Another difficulty with running this much compression is the 3.08 gears, which put more load on the motor. If you were running a set of 3.42 gears with the TH700-R4 and those tall tires, that would put less load on the engine and perhaps help keep it out of detonation. The other variable is that you live in Texas, where it gets mighty hot in the summer. We'd stick with the 487 heads.
Just adding a 30-degree back-cut (arrows) to both the intake and exhaust valve will really improve flow, especially at the low- and midlift levels, where it can really help power.
We also have a couple of suggestions as you rebuild those 487 heads. Think about adding larger 2.02/1.60-inch valves, especially if you have to buy new valves since the cost difference is minimal. The larger valves will help flow. Either way, be sure to ask the machine shop to add a 30-degree back-cut to both the intake and exhaust valves. This little technique helps flow across the board on almost all small-block Chevy heads, especially on the exhaust side. This will help torque and top-end horsepower, and the cost for the machining operation is cheap. If you want to try some simple bowl work, just radius the sharp edge underneath the valve seat on both the intake and exhaust. This will help flow-but don't get carried away or you could ruin an otherwise decent-flowing head. Do these little tricks, and that'll wake up your small-block.
Ancient Tech Tip Rehashed Here for Your Convenience Want to know which way your distributor rotates? Just point right at the nipple of the vacuum advance and you'll point the way. In this case, it's counterclockwise.
The Guide To Seals
John Langner, somewhere in Wisconsin: After 30 years of being a backyard mechanic, I finally decided at 46 years of age to build an engine right. I hired Ken Brewer at Pacific Performance Racing to build a Pontiac 455 that would give me a solid 500 hp. He did just that. The engine came in at 505 hp and 558 lb-ft of torque. Not sparing any expense, I went with Edelbrock aluminum heads.
After driving the car all last summer and not experiencing a single problem, I wanted to dress up the engine compartment by switching to a polished intake. I had to wait three days for the gaskets I wanted, so one night out of boredom I shone a flashlight down the intake ports only to find that all eight valve stems looked like they had 100,000 miles on them. The valves that were completely closed actually had a small puddle of oil on them. These heads were preassembled and installed out of the box. They are the 87cc, chambered heads, and the cam is under the maximum lift allowed by Edelbrock. The engine runs at 175 degrees F and has never been above 190 degrees. I have about 4,000 miles on the engine and change the oil every 800 to 1,000 miles with Kendall 10W-40.
I contacted Edelbrock and spoke with two separate technicians. They are not aware of anyone else with this problem. I have not taken them apart yet, but when I shine a light through the springs, none of them seems to be broken or out of place. I do not have the notorious puff of blue smoke that normally comes with bad seals, but I have been a reader of Car Craft long enough to know this isn't always the case. Also, although the color of my spark plugs is almost perfect, I've always had oil on the threads when I take them out to inspect, and now I suspect it's been the seals all along.
If the seals aren't defective, why did this happen? If I change them with the same style that's in them now, who's to say it won't happen this summer? If there was a problem during assembly, what are the chances that all 16 were damaged? (I'm assuming the exhaust seals are bad, too.) Do you have a recommendation as to what brand or style of valveguide seal I should use? I was running open breathers on both valve covers instead of a PCV valve. I have since installed a system with check valves. Even if I were getting some vacuum back through the breathers, would this actually cause this?