specs. Note the careful thought given to oil scavenging-a windage tray designed to fit the Canton main stud girdle, which channels return oil to scavenge ports and is designed to handle hard acceleration and extreme lateral G-forces.

Girdle Fitment
Marvin's experience teaches us about things most of us never think of. Just because a stud girdle is fresh out of the box doesn't mean it's ready for permanent installation. Each and every main stud girdle's fit is based on what you have for a crankshaft, block, and connecting rods. This is why he stresses checking clearances on everything before final torque.

Marvin builds engines like seasoned street rod builders plan and execute street rods. First, he does a mock-up. In fact, he does several mock-ups just to be sure it's right.

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Marvin checks girdle clearances, stressing there should be a minimum of 0.060 inch between moving parts and the girdle. This is because of thermal expansion-as parts get hotter, they grow. He marks the girdle areas that will need machining to at least 0.060-inch minimum clearance.

How's It Slidin'?
What makes Marvin a cut above is his detailed, methodical approach to engine building. Have you ever had a part that needed a whack to fit? That's known as a pinch fit or interference fit. Pinch fit (no more than 0.001 inch) is acceptable to Marvin only when it is intended to keep a part secure, such as a distributor drive gear, a crankshaft damper, or a rear axle bearing. Cam and crank gears, for example, should slide on with finger effort. The key phrase is "slide on," which means a zero fit where parts fit without effort. According to Marvin, if you have to drive a cam or crank gear with a hammer, the fit is too tight. When zero fit doesn't happen, he massages parts until it happens. You should, too.

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Life Without Leaks
How many of you have built a fresh engine only to have it leak oil on your garage floor or driveway? Because we all need to be environmentally responsible, any leakage is intolerable. You can achieve a leakproof engine if you sweat the details during assembly.

Where possible, Marvin installs one-piece seals prior to crank installation. One-piece seals must be lubed with engine oil around the inside, then carefully installed on the crank. Never use oil around the outside-apply only a thin bead of silicone.

Did you know you can machine your two-piece-seal Ford block to accommo-date a one-piece rear main seal? If you're not up for that, did you know you can achieve a leakproof two-piece rear main seal? This is where Marvin sweats the details, never suffering the embarrassment of a leak. Remember, in both cases, the sharp lip must face inward to keep oil inside.

One-piece rear main seals are lightly lined with high-temp RTV silicone sealer around their circumference. Marvin does this before setting the crank. When he sets it, he uses high-temp RTV between the No. 5 main cap and block. He stresses allowing the RTV to set up for 24 hours before firing an engine for best results.

Two-piece rear main seals should be installed with gaps located out of synch with cap/block parting lines. In other words, stagger the gaps away from cap/block gaps. This virtually eliminates the risk of leakage. Use silicone between the cap and block as added insurance. Once cured, RTV provides a solid seal.