do those hi intensity lifters realy work like they say, reducing lift and duration at lower rpms?

 

Yes they do. A motor with these lifters will have more idle vacuum
and low rpm response then a normal lifter.

Comp has these type of lifter available in 3 different "bleed rates"
The faster the Bleed rate, the more the valve lift profile is reduced at low rpm. Te only drawback is they have increased noise at idle somewhat like a solid lifter cam.

 

are these like Rhodes Lifters?

 

$1-2.68,

Crane Hi-Intensity lifters are EXACTLY like Rhodes lifters. It's rumored that Benz and a couple of their Axis partners are planning to use high-bleed lifters to make their little engines more environmentally friendly and still be able to make some power.

It seems that everything that is old is new again...

 

if they reduce cam lift untill about 3000 would i get better gas mileage at cruising speeds? i'm thinking of going to a .462/ .469 lift 218/ 224 duration comp cam to get some good upper rpm power, but i don't want to lose a ton of mileage and low end trq. that is the cam that comp recomended without hi intensity lifters, would i be able to go to a little more cam than that with hi intesity lifters?

 

I have not seen high-bleed lifter in a roller configuration, so if you find them, please let us know.

 

Aftermarket roller ramps are steep enough that a fast-bleed lifter wouldn't have much effect... add .060" of lash at low speeds, all you do is make more noise, the valve still snaps open more or less instantaneously. And stock rollers, which have the same lazy profiles they put on their flat-tappet designs, are already so weenie that no one needs fast bleed lifters on them.

That's the idea, that you can run one step larger of a cam without paying the price in the form of one step poorer low-speed behavior. They work by decreasing the effective duration of the cam, since with a gentle ramp at the start of valve action, adding some lash takes out many degrees of duration. But with modern high-intensity cams, they have less effect, because the ramp is so steep. Think about some really lazy cam with too much duration, like the GM "151" for instance, that kind of lifter would have a dramatic effect; but if the ramp was not a ramp at all, but was rather a brick wall, they would have no effect whatsoever, except to make more ticking noise.

Personally I have never liked that kind of lifter. I built a few motors for people who wanted me to use them when they first came out back around '80 (Rhoads) and every one of them ended up getting rid of them. Seems like Jester from the carb board recently went through exactly that not too long ago... put them in, didn't like them, took them back out.

 

is the comp #XE12-238-2 262 is a flat tappet cam. thats what comp recomended and i included that it would be a flat tappet cam. they also come in kits with flat tappet lifters, but i'l probably use the hi intensity lifters. i'm realy not worried about noise if it means keeping some low end trq or go to a 268.