Roller vs. Flat-Tappet Cams! - Engine Masters Ep. 16 Motor Trend Channel

[plovett]

 Every OEM went that way despite the expense multiplied by millions of vehicles.  Probably not an accident.

The OEM's went that way because even a small mpg gain is worth a lot when you're trying to meet CAFE standards, and the added reliability.   Also, the costs are mitigated when it's spread out over millions of vehicles.  It wasn't primarily for performance with most of the little OEM cams, in my opinion.

paulie

[plovett]

I'm more of a visual guy so I found this explanation on Isky's web site beneficial. If I have to use a flat tappet (for rules) how could a lifter be configured to be used on steeper roller style ramps?
Would the roller profile make more hp than the flat tappet at the same lift (lets say it's limited to .525)

Yes, that helps.  I think the blue line can be more vertical, that is diverge from the red line, at the very start.  That would be the flat tappet getting out of the gate faster, or at least having potential to do so. 

Now imagine those curves spread out horizontally.  The red curve would have even more area under it compared to the blue curve.  That would be a larger duration cam.  If you do the opposite and squeeze the curves horizontally inward, there were be less difference in area. That would be a smaller duration cam.

This is just geometry.  It has nothing to do with rpm.  It doesn't matter if you look at duration at the valve or at the cam, because the two are directly related, and caused by what happens at the cam.  All that matters is how much linear motion you can get per degree of rotational motion.  Flat tappets and roller tappets have different constraints.  One is acceleration and one is velocity.  Both of those are affected by time.   Sorry guys that I'm not able to articulate better.  I think maybe if we could overlay many different flat vs. roller profiles of varying durations it would be more clear. 

JMO,

paulie

[Heo]

Packard had Roller "cam" in the 20s on the flathead engines.
Think about it as a upside down OHC, they had a rocker arm
hinged on one side with a roller in the ""middle and the valve on
the other end. If the main goal was performance or reliability
i dont know. But i guess both to get 90 reliable hp out of a 348
This thing about adjusting the valves on a  solid lifter cam.
I call it a myth i have never had a solid cam that i had to adjust
the valves regulary on. The european cars started to get hydraulic lifters
in the 90s and no one here adjusted there valvelash several times a year
before that.
And thats on daily drivers that run tens of thousand of miles each year
If you have to do that you have something wrong. Loose adjuster, bent pushrod etc etc

[My427stang]

All good discussion.  In the end though, it goes back to valve events.  The area "under the curve" discussion leads to a change in cam profile, so you really cannot compare two cams with different valve events if you want to see the difference in power from a lifter design

My opinion is:
1 - The justification for going roller, hyd or solid, due to fear of cam break in is valid, and if the insurance is worth the money for you, go for it.
2 - When picking a camshaft, if the valve events you want require one lifter design or another, it also answers your question. 

In the end though, do not fear cam "wear" with either design, if it wore that fast, something would be seriously wrong

[scott foxwell]

All good discussion.  In the end though, it goes back to valve events.  The area "under the curve" discussion leads to a change in cam profile, so you really cannot compare two cams with different valve events if you want to see the difference in power from a lifter design

My opinion is:
1 - The justification for going roller, hyd or solid, due to fear of cam break in is valid, and if the insurance is worth the money for you, go for it.
2 - When picking a camshaft, if the valve events you want require one lifter design or another, it also answers your question. 

In the end though, do not fear cam "wear" with either design, if it wore that fast, something would be seriously wrong

For me, the fear of a FT failure goes past break in. Over the years we've seen plenty of examples of guys following perfect break in procedures including new break in oils, only to end up having a lobe failure. I think if you're getting a custom cam ground you have a much better chance of success, but even then, lifters these days are a crap shoot. As few miles as many of these engines get driven, the problem may not show it's ugly head for years. The 390 in my Fairlane was rebuilt 7 yrs ago with a Comp hft cam and lifters but probably only has a couple thousand miles on it. I was going to pull the engine to clean up the engine compartment but I also felt like there were a couple cylinders "not quite right", so I figured I'd pull the cam (my first suspicion) and I was right. Two lobes were on their way out. Worn less than .010 but you could see the wear on the lobe and you could definitely measure it. I don't know what the break in procedure was on that particular engine but these days, with ANY ft cam, the potential always exists. Again, JMHO.

[Falcon67]

I can offer some specific in regards to Brent's comments.  We ran a F238 solid in the 351C in the Mustang.  It ate a lobe for some reason and that was the end of that.  I replaced it with a Howards hydro roller and cam with close to the same specs. 

Crane - @ .050 238/248, adv duration 300/310, LSA 108, lift .554/.577
Howards - @.050 233/241 adv duration 286/294, LSA 110, lift .594/.611

Car ran same MPH, ET, 60', etc after the swap. 

Over the years we've seen plenty of examples of guys following perfect break in procedures including new break in oils, only to end up having a lobe failure.

The F238 ran in my engine 2 years, no problems.  The lifters were Isky EDM lifters that use a oil hole in the face to help lube the interface between cam and lifter.  Good parts.  Pulled it out, stored it a year in plastic with the lifters numbered and stored, pushrods - washed, oiled, carefully packed, etc.  Installed in the other 351C, clean room install, break in lube used just in case, short run in, same adjustments, etc.  All good, take it to the track - car lost ET and MPH on the 5th pass.  Exhaust lobe on #8 lost about .200 lift and was mushrooming the lifter.   

[scott foxwell]

I can offer some specific in regards to Brent's comments.  We ran a F238 solid in the 351C in the Mustang.  It ate a lobe for some reason and that was the end of that.  I replaced it with a Howards hydro roller and cam with close to the same specs. 

Crane - @ .050 238/248, adv duration 300/310, LSA 108, lift .554/.577
Howards - @.050 233/241 adv duration 286/294, LSA 110, lift .594/.611

Car ran same MPH, ET, 60', etc after the swap. 

Over the years we've seen plenty of examples of guys following perfect break in procedures including new break in oils, only to end up having a lobe failure.

The F238 ran in my engine 2 years, no problems.  The lifters were Isky EDM lifters that use a oil hole in the face to help lube the interface between cam and lifter.  Good parts.  Pulled it out, stored it a year in plastic with the lifters numbered and stored, pushrods - washed, oiled, carefully packed, etc.  Installed in the other 351C, clean room install, break in lube used just in case, short run in, same adjustments, etc.  All good, take it to the track - car lost ET and MPH on the 5th pass.  Exhaust lobe on #8 lost about .200 lift and was mushrooming the lifter.   

That's not surprising. Once a cam breaks in in one block, it's hard to be sure another block's lifters are going to have the exact same orientation. Fords usually seem to be pretty good but you sure won't get away with that in a BB Chev.

[blykins]

When I do a flat tappet cam, I always have them ground with a little more lobe taper than usual. 

[ACHiPo]

At the risk of asking a stupid question, how do flat hydraulic lifters compare to solid flat tappets or hydraulic roller lifters?  I originally wanted hydraulic roller lifters (seems to be the popular thing to do) in a mild 482 FE side-oiler (BBM block), but my engine builder claims to have had a lot of issues with hydraulic rollers in FEs so he put in hydraulic flat tappets.

Here's my take.  In general hydraulic flat tappet cams are less "aggressive" than solid flat tappets and hydraulic rollers.  By aggressive I mean the steepness of the lobe, how fast the cam moves the pushrod up as the cam lobe turns.  I have to say in general because there are all sorts of cam grinds in each type of lifter.  There are some pretty aggressive hydraulic flat tappet grinds and there are some very mild solid lifter and hydraulic roller cam grinds. 

I don't know what issues your engine builder had with hydraulic rollers, but they're used all the time.  Maybe he had valve control problems at higher rpm?  If you're under 6000 rpm it doesn't seem to be a problem.

My opinion is that on a big engine like a 482 you're probably going to have a cam with a good amount of duration, even if it is a fairly mild build, just because of the cubic inches.  In that case I would think a hydraulic roller could make some significant gains over a hydraulic flat tappet.  The greater duration gives the roller cam more time to blast by the flat tappet and create more area under the curve.   It can hold the valve open further for longer, even if the 0.50" duration is similar.

JMO,

paulie

Thanks.  I tried to send you a couple PMs, but not sure if they went through.
Evan

[blykins]

I can offer some specific in regards to Brent's comments.  We ran a F238 solid in the 351C in the Mustang.  It ate a lobe for some reason and that was the end of that.  I replaced it with a Howards hydro roller and cam with close to the same specs. 

Crane - @ .050 238/248, adv duration 300/310, LSA 108, lift .554/.577
Howards - @.050 233/241 adv duration 286/294, LSA 110, lift .594/.611

Car ran same MPH, ET, 60', etc after the swap. 

Over the years we've seen plenty of examples of guys following perfect break in procedures including new break in oils, only to end up having a lobe failure.

The F238 ran in my engine 2 years, no problems.  The lifters were Isky EDM lifters that use a oil hole in the face to help lube the interface between cam and lifter.  Good parts.  Pulled it out, stored it a year in plastic with the lifters numbered and stored, pushrods - washed, oiled, carefully packed, etc.  Installed in the other 351C, clean room install, break in lube used just in case, short run in, same adjustments, etc.  All good, take it to the track - car lost ET and MPH on the 5th pass.  Exhaust lobe on #8 lost about .200 lift and was mushrooming the lifter.   

That's not surprising. Once a cam breaks in in one block, it's hard to be sure another block's lifters are going to have the exact same orientation. Fords usually seem to be pretty good but you sure won't get away with that in a BB Chev.

Yep, that's why the "cam break-in machines" don't always work. 

[Joe-JDC]

Lifters in today's market are not hardened correctly to match the camshafts being produced, or the camshafts being produced are not treated properly to be compatible with the lifters available.  Ted Eaton won the EMC in 2016, but his entry for 2017 lost the camshaft and lifters on initial break-in procedures.  The camshaft and three sets of lifters were sent to a well known camshaft grinder for preparation to use on his EMC entry.  I will not get into the whole problem of the issues, but the lifters were not the same hardness as the camshaft, and wrecked the build.  Suffice it to say, that a professional engine builder that builds winning engines suffered a camshaft and lifter loss due to improperly matched parts from the camshaft supplier.  That is reason enough to go roller camshafts for me in the future.  Joe-JDC 

[Falcon67]

LOL, can now close the thread    

I just made the decision that I'd rather sit and watch until I can afford the parts I think are the better parts rather than save a little and maybe end up not saving anything.  A comp solid flat cam/lifter kit at Summit us $231.  If it fails, you buy another.  So you're at $462 plus all the gaskets, etc required because you had to take it apart and clean the crud out, plus down time, pulling the motor back out, etc, etc - assuming nothing else got hurt.  Similar kit, similar specs solid roller is $907, hydro roller $876.  The potential savings can be easily negated.

[chilly460]

Another point is that, at least in my opinion, I would run a used roller cam without fear once it's checked out.  Same goes for the lifters.  So if a guy is willing to run used roller parts, he can get into the setup relatively cheaply.  Of course this isn't "apples to apples", but it's a legitimate point.  The used market for FE roller cams is so so, but you can literally find any used roller cam you want for a SBF so they'll become more available as more guys run them in FEs.  I bought two this year at the FERR. 

 

[Tommy-T]

OK, I was sitting on the sideline and watching the roller vs. flat discussion "roll" on. Wasn't going to comment BUT I'm just too dumb to shut up.
First of all, I've never had an FE flat tappet solid go flat. I know it happens...but not so far to me. I've run different brands, but most of my stuff has been regrinds. One regrind in particular, I've had in 3 different motors.
I ran a 308R in a 454 incher that I picked up on Ebay. I didn't know anything about running a solid roller cam on the street, but I learned. I bought some used lifters from a local circle track racer that was running a small block Ford. They were Comp lifters, and the link bar is the difference between FE and Windsor. Changed the bars, pushrods, valve springs, and slid in the cam...and started it up.
It ran great! Picked up 3 tenths at the track. Drove fine on the street. In fact, its mannerisms were about the same as the old flat tappet. Ran it for a year and all was great.
Then one day Mrs.-T and myself were running usual Saturday errands and my car made some "unfriendly" noises and quit running. Cranking didn't sound good.
Had 'er towed home. Pulled the valve covers and there were 3 Dove rockers busted on one side, and 4 on the other. Called a racer pal and he came over with a spring checker.
You've got 90 pounds seat pressure, Tommy. That's what beat-the-crap out'a your rockers. When you loose valve control with a roller all hell breaks loose.

SO, when you say the expense of a flat tappet compared to a roller goes away if you have one go flat, that is only partially true. I've had flat tappet cams go years and years with only annual lash adjustments.
But regular maintenance with a solid roller would probably go: valve springs every winter & new roller tappets every third year.
When you add in the real world wear factor of roller tappets on the street, it gets pretty expensive.

[blykins]

That would indeed be true with a healthy solid roller.  A street roller would go longer than your maintenance interval.  I’ve got guys who have been running the same solid roller cam, lifters, and valve springs for 4-5 years and one guy in particular with a 428 of mine that’s on year 10...

A hydraulic roller should go 100k miles.