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Questions and Answers - What's Your Problem?

Jeff Smith Answers Some Of Our Readers' Questions

These heads were decent production castings for a mid-'80s 305, and we think these were even used in the short-lived L69 305 Z28 Camaro engines rated at 190 hp. But bottom line, there are dozens of heads out there that will flow more air than even a highly modified 416 head. Let's look at your options. Our first recommendation from a budget standpoint is the GMPP iron Vortec heads. These heads not only offer outstanding port flow at below 0.500 inch valve lift, but they also do it with a small intake port that delivers excellent flow velocity, which equates to better torque. On several small-block Chevy engine packages we've built over the years, we've made 375 to 390 hp with a camshaft similar to the one you mentioned. These heads will require a dedicated, Vortec-style manifold. The best one we've found is the Edelbrock Performer RPM Air Gap. The Vortec heads will also need a different valvespring and machined valveguide bosses to accommodate the additional lift of a 0.490-inch-lift cam. The best deal here is to buy a set of modified Vortec iron heads from Scoggin-Dickey Performance Center. The company offers a modified head with 0.525-inch-lift valvesprings and guideplates for $399.95 each (PN SD8060AGP). That's a great deal. With 64cc chambers, the compression drops slightly, but this might cost 1 percent power, if that. The additional airflow the Vortecs offer is worth a solid 30 hp over your existing 416 heads and perhaps more.

The next option is, as you mentioned, the Edelbrock Performer RPM aluminum heads (PN 60999). These heads tend to be overlooked because they've been on the market for a few years, but they deliver excellent airflow combined with a relatively small port area that enhances torque. You can expect to make a solid 50 hp over your stock iron heads with these Edelbrocks, not to mention the extra benefit of a weight savings. The heads sell at Summit Racing for $499.50 each. The advantage of aluminum heads is that if damage ever occurs, aluminum is much easier to repair than iron.

We're about to test a set of Dart's new Platinum-series iron small-block heads that are the first of a new series of heads using Dart's new wet-flow technology. What we've seen on a 215cc head on the dry-flow bench is impressive, and we're going to test these heads against Dart's original Iron Eagle series, which was a pretty good head a few years ago. These heads may be a bit big in port cross-section for a 350 engine, but they sure look killer on the flow bench and promise to make even more power on the engine. These are the heads we used on the big-cammed 355 used in this month's test on E85. Dart does make a 200cc Platinum head that is pretty good. The part number for a 64cc iron casting with 1.437-inch-diameter valvesprings is 10311112P and sells out of Summit Racing's catalog for $537.95.

Now let's address your cam question. First, let's spec your existing GMPP LT4 Hot cam. This is a hydraulic roller camshaft (PN 12480002) with 218/228 degrees of duration at 0.050 inch tappet lift with 0.492 inch lift when used with a 1.5 rocker-arm ratio. The cam also has a lobe separation angle of 112 degrees. These are very close to the specs you asked about, so we're not quite sure why you'd want to change the cam. And if you did install a cam with the slightly shorter specs you mentioned, that would only kill a little bit of horsepower. Frankly, in our opinion, your existing Hot cam is a perfect match for all three of the heads we mentioned, and especially for the Vortec iron heads, since those heads are a bit limited on the exhaust-flow side. The Hot cam's longer exhaust duration will help scavenge the cylinder better, improving top-end power. We'd recommend buying a set of heads; keep the cam and have fun making a bunch more power. But that's just us.

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