Going back to the reversion issues at lower RPM's, I gotta ask if 'more power everywhere' means more torque below 2500 RPM..... I am a bit skeptical (but sure don't know it all) and still think it is a trade-off for what you want to do, and the lobe type you want to run. Let's face it: If you are in a low cost mode and all you can afford is a lowest cost flat tappet cam and cheap springs, you're just gonna have certain lobes to pick from and if you want to emphasize real low RPM torque, then you are limited on your options. I don't see it as particularly 'wrong'.....
I don't know the Vizard tests and what they were optimized for...It's a pretty interesting topic to me. FWIW.... I have been on the shorter duration/higher lift page for a long, long time.
BTW, not of this applies not the OP... this is just the usual internet tangent LOL
2500 is about as low as I'll go on a dyno pull. No reason to go lower. I'm not one to fret about what goes on at those RPM's. It just isn't worth it. It's like the head Porter who worries about flow under about .200 lift (depending on application). I look at those numbers, but don't fall on my grinder if I loose some flow there, for the right reasons.
As for reversion, we have to discuss which reversion are we talking about?
IMO, there is very little reversion from the LSA being narrow. I have seen it. It's pretty rare. You'll know when you are getting it. It shows in the bowls. You'll see where the exhaust is going right across the seats and into the intake port.
Most of the time, that's from a poor valve job. Like when you use a radius valve job on the intake side. If you do that, you need to change the cam timing. That radius on the intake seat promotes reversion.
Reversion that kills power, makes things dirty and is a general pain in the *** is intake valve closing. That's a killer.
Did a 377 inch SBC in 1988. Had a Crane inverse roller cam, which at that time was the bees knees.
At idle, you could see the fuel stand off above the injectors at idle. If everyone had a phone back then, like today, people would be amazed. I'm sure if you look you can find something similar on YouTube today.
I noticed two things when the cam showed up (I didn't pick it). It was on a 111 LSA and the intake looked like it close too late. Wish I could remember the rest of it.
Luckily, a very close friend of the engines owner called Isky and Ron sent his idea of what should be used. It had more duration and a 108 LSA.
After 6 pulls on the dyno, the valve springs were toast. So we spent the rest of that day changing springs. Luckily, we had a set of spares of those too.
The Isky went in. No fuel stand off. It was cleaner at idle. I can't remember the barrel valve leak numbers now, but the Crane needed 3-4% more leak than the Isky did. After 20ish pulls we ended up at 645 HP at 7000ish, which for 1988 was pretty damn righteous.
That car eventually went in the 8's.
I say reversion is much more an issue of intake closing than LSA. You can also open the intake too soon...but that another discussion.
