photos by Darr Hawthorne
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."
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.
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.
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.