What We Did
Give an old-school 355ci a new look and a lot more power
Bottom Line
We gained 111 hp and 600 rpm on the dyno with a simple top-end kit
Don't let the exterior fool...
Don't let the exterior fool you, our little engine was kept in good order and produced decent power on the engine dyno. Our candidate for this project makeover consisted of a 355ci small-block that had a cam and roller rocker update at some point in its life. On the dyno, our gem made a reliable 365 hp at 5,500 rpm and 390 lb-ft at 4,300 rpm.
Mystery engines are always more entertaining than their crate/off-the-shelf brethren; not knowing what's on the inside can make them more or less interesting real fast. Our mystery motor could have high-compression pistons with forged internals ... or it could have a less-than-willing stock bottom end with a set of beat-up main bearings-it's just part of the deal when getting into a running car or engine secondhand. Originally, this little goose sat between the framerails of a second-gen Camaro, Henry D's project F73, to be exact. And as most of you know, we pulled this old slug from the car to perform a perfect summer makeover and also to give us as much room as possible for the chassis to be retrofitted with an all-new Detroit Speed suspension.
Considering our little mill was in perfect running order before we pulled it, we couldn't think of a better way to showcase its power potential than with a complete makeover-all of which would only call for bolt-ons while leaving the bottom end alone. We wanted to keep the costs down and keep the work performed to a minimum. The 355 featured a set of vintage cast-iron Corvette heads, a leaky oil pan, a stamped timing cover, and an older dual-plane manifold. Not exactly modern, but a solid performer nonetheless.
First to go were the finned-style...
First to go were the finned-style valve covers and cast-iron heads. Don't discount these just yet; we have another life planned for these in an upcoming build.
We outlined this build with a few basic rules: increase breathing with airflow, supply ample fuel, and maximize the power for the street. The major makeover components consisted of a set of heavy-puffing aluminum CNC-ported Brodix heads, single plane manifold, and a Comp valvetrain. While our unkown cam was pulled, we relied on a high-lift 0.520/0.540-inch intake/exhaust with 236/242 degrees of duration at 0.050-inch. It all sat on 110 degrees of lobe separation.
Topping it off is a gasket-matched SP1 single-plane manifold, also from Brodix. For good measure, we replaced our oiling system with all Moroso pieces, including a high-volume oil pump and pickup, and a deeper sump pan with screen. To maintain our street creed, we upgraded the fuel delivery with a 750-cfm Quick Fuel Technology carburetor and placed our confidence in a drop-in, ready-to-go MSD distributor.
We enlisted Westech Performance Center in Mira Loma, California, to get us baseline numbers from the original setup. With numbers in hand, we tore down the small-block and took care of its aging looks with a fresh coat of Chevy Orange paint.
Was it worth the effort? Considering it took all of two days-one for the teardown and rebuild and another spent on the dyno-111 additional ponies was well worth it, almost too easy to be honest. Tag along to see how we did it and how to do your own small-block makeover.
Once we got inside the motor,...
Once we got inside the motor, it was clear someone had given it attention. It featured upgraded hydraulic flat-tappets and beefier Comp roller rockers with a 1.6:1 ratio. We used a 5/8-inch socket to remove the old rockers.
Our cast-iron heads were in...
Our cast-iron heads were in pretty good shape, but they hardly stack up to the modern CNC-ported aluminum heads we're upgrading to. Add in the weight savings and improved cooling efficiency with the aluminum pieces and it makes them hard to beat. Since we are utilizing a complete Brodix top-end kit that comes with new bolts and gaskets, there was no need to keep the old stuff.
Removing the old timing gear,...
Removing the old timing gear, chain, and lower crank gear was a cinch. Then we pulled out the old stick and checked the cam bearings for wear. Our new Comp cam should really bump things up a notch. After all, with 0.520/0.540-inch intake/exhaust lift, the new cam should be able to take advantage of the larger Brodix lungs. We washed the cam in solvent to remove any rust inhibitors and foreign material, applied engine assembly lube, and slid it into place.
Moving right along, we installed...
Moving right along, we installed our brand-new double-roller timing chain with a billet gear and lower crank gear. All we had to do was line up the timing marks and set it in place with the supplied hardware and cam plate. We also installed the supplied plastic cam button and began to set up the engine for cam thrust.