Roller lifters on mechanical cam?
- Thread starter Cazbah362
- Start date
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twayne24365
Well-Known Member
Thats interesting, i look forward to hering this one, but idk, a flat tappets lobes are much more pointy compared to a rollers egg shaped lobe, dont know how that would work out or if it would pose a problem
You'll screw everything up and break stuff.
Roller cams are flat across the lobe where as a Hyd. Or solidified cam have a taper or bevel on them to rotate the lifter. Since roller lifters are NOT to rotate, this will cause a problem.
Will it run? Yes
Will it fail? Yes!
Will it destroy the engine. In grand fashion!
Will I need to remachine it. Yes! EVERYTHING will need to be redone.
Instead of a $1500 or so in parts for the proper set up you will be into a new engine, every last part for the tune of "Lots-O-Money!"
A roller valve train is expensive. Rebuilding/building an engine is a huge expense by compare.
Roller cams are flat across the lobe where as a Hyd. Or solidified cam have a taper or bevel on them to rotate the lifter. Since roller lifters are NOT to rotate, this will cause a problem.
Will it run? Yes
Will it fail? Yes!
Will it destroy the engine. In grand fashion!
Will I need to remachine it. Yes! EVERYTHING will need to be redone.
Instead of a $1500 or so in parts for the proper set up you will be into a new engine, every last part for the tune of "Lots-O-Money!"
A roller valve train is expensive. Rebuilding/building an engine is a huge expense by compare.
Really no need to go any further. lol
Then there are some dumbass big block guys out there. Jes sayin.
RR - Worlds full of them.
I just found the idea perplexing, you have people shimming oil pumps, putting mechanical on hydraulic, etc... Each to his/her own.
The guy I spoke with swears he gets performance out of the rollers, however I am with you guys and I call BS - Was looking for someone who has actually done this and get there insight. Not that I would do it, just someone has had to have tried it.
I just found the idea perplexing, you have people shimming oil pumps, putting mechanical on hydraulic, etc... Each to his/her own.
The guy I spoke with swears he gets performance out of the rollers, however I am with you guys and I call BS - Was looking for someone who has actually done this and get there insight. Not that I would do it, just someone has had to have tried it.
MikeStahl
Well-Known Member
That's one way to eliminate the competition....!!!!!!!
CultClassik
Well-Known Member
Maybe there was a misunderstanding. Did they mean mechanical as in solid roller vs. hydraulic roller?
If they are talking mechanical flat tappet with roller lifters then yes, that's a bad idea!
If they are talking mechanical flat tappet with roller lifters then yes, that's a bad idea!
Another thing to point out why it should not be done is:
The roller lifters are capable of faster lifts and longer max open times. Using a flat tappet hydraulic cam doesn't have these features and therefore defeats the some of the benefits of running a roller tappet in the first place....
The roller lifters are capable of faster lifts and longer max open times. Using a flat tappet hydraulic cam doesn't have these features and therefore defeats the some of the benefits of running a roller tappet in the first place....
LJ67barracuda340
Well-Known Member
Not for very long,,,did they mention that?
Here is the reason it cannot be done successfully. Roller lobes and flat tappet lobes are entirely different in profile. If you put a roller lifter on a flat tappet cam, when the lobe's peak comes around, it will cause the lifter to fly over the peak of the lobe. The lifter will literally leave the lobe's surface.
Conversely, with a roller lobe, the lifter rolls completely over the surface of the lobe's peak. The flat tappet cam lobe has a much greater peak angle. The roller cam lobe is a much more gentle curve so that the roller lifter stays put.
Conversely, with a roller lobe, the lifter rolls completely over the surface of the lobe's peak. The flat tappet cam lobe has a much greater peak angle. The roller cam lobe is a much more gentle curve so that the roller lifter stays put.
Gentlemen,
He was very clear, MP 528 with roller lifters.
RR, Rumble and others who posted constructive insight, I agree, I thought it was odd too, I don't necessarily see it not working. Only constructive part I could see is the parasitic drag from the roller part.
I could see the ramps/peaks kicking that off at higher rpm and there being issues, however with a sturdy valve spring, could minimize it.
But really - not something I plan on doing, was just a science project question. I figured someone may have practical knowledge and elaborate for us.
My thoughts
He was very clear, MP 528 with roller lifters.
RR, Rumble and others who posted constructive insight, I agree, I thought it was odd too, I don't necessarily see it not working. Only constructive part I could see is the parasitic drag from the roller part.
I could see the ramps/peaks kicking that off at higher rpm and there being issues, however with a sturdy valve spring, could minimize it.
But really - not something I plan on doing, was just a science project question. I figured someone may have practical knowledge and elaborate for us.
My thoughts
Yes, yes, and yes. Here's a diagram of a hydraulic or solid cam design. The roller lobes are flat and the rollers are also. This design with the tapered lobe and the crowned lifter combined with the offset causes the lifter to rotate so it doesn't eat the cam lobe up. I wouldn't want my roller lifters trying to follow a tapered offset lobe and expect it to last. tmm
(The cam lobe is machined with a slight taper that mates with a crowned tappet face. The camshaft lobe does not meet the tappet in the center of its face)
.......................I will go out on a limb here and say there's no way in hell it would even run more than a few seconds if it did at all......and have a catastrophic failure.......just remember some ppl r dam good story tellers......kim.......
Puzackly.
moper
Well-Known Member
I actually did this. Back when I was 17. Short answer... Don't. Just don't.
In my case I used factory rollers and dogbones (this was in the 80s - they were brand new technology in stock engines). I did not, however use the spider to retain the dogbones. It ran great, bur a short time. A few days of daily driving and beating the tar out of it, which was my driving style back then. When I took it all apart the rollers that didn't spin when the dogbones popped off were eating through the lobes. The ones that did spin wiped them and the roller wheels off too. It did run before I took it apart.
Just don't.
In my case I used factory rollers and dogbones (this was in the 80s - they were brand new technology in stock engines). I did not, however use the spider to retain the dogbones. It ran great, bur a short time. A few days of daily driving and beating the tar out of it, which was my driving style back then. When I took it all apart the rollers that didn't spin when the dogbones popped off were eating through the lobes. The ones that did spin wiped them and the roller wheels off too. It did run before I took it apart.
Just don't.
Yup....Reminds me of one of my favorite conversations I had with a Mustang guy in the staging lanes years ago:
Me "Nice blower" referring to his roots style 671 blower protruding from the hood.
Him " "Its not a blower, its a super charger"...looking at me like I was some sort of car illiterate idiot, LOL!
Me (trying to change the subject and contain my laughter) "Well, it sounds healthy, what size cam you have in it?"
Him "It's 360 degrees duration"......#-o....
Me "Eh, that can't be right...it wouldn't run"
Him "No, that's what the guy told me that built the car"
Me "Well...((snicker, snicker))...isn't that somethin". I had to leave because I could not keep the laughter in any longer, and this guy CLEARLY didn't know anything about his car.
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