Also, I've noticed the temp on this combo is very warm: 232 degrees. I have tried new T-stats, both 160- and 180-degree models, a new water pump (although not an aftermarket or electric), and a new aluminum radiator-one 14-inch electric fan pulling with a trans cooler on the outer side of the radiator and a 12-inch electric fan pushing from outside the radiator. I've tried stainless steel upper and lower hoses (advertised better heat dissipation), but it still runs warm. I didn't trust the 1989 gauge, so I have been using a laser-pointed heat gun and getting readings off the thermostat cover and upper hose of 232 to 235 degrees. I'm wondering if the port-and-polish job did anything. It was done by a local but reputable engine builder. Any other advice would be appreciated.
Jeff Smith: The difficulty you've run into, Gary, is the wider Crane Energizer rockers. The Crane Energizer rockers are an earlier design that used a larger aluminum body. These rockers worked well on the first-design small-block heads with a perimeter valve-cover bolt arrangement. But with the Vortec-style center-bolt valve covers, internal clearance becomes an issue. Crane has addressed this by building narrow-body Crane Gold Race rocker arms that are aptly named. These will clear the stock-type rocker-cover bolt stands, although we have run into very minor clearance problems even with these newer, narrow-body rockers. We've used these rockers on the stock valve covers without the rockers hitting the top of the covers, so this is one solution, although it's expensive.
Electric fans work well, but for ultimate slow-speed cooling, a shroud assembly that will pull air from the entire radiator is the only way to go. Most shrouds also include small rubber flaps that will vent pressure at high speed to increase airflow at freeway speeds.
Another option is to try a taller aluminum valve cover. Trans-Dapt offers both short (PN 6992, $103.88) and tall cast-aluminum covers for the Vortec heads. The taller cover (PN 6986, $115.88 from summitracing.com) will clear the valvetrain but still might offer some interference with your wider rockers. We talked with the company's tech department, and it's possible to thin the cast-in stands slightly with a die grinder. But before you start grinding, measure the distance between the rockers where the stand sits and then measure the actual thickness of the stand. This should tell you whether you have enough material to work with. Remember, the stand is hollow, so you can only grind so far. Moroso also sells a center-bolt valve cover for these engines with a machined stand for extra rocker clearance. Perhaps if you called Moroso's tech department, someone could measure the thickness of the stand and you could compare that with what you need to clear your rockers. This is a die-cast rocker cover under PN 68030 ($146.88 at summitracing.com) that also includes eight stainless steel button-head fasteners and nylon washers. Moroso also offers fabricated aluminum valve covers PN 68025 ($349.95) that are cool, but obviously pricey.
As for your overheating problems, you don't mention when this happens. We'll assume the temperature rises during low-speed operation, that's where most cooling-system difficulties occur. Generally, this can be traced to a lack of water circulation due to an underdriven pulley ratio or to insufficient airflow. You mention that you have two electric fans on the radiator and a new aluminum radiator. While this sounds sufficient, you should consider using some kind of shroud in addition to the electric fans. For example, most of Flex-a-lite's electric fans now come with a built-in fan shroud. The shroud pulls air from the entire radiator rather than just the circumference of the fan. This can make a big difference in cooling-system efficiency, since perhaps as much as one-third of your radiator is not being used efficiently.
Another couple of things to try are not necessarily part of the cooling system. The first thing is to make sure the engine has sufficient ignition timing. Set the initial timing at around 10 to 12 degrees and then check the total advance curve. You can do this in the car with the dial-back timing light and a tach. The total timing (without vacuum advance) should be around 36 degrees, and it should be fully advanced by 2,600 rpm. More timing improves low-speed cooling by beginning combustion sooner. Another trick you might try is to add vacuum advance at idle with straight manifold vacuum. That can help. Also, pay close attention to air/fuel ratios. A very rich mixture can make an engine run hot. It sounds ironic, but leaning out the idle mixture can contribute to making the car run cooler.