Ch-Ch-Ch-Changes

Words and photos by Darr Hawthorne
8/9/04

roject Street FX was now headed for some changes. Our .30 over 454 Chevy big-block had reached the limit as we consistently ran 11.70's but it seemed as though the "cruiser" oriented engine was making about as much horsepower as it could. Weighing in at 2870 pounds our straight axle altered wheelbase street/strip Chevy II still needed to do double duty as a Friday night cruiser and drag strip runner all on pump gas.

Before any modifications could be made, we needed to have a baseline on an engine dyno to know where we were starting. At JMS Racing Engines in Monrovia, CA we found that test-bed and a nicer, more knowledgeable bunch of engine specialists would be hard to find. Three generations of the Johnson family bring a hands-on feeling to their 9000 square foot shop. As second generation owner Mike Johnson put it, "We are one of the few shops in the country that doesn't send any part of an engine out."

I spotted big and small block Chevys, 426 Hemis, Olds blocks and Fords in various states of build and have seen Mike at nearby Irwindale Dragstrip helping his customers on Thursday nights.

We unloaded our 468 cubic inch Chevy big block at JMS Racing Engines and a couple of days later dyno time became available so we could find a starting point. As I've mentioned before, this engine was originally set up for cruising and so much time had passed between the original build and its current life in the Project Street FX, none of us remembered what kind of compression ratio, piston domes or heads were on the engine. The only thing we knew for sure was there was a high volume Melling Oil Pump and an Isky Street/Strip 280 Hydraulic Mega Cam.

Once the engine was bolted in place on the JMS DTS Dyno, we still needed to wire the starter, distributor, plumbing and exhaust. At this time I was introduced to JMS founder and President Don Johnson. Don handles the dyno pulls for the company, having been involved over the last 25 years, along with son Mike in building race engines for Winston West Championship winners, road racing stock car champs, Bonneville record setters and NHRA national event winners. For the first pull Don was puzzled and quickly shut down the test when the oil pressure rose to 107.1 pounds and the engine delivered only 347 peak horsepower.

After checking the oil pressure lines Don determined that someone had probably not set up the oil pump correctly and we'd live with the huge reading. Don commented, "That pressure is probably costing you 20 to 25 horsepower." The second dyno pull started with total advance of 36 degrees and netted 474.1 lb/ft of torque with peak of 356.0 horsepower. Don backed the advance down a little and the next pull dropped a little torque and lost horsepower down to 352.4 hp.