The fact that this build has...
The fact that this build has to be smog legal in California limited our choice of intake manifolds. We picked up an Edelbrock Performer, PN 3701, which incorporates provisions for the factory EGR valve. Bolted in place with ARP intake bolts, the Performer sits just a bit higher than the stock piece, but everything just fit under the hood.
After thoroughly cleaning...
After thoroughly cleaning the deck surface on our veteran block, Barron and Lee set our new Trick Flow lungs in place and torqued them down with ARP head bolts. Trick Flow also provided a full gasket set, one-piece chrome-moly pushrods, a pushrod-length checking tool (which we didn't need, since the ones they sent were right on), and a set of 1.6:1 roller rocker arms.
With our new heads and intake...
With our new heads and intake in place, Barron started putting the puzzle back together. Here, he's reinstalling something else we need to stay smog legal, namely our Camaro's smog pump. While we had the front of the Z's engine apart, we went ahead and installed one of Edelbrock's Victor-series high-flow water pumps. It took a bit of effort to get the stock bracketry to fit around it, but we consider the improvement in cooling ability worth it.
TFS' 175cc cylinder heads...
TFS' 175cc cylinder heads come with single valvesprings that accommodate up to 0.480 inch lift. We went for the optional 1.470-inch single-spring setup, which can handle up to 0.540 inch valve lift; the dual-spring version works with lift figures up to 0.600 inch.
The exhaust ports check in...
The exhaust ports check in at 67 cc. This is about 85 percent of the size of these heads' 1.50-inch exhaust valve, which is right where it should be, according to Kakiou.
Trick Flow's Small Chevy cylinder...
Trick Flow's Small Chevy cylinder heads feature a compact, fast-burn-style combustion chamber that measures 56 cc. "It's designed to be an efficient chamber design," says TFS's Kakiou.
The 175cc intake runners are...
The 175cc intake runners are designed to maintain air speed. "The volume is in the bowl so the cross-sectional area can be smaller for better velocity," says Kakiou. Keeping the intake velocity helps any motor, but especially our small-bore 305, build more torque.
We've mentioned the incredible...
We've mentioned the incredible array of accessory brackets and smog gizmos mounted on the front of our Z's engine. In the home stretch, we found that the tall valve covers Trick Flow sent wouldn't fit beneath all the stuff that needed to be mounted on, over, and around this area. We'll eventually switch to one of Fel Pro's extra-thick 1604 valve cover gaskets, but for now, we glued two regular gaskets together and installed them under the factory valve covers.
With the finish line finally...
With the finish line finally in sight, Lee installed a set of Autolite 3924 plugs and the MSD cap, rotor, and wires we happened to have on hand, and prepared to fire her up. To make sure our new hydraulic flat-tappet cam got a proper break-in, we ran Delo 400 diesel oil for the first 20 minutes then switched to normal 10W30 lube. K&N supplied oil and air filters, Lee reset our timing, and we were off to the street-legal drags before our date with the dyno.
|Small Chevy cylinder head airflow |
|(3.766-inch bore) |
|Lift (inch)||intake (cfm)||exhaust (cfm) |
|0.500||242 ||172 |
|Performance Progression |
|181 lb-ft @ 3,750 rpm |
|158 hp @ 5,070 rpm |
|60-ft: 2.47 |
|1/8-mile: 10.63 @ 66.27 mph |
|1/4-mile: 16.59 @ 83.15 mph |
|Add after-cat and cat |
|192 lb-ft @ 3,600 rpm |
|166 hp @ 4,800 rpm |
|Add TES headers |
|198 lb-ft @ 3,700 rpm |
|175 hp @ 4,900 rpm |
|Add Trick Flow heads, cam, Performer intake, K&N filter |
|226 lb-ft @ 4,400 rpm |
|211 hp @ 5,150 rpm |
|60-ft: 2.273 |
|1/8-mile: 9.884 @ 69.61 mph |
|1/4-mile: 15.40 @ 90.53 mph |