89 360

The problem with the magnum heads is that they oil through the pushrods, and not the block. As for the 360 haveing enough stroke for the bigger valves and that you wouldn't see the difference, if this was the case then they should have put them in from the factory as machining would have been cheaper. Once again the cam that is going to be used is more than likely going to be a low lift, a street/strip type. The bigger valve loses velocity and flow at low lifts this is why the factory used a smaller valve in the cars when produced.
I/we have tried this on a 318 with 360 heads and the 360 heads were done the same as the 318 heads, bowl blended and gasket matched, the 318s were gasket matched to the 360 gaskets. The 360 heads were 40HP loss on the 318 and when we went back to the 318 heads the car picked right up. Even though the 318 had 1.78 intake valves and the 360 had 1.88 valves. The port on the 360 cc'ed at 150 and the 318 cc'ed at 132, the air flow on the 360 was 234 cfms and the 318 was 213 cfms, the problem came from the velocity as the smaller valve and the smaller port was more efficient than the bigger one. Both air flows were at .400 because most cams for the street aren't much bigger than this, and .500 is more suited for racing applications. Here are some #s that I have come up with on 2 very well ported 360 heads.


lift 2.02 1.88
.100 94 96
.200 177 185
.300 223 229
.400 251 248
.500 287 283
.600 287 285
.700 285 281

The 2.02 has a efficentcy rating of 59.1% and the 1.88 has a rating of 68.4% the difference comes because of the valve size. As you can see there isn't much difference in the air flows, but you have to look at the low lift #s as this is where most of the valve action happens. Also with the smaller valve the velocity rating will be much higher due to the valve size. If you can get/make the same air flow as a bigger valve then the smaller valve will make more power and be faster, and more fuel efficent.
The 2.02 head has a 167cc runner and the 1.88 has a 165cc runner, so the work in the ports is the same just the difference in the valve size to make the port difference.

BJR Racing