If you copy FordSedan Devliery's 440 cfm triple carb 250 engine, cam, and head, you'll get well over 225 flywheel hp. Easy. But it was an 11:1 compression ratio engine. But if you want 9.5:1 compression, then you'll need 1.73:1 rockers to make up the loss
Croselys 200 makes 205 flywheel hp with one 500 cfm Holley 2-bbl, and its a mild 200.
So between the two, there is a clear issue where the log head requires a better kind of cam lift profile, and some work on the porting to suit. Then the valve lift can go up. Ford Australia instantly lifted the cams lift profile, and made sapce for the valves to creat lift. So its all about how many total dollars you spend to get a hp level you'd like.
The rocker and cam pacakge with a log hea will cost as much as the Classic Inlines head and its normal Clay smith cam.
Those 1.65:1 rockers and Clay Smith Cam suited the head, but the head gave the power. If you do more cam and rocker work, the log head can be made to shoot well over 225 hp in a 9.5:1 compression engine.
Its the lift profile, cam and rockers that you need to gell together. The FE designers were prevented putting all the FE smarts into the Small Six because of budget. The Windsor was a backward step for many years, the Cleveland a forward step. The Chevy LS 4.8/5.3/5.7/6.0/6.2 engines copied Fords wedge head development work, and new of what Honda and Fords 1970's partner ship work ment for the canted valve big block Chevy and Ford 335 and 385 engines. They found that the canted vale engines were like Hemis, and they made emissions harder to obtain, and made less power for a given compression ratio. The Windsors wedge head became the darling, and the rocker ratio issue took Ford years to correct becasue the engineers decided to look at CFI, 4BBL and Port EFI. They didn't even look at the rocker ratio on Windsors becasue of the money.
That was a bad move, but you can address that with a 250 six by thinking.
"If I want 1.7 to 1.85:1 rocker ratios, what is the least I have to spend to get it, and how much hp do I get, and compared to any other change. IS IT WORTH IT?"
The answer is yes, its worth it, but you have to look at the gains in a per dollar basis, but not let the money rule out your options.
Hp costs, but not that much if your not buying other stuff. At 500 thou lift, there is 165 to 185 cfm per intake port air flow hiding in a late model log head if you manifold the carbs properly.
You can only get that CFM by lifting the valves higher than 500 thou. The advantage of rocker arms with high lift rates is that you need the peak lift cfm to be gotten by a higher than 500 thou lift, and that the engine is at sub 500 thou lifts twice as many times as it is at maxiumum lift.
You gain power, but you gain torque eveywhere if the cam suits the application. The valve lifters on Fords are big dimaeter, and make a great lift curve, which the high ratio rockers love.
Roller rockers won't help you in power at Dyno Test one on day one, but after 50000 miles, your vlave guides will like properly designed roller tip rocker. The valve guides can over comethe need to roller tip rockers. If designed right, they will help durablity, BUT cHEVY PROVED THAT YOU DON'T HAVE TO HAVE ROLLER TIP ROCKERS .
In the same way, Non roller cam engines can make as much power as roller cam engines, but on a road engine, you can too easily wipe out a cam follower or lobe, and put metal fragments through your engine. NASCAR engines are state of the art in making a poor engine combo work, but they use 1.9:1 rocker ratios to do it.
Anyway, its your choice.
