April '19

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APRIL 2019 THE SHOP 41 PRECISION ENGINE distributor was removed and the oil pump drive shaft was rotated with a cordless drill to pump oil through the engine for priming. Initial timing was set at 25 degrees. All timing adjustments were made at the MSD crank trigger sensor (by moving the sensor in relation to the trigger wheel). Gressman allowed her to run for a few minutes at around 1,400- 1,500 rpm while monitoring the vitals. We immediately had about 65 pounds of oil pressure (which bumped to 80 psi during pulls), and no leaks occurred anywhere on the motor. After allowing the engine to warm up, he shut her down and re- checked hot valve lash, setting all valves at 0.028 inches. The first hard pull, with timing set at 27 degrees, netted 1,098 hp at 7,150 rpm. A second pull, with timing at 30 degrees, yanked 1,105 hp at 7,150 rpm. The final pull, at 32 degrees timing and with the camshaft retarded 3 degrees, produced 1,115 hp at 7,150 rpm. Torque wasn't as high as we expected, to be honest. The best we pulled (on the first run) was 882 foot-pounds. On our best horsepower pull, the highest torque reading was 863.4 foot-pounds. We expected torque to be in the mid-to-high-900 range. But again, these are still respectable numbers, and with further tweaking, we feel very confident that there's more to be had. See image 3. Gressman felt comfortable that with more timing tweaks, and per- haps switching to dual 1050 carbs, we would likely hit in the range of 1,200 hp. Unfortunately, we had only a limited timeframe to use the dyno, but for an initial out-of-the-box run, 1,115 hp isn't bad at all. I was surprised at how incredibly responsive the engine was. She snapped revs quicker than a hungry dog chowing-down a bowl of Kibbles. And the horrific shriek she made at high revs was both scary and wonderful. She's definitely a nasty li'l rat. I have no illusions that we've created the best of anything. I know full-well that builders could pull greater horsepower and torque numbers with various tweaks to the cam profile, ignition timing and fuel delivery. But, what we've accomplished in this build series definitely lays the groundwork for this type of build. We hope you've enjoyed the project and, above all, we hope that the information we've provided is of some benefit. MIKE MAVRIGIAN owns and operates Birchwood Automo- tive in Creston, Ohio, where he builds custom engines, street rods and performs vehicle restorations. He has written thousands of technical articles, as well as nine books on automotive technology during the past 30 years. Mike can be reached at 330-435-6347 or Visit Birchwood's website at Why is this guy smiling? Hey, the assembly is done, and it's been a long time coming. Maybe I can sneak in a day or two for some fly fishing? PRODUCT SUPPORT Thanks to the following for their involvement in this project… ARP INC., ATI PERFORMANCE PRODUCTS, BG FUEL SYSTEMS, CAM LOGIC (BOLTON CONDUCTIVE SYSTEMS), CAM MOTION INC., CLEVITE ENGINE PARTS, CRANE CAMS INC., DART MACHINERY, DIAMOND RACING PRODUCTS, FALL AUTOMOTIVE MACHINE, GEAR HEAD TOOLS, GOODSON TOOLS & SUPPLIES, GRESSMAN POWERSPORTS, HOLLEY PERFORMANCE PRODUCTS, JESEL VALVETRAIN INC., JONES RACING PRODUCTS, LUNATI, MANTON RACING PRODUCTS, MEZIERE ENTERPRISES INC., MOROSO PERFORMANCE PRODUCTS, MSD IGNITION, PRO-FILER PERFORMANCE PRODUCTS, RACE PUMPS, ROYAL PURPLE LTD., SUNNEN PRODUCTS CO., TRICK FLOW SPECIALTIES

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