"........Motor seems happiest at 2800 to 3000 rpm.
My my we are getting soft in our old age. A HiPo 289 will run very happily at 4,000 to 4,500 rpm all day long, and get up the next day and do it again. Over and over. These cars were driven coast to coast like that without wearing out anything, without hurting anything, and lasting decades before needing any internal motor attention.
YOU may not be used to driving at these rpm levels hour after hour because modern cars have lulled today's drivers i Tom thinking a motor should barely turn over at highway speeds (thanks to emmision / pollution constraints). And nothing wrong with that, I like to breathe as much as anyone. But don't think the motor in the Shelby's can't take a little exercise. The cars haven't gotten soft. You can drive it to the limit for the rest of your life and it will still be ready for more long after you are 6 feet under.
Z
PS. If you add a vintage Paxton, a 3.00:1 rear gearing , and a 2.90 1st gear works fine. But at stock horsepower levels, I would not go any higher than 3.25:1 , with the 3.50:1 being a good all-round choice, and the same std. gear found in the stock 289 K code cars.
What about a 302 roller rocker out of an 89 Mustang? I get concerned the engine will blow up at 4,000 rpm for extended periods at 70 mph. But I like the sound and fury and can live with it just fine so long as it holds together. 3.50 rear incidentally. I really don't want to go to a five speed otherwise when I have a Toploader four with Richmond gears out of Klutt's race car. Don't care about gas mileage. Just means I buy more gas and eat less food. Win win.
Happy motoring,
Richard E.
Those roller rocker arms are bolted down with 5/16" bolts. These days I would say that 7/16" studs are preferred but 3/8" studs are acceptable.
l'd consider the 5/16" have a red line at 6,000 rpm. Where they fail depends on what valve spring pressures you are running.
I do not think that roller rocker arms were permitted by the rules back in the day. Valve train failures were mostly the valve keepers or the valve springs letting go and the valve getting sucked into the cylinder.
Valve spring technology of the day limited rpms pretty much to a strict 7,000 rpm limit.
In all these years I've only had one valve train failure and that was the pushrods in my Pantera. They were Crane "Ultra" push rods and the tips on about 6 of them all failed at once. The tips are welded on with a little pinch weld and they had been so hardened by Crane that the tubes cracked and shattered, letting the tips come off.
It's better to have them bend. That way you get no shrapnel in the top of the engine to clean out.
Regardless of what anyone tells you, all rocker rollers do is eliminate (or close to it) the scuffing on the bottom of a standard rocker arm, the valve tip, and the oblonging of the valve guide because of the pushing the rocker arm is doing sideways.
Picking up HP is really BS. Reducing oil temp is from reducing the said friction.