Roller lifters= not a good idea w/stock cams

[SATAN]

I felt the need to repost this incase someone got a wild hair and decided to go pull a bunch of roller lifters out of a vh45. This is why NOT to do that. Again sorry to post this again, just trying to save people money and a headache. If you guys deem it necassary to delete it thats fine.

Ok, are you ready???? This is why roller lifters will not work with a cam not designed for them. And if they do work they wont work like they are supposed to. The duration will be way shorter. You will still have the same lift but not the same duration, not even close. This is what I was trying to explain last night on lack of sleep. BUT I drew a picture(by hand) and took a picture of that cause I'm a computer retard but the idea is the same.




You can see the difference in the lift with the cam at a 45 degree angle is 3/8" or .375" THATS A LOT! Granted my picture is just an example and not real cams but you get the idea. Also note where the contact point is on the roller vs. the stock lifter. On the roller it is slightly off to the right of the center line. On the stock lifter it is WAY off to the right. So with my picture with both cams at a 45 degree angle the difference in lift is .375"!

The picture is not PERFECT but its pretty fukcing close! Close enough to make my point.

[Maxmaxima91]

Well said..

[Jason84NA2T]

Wow, someone actually taking time to explain it to people. So kind of you...

[G-E]

actually no, the degreeing and duration will change, not the absolute lift

what you'd need is a larger lobe with a super long duration .... what your diagram is showing is how soon the lifter is set in motion by the cam, and it is clearly much later.... while advancing the cam could equalize the ramp up, it wouldn't help for the same reason on the falling side, your duration would be miniscule

[SATAN]

G-E wrote: actually no, the degreeing and duration will change, not the absolute lift

what you'd need is a larger lobe with a super long duration .... what your diagram is showing is how soon the lifter is set in motion by the cam, and it is clearly much later.... while advancing the cam could equalize the ramp up, it wouldn't help for the same reason on the falling side, your duration would be miniscule

Um, yeah thats pretty much what I said. the lift would not change. but AT 45 DEGREES the lift is much less with the roller lifter than the regular lifter(in other words, the duration). I think you just misunderstood what I was saying. You and I are saying the same thing.

I didnt want to go into advancing or retarding the cam because of the confusion that would be involved.

[G-E]

yea somehow I read that wrong... or I missed some words.... I'm tired....

it maybe could be done with a really agressive base diameter grind ... and longer solid/roller lifters

[homestar]

correct me if i'm wrong but wouldn't advancing the timing solve that problem?

[Jason84NA2T]

homestar wrote: correct me if i'm wrong but wouldn't advancing the timing solve that problem?

You need to consider both sides of the lobe though...

[FreeLanceBum]

It might be possible to go with a bigger cam, and the added duration will help, and the increased lift will help too.

[SATAN]

Right but that is why it would be a bad idea to go with roller lifters unless you had a cam designed for a roller. Yeah you would lose friction but you would most likley lose way more power because of lack of durration than you would gain from lack of parasitic loss.

Long story short, if you run a drop in cam wether it be stock or aftermarket, you would see way more benifit from it and the stock lifter than a roller lifter with the same cam.

For those wanting to advance the timing, what happens is now the valve is coming off of the cam even sooner. Either way you still have the same amount of durration to work with. Nothing you can do about that. Thats what Jason is getting at.

[GotFast?]

Another problem.

Everyone I have talked to recommended highly against attempting to regrind a flat tappet cam into a roller cam profile.

I have yet to email schneider to see what there opinion is on the subject.

Isky will make roller cams for the car. Whatever lift and duration you want....But its going to cost big $$$

[SATAN]

GotFast? wrote: Another problem.

Everyone I have talked to recommended highly against attempting to regrind a flat tappet cam into a roller cam profile.

I have yet to email schneider to see what there opinion is on the subject.

Isky will make roller cams for the car. Whatever lift and duration you want....But its going to cost big $$$

Yeah, I figured. I would guess at least 450-500 for the set. Or more.

[Steve88t]

That is why when you look at roller cams, they seem to be a much fatter cam lobe. Much more rounded vs a non-roller having a sharper peak.

[SATAN]

Steve88t wrote: That is why when you look at roller cams, they seem to be a much fatter cam lobe. Much more rounded vs a non-roller having a sharper peak.

Yup, just like what I was talking about in the other thread.

[StreetFighter]

Well... The whole point of having a roller valve train is the ability to have a much more agressive ramp on the cam lobe. A roller lifter can follow a lobe that ramps up almost immediately. You want the valves to open fast and close fast... as fast as possible. In an ideal setup, the valve would open to it's max lift immediately, stay there as long as needed, and close immediately. You would want the valve lift to look more like a square wave than a sin wave.