Small-Block Engine Build - Son Of Sledgehammer

With the crank in the block, the rods and pistons were installed. Next, the piston-crown-to-block deck height was checked, so we could make a decision on the head gasket thickness for a power-oriented head gasket choice. If all the factory dimensions are spot on, the piston in a small-block Chevy will be .025 down the bore. This, plus a regular .043-inch gasket thickness, will result in a net piston-to-head clearance of .068 inch. This is way too much for optimal quench. The normal procedure when doing a serious build is to deck the block by as much as .030 for the pistons to be .005 out, but decking costs money. About the tightest you can go with stock-type components is .030. We can cut the clearance considerably by using a thinner steel shim gasket (which works very well with iron heads and block). Fel-Pro has these at .015-inch thick. Our piston-to-deck height averaged .024, so with a .015 gasket we cut the net clearance from an unsatisfactory .068 to .039, and at the same time bumped the compression by 0.6 of a ratio. So what's all this fuss over something as simple as gasket thickness worth? About 9 lbs-ft and 9 hp on a build such as this.

Cam Install And Timing
The cam for our engine was based on the numbers produced by a one-of-a-kind computer program available to professionals within the industry. With the flow characteristics of the EQ 23 heads plugged in, this program called for a 108-degree LCA. Should you find that our duration is a little on the big side for your own version, be aware that best results (with the same heads, compression, and displacement) will be had with a 108 LCA. Our cam was a custom single-pattern COMP Xtreme Energy hydraulic roller grind. The profile used was No. 3316 on both the intake and exhaust. This is being used with 1.6 rockers across the board. This combo provides a seat duration of 288 degrees, with a .050 duration of 236. The net valve lift is .555. Our thought on this cam is that it is about as big as can be used in a 350 before becoming too impractical for street use. If you want to go a little smaller, use a No. 3315 profile. Either way, if you're building a 350 with about the same compression and the same valve sizes, either of these cams will produce good results.

Next, the front cover, oil pump, and pan were installed. For the pan, we used Fel-Pro's top-of-the-line one-piece gasket. They certainly were not the cheapest, but they are reusable, and seal up first time every time. The oil pump was left stock. All we did was strip it, and check that it had not worn. Ours was in perfect working order.

The plastic adapter that couples the pump to the distributor driveshaft needed replacing, and these are usually found in a bottom-end gasket kit. With the pan in place, the short-block was complete. Now we can turn our attention to our star player, the EQ heads.

EQ Cylinder Heads
A major reason for using the new EQ 23 heads is our previous test on the Enginequest Vortec heads in the November 2006 issue (see "Budget Sledgehammer"). Once we heard that EQ had produced a 50cc chamber head, we were immediately interested. A major reason for this is that when chamber volumes this small are produced in a 23-degree head, there are some difficult intake valve shrouding issues to deal with. It is only by virtue of a very considered chamber design that a significantly positive result can be extracted from such a small chamber. The chamber design in the EQ 23 looks like it may trade a little high-end flow for a shape that burns more effectively. But high-end flow appears to not have been a big priority for this design, as most of the intended applications were for valvetrains using no more than .550-inch lift. Many oval track race classes call for .450 or .500-inch valve lift, with similar figures being common for budget performance street use. Based on the intended use, any loss of high-lift flow should be more than compensated for by a decent compression ratio that doesn't have a flame-impeding dome intruding into the chamber. To get an idea of where things stand in terms of compression, this 50cc head (with a flat-top piston having a net .030-inch piston-to-head clearance) will deliver a 12.7:1 compression ratio on a 350. As you might expect, we gave them the once-over on our bench:

The numbers were interesting in that they fitted the format exactly as expected; the chamber and intake port size (180 cc) appeared to be ideally suited to the intended application.

These heads are only sold bare from EQ, so it was necessary to build up ours. Some 2.02/1.6-inch valves were sourced from one of the bigger catalog companies for the sum of $136, and they were not the cheapest. The rest of the valvetrain hardware came from COMP. This included some No. 987 springs, and the appropriate retainers and keepers. The spring heights were measured, and shimmed to give the seat load suggested by COMP. At this point, we were in a position to save some cash because we had a ton of old head bolts in our scrap bin. If you only get a short-block, you'll need to get a set of ARP head bolts. The cheaper six-points are more than up to the job here. If you have enough used ones, be sure to wire brush the threads until they are smooth, so that tightening torque is translated into clamping torque. This is really important with steel-shim head gaskets. If there is any doubt about the threads, use new bolts.

Valvetrain
With the heads on, the next job is to mock-up the valvetrain for one cylinder, and determine the proper pushrod length. Using an adjustable pushrod length checker, the goal is to optimize the pushrod length such that there is an even sweep of the rocker across the center of the valve tip. We then ordered the proper length in COMP's Magnum series pushrod line. For valve lash, you need to consider what hydraulic roller lifters are being used, as the lash procedure could vary according to type. We reused the stock lifters because they were in perfect order, so the lash was done a quarter turn into the lifter travel. If you buy lifters, then COMP's Magnum lifters are designed to act more like a solid, and need to be lashed at zero to .002 inch.

Intake And Carb
The guys at Enginequest told us that these heads work well with an Edelbrock Super Victor, but a certain amount of port matching would be needed. In practice, we found that the Super Victor's ports were bigger than those in the EQ heads, so some epoxy had to be used to make things line up. Once the port matching was done, the intake was bolted up and the carb mounted via a 1-inch spacer. Our carb was a Barry Grant 750 Speed Demon. It should be noted that BG carbs are rated on wet flow, where Holley rates its carbs dry. This means the BG carb actually flows more on a dry rating. On this carb size, the dry rating is typically 25 to 50 cfm more.