Chevy 350 Small Block Clone - Cloning Experiment

Follow Our Lead

Mike Petralia Jan 1, 2004 0 Comment(s)
Sucp_0401_01_z Chevy_350_small_block_clone Engine 1/14

Whenever we do an engine buildup, we're always trying to convey that if you follow our recipe you can get the same results. Well, we thought it was about time to see if there was any truth to that theory.

Back in October 2002 a friend of ours, Clayton Romie, was transforming his beat up old '71 Camaro into a serious g-machine and wanted some input. During a discussion about trick possibilities for his car, Clayton mentioned he had no idea who to go to for an engine build. We suggested that he build his engine modeled after Danger Mouse (DM) Part 6, which we had just recently finished at the time. He readily agreed and we set the ball in motion.

Sucp_0401_02_z Chevy_350_small_block_clone Dyno_chart_comparison 2/14

Sorting Out The Details
After a little research, we learned that Clayton's Camaro had a transplanted 305 under its hood. Not the best short-block to start such a build with, so I located a 350 four-bolt instead, which he paid a few hundred bucks for. Then I sent him to Probe Industries for a completely new rotating assembly, including forged pistons, a cast steel crank, new steel I-beam rods, Total Seal rings, and Clevite bearings.

The Probe pistons are a two-valve relief design that, combined with the 64cc GMPP Vortec heads I planned to install, would give the small-block, which by now had been crowned "Z-Zilla", which I've summarily shortened to just plain Zilla, a 9.4:1 compression ratio. The entire kit from Probe cost under $1,000, too.

Sucp_0401_03_z Chevy_350_small_block_clone Strapped_engine 3/14

I knew the COMP Cams XE262H camshaft I planned to install would push the stock Vortec's springs close to imminent destruction, I ordered Scoggin-Dickey Performance Center's (SDPC) specially-modified Vortec heads machined for larger valve springs that can take up to .550 lift. SDPC also supplied the Edelbrock Performer RPM air-gap manifold, and all the top end gaskets. To finish Zilla off, I installed COMP Cams 1.6:1 Magnum roller-tip rocker arms, COMP pushrods, and a COMP timing chain.

A Pertronix HEI distributor with Crane Extreme 9000 plug wires were connected to fire the Autolite No. 103 spark plugs and a Demon 750 vacuum secondary carb will feed the fuel. Since this engine was also intended to look as good as it runs, some Proform and GMPP dress-up items were bolted on, like the black valve covers and black timing chain cover.

Sucp_0401_05_z Chevy_350_small_block_clone Parts 4/14

GM's iron Vortec cylinder heads continue to deliver rock-solid performance in every test we make. But they also require all new parts (shown), because the Vortec's don't work with old components designed to fit the regular iron heads that have been around for so many years.

When it was done, not only did this engine run like a champ, it looked so good that we decided to put it on our August 2003 cover. Yep, that's Clayton's engine, with a pair of polished Proform valve covers instead of the black ones, and my big hairy arms running the valves.

On The Dyno
Since this engine was built along the premise that if we copied DM in its entirety, Zilla would make the same power. There was only one way to find out. We trucked Zilla over to Westech a strapped it onto their Superflow dyno. Right away the engine proved its worth, making over 415 hp and 440 ft-lb of torque. With some tuning on the Demon vacuum secondary carb, we managed to get peak numbers above 420 hp and 450 ft-lb of torque. That's more than DM made even in almost exactly the same configuration! But there was one, small difference: When I originally put DM together I intentionally left the Lunati pistons .050-inch down the bore to more closely mimic what I feel is very common on the street.

I built Zilla with the pistons at "zero" deck and with only two valve reliefs cut into the slugs (the Lunati pistons in DM have four) Zilla has a little more compression and less quench area. And I used a vacuum secondary Demon 750-cfm carb on Zilla, instead of the 750 double-pumper. Other than that, these two engines were identical. Although we have yet to figure out why DM has that annoying power dip between 3,600 and 4,600 rpm, there's no denying that Zilla, a virtual clone, made more power throughout the entire rpm range.

Sources

Westech Performance Group
Mira Loma, CA
951-685-4767
WestechPerformance.com
Comp Cams
Memphis, TN 38118
800-999-0853
http://www.compcams.com
Autolite
Danbury, CT 06810
800-890-2075
www.autolite.com
Probe Industries
Torrance, CA 90505
310-784-2977
www.probeindustries.com
Scat Enterprises
310/370-5501
scatenterprises.com
Milodon
Simi Valley, CA 93065
805-577-5950
www.milodon.net
Total Seal
Phoenix, AZ
(800) 874-2753
totalseal.com
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