318 Head Opinions

The thing that we have found is that when you have a large port head, such as the X or J heads or any 340/360. That the 318 just can't utilize the port to it's advantage as go's for the valve size. I know I'm going to catch some slack on this but, we did this years ago, also as this was the ticket and none of us were the wiser. But about 10 years ago we tried a set of 302's and we also used the 1.88 valves, and thought that bigger was better with the small chamber head, but boy did we get a rude awakeing. The heads actually ran a bit slower and the bottom end (starting line) was where we did the suffering at. It was due to the loss of low end torque and later found out that the valve size was too large and slowed the velocity down in the port. So about 4 years ago we went back to the drawing board and used the same casting heads so not to have to repair the ones that were on the engine and to give a good comparision, and utilized a stock sized valve on the intake side with the same modifications done as the 1.88 valved heads had. The torque and performance was marginally different to the tune of 30 ft.lbs. and 40 more HP, and this was useing a .480 280 comp cams grind which is very close to what moper has stated(228 @ .050). But because the fact that the heads have more velocity in them and are more efficent for the 318 bore they work better on the engine. Thus allowing you to get away with more cam as the 228 @ .050/280 cam sounds fairly stock. We just finished a 318 engine and ran a .501/292 comp cam in it as we already had the cam and we knew that the other cam didn't have much sound and wanted more. The engine is a bone stock rebuild in the short block with a mildly ported set of heads (318's) with stock valve sizes, the engine idles at 800-1,000 rpm's. Yes we have a stall converter in the car but he (Valiantmike) has a 4 spd. and this cam is 244 @ .050 and is a straight pattern cam. This is why I like the XE284 as it has a 106/114 centerlines and helps to build cylinder pressure by keeping the overlap lower. We are useing this cam in a lower compression 360 engine, I know it has more stroke but this cam sounds very tame much like the 228 @ .050 cam in the 318. Being that it was so tame in the larger engine with larger heads we figured that the smaller heads would tame it even more, which it did when installed in the 318 with smaller port 302 heads. This is partially why the engine idles at 800-1,000 rpm's with the old style 292 cam which is 244 @ .050. Port size and velocity has alot to do with what cam is used in a engine more so than airflow and valve size. Obviously if we had the 340/360 heads on the engine the engine would be a dog in the low end as torque and hp would be down, and the need for low gears and a higher stall converter would be needed with the same cam. Also smaller ports that have higher velocity will use less fuel and be more efficent and make more power. With the 340/360 heads I was buring about 1/2 gal. per run and now with the 318 heads I might be burning a Qt. 9 runs was just under 4 gals. of fuel in the 1/8 mile.
Sorry for being so winded but I wanted to give a real world account of what small changes will do and the reasoning behind it and the change it made in performance. I hope this helps everyone to have a better understanding that bigger isn't always better in the case of the 318's, but the right parts in the right places will make bigger gains with less $$$$ out of the pocket.