[Keithc8]

When dealing in the real world most people are concerned about price and what it will take to make the headers and sidepipes that come with the car work. If they are wanting to build the baddest all out engine based on a 351 Winsdor engine the CHI heads as well as the Blue Thunder 4.30 or the Ford racing D3 are all options but not real pratical for a street engine. Most all of the engines on the Engine Master compition would not make it 1000 miles juch less 10,000 miles because of the light parts, low tension rings, compression and ever other little HP robbing trick there is to do. They are not real word street engines that you would put in a Cobra.
The reason for the bigger heads on the 427 Chevy is the basic design of the engine with a 4.250 bore which will accept larger valves easier and it has a large runner volume. These were designed to ne race engines and not street engines. If you look at the 454 street engines, they had a oval port small valve head for torque with a smaller runner volume. Just depends on where and how you want to make the power. I see this problem a lot with guys that have jet boats and install big heads and camshaft with a tunnel ram intake and it runs like crap. The jet will only let the engine go up to about 5000 rpms and they have way to much head, camshaft and intake. I have taken these guys and made all of this stuff smaller and they have ran much better in the boat.
If we were not dealing with street engines and could run the compression up to 14 to 1 and turn the engine to 8000 all the time the bigger heads would work great. There is a place for all of the heads on the market when used in the right application. Good luck, Keith Craft