Roller cam vrs flat tappet

[Houle #382]

Thinking about upgrading my cam this fall. Currently running a 15 year old Straight Line Performance cam with adjustable rockers. What are the pro's and con's of a roller compared to a flat tappet beside the cost to go to Roller. Running a 68 440 .03 over with a Edelbrock Performer RPM intake with a 650 AVS-2, Pertronix 3 Flame thrower distributor coil and wires. 4 speed car

 

[BeepBeepRR]

Roller cam isn't supposed to wear out like old flat tappet cams. Tons of modern engines use Roller cams. LS engines, New HEMI engines. But then again you get failed valve trains on modern engines too. If you run high zinc oil old flat tappets should last a long time. Its a good question I would like to know the answer to as well. The cost is 3 times as much.

 

[1 Wild R/T]

The cost once you sort through all the extra changes is more than three times as much... New pushrods, new oil pump drive, new fuel pump pushrod, thrust bearing...

Figuring out if the lifters are gonna live or be one of the ones that fails at the roller.. Or is the oil pump drive gonna live or fail, same for the fuel pump pushrod...

There are plenty of advantages to rollers but don't kid yourself, there are plenty of failures waiting to bite you too....

 

[MoparMur]

I'm assuming you already knew the extra cost involved with a roller setup. There are many advantages to a roller cam and lifters. Among them: No question the cam can take more load with a roller lifter. As the roller cuts down the friction on the cam (hence less loading) the ramp profiles on the cam can be much steeper/quicker than a flat tappet lifter can accommodate. This allows for very modern profiles to be used, profiles that been developed in very recent years as cam technology has advanced. You already have adjustable rockers, so if they are in good condition that will save you some money. Valve springs are generally roller cam-specific, but on a 15 year old engine you'd be wise in changing them anyway. Yes you may need a few items to complement a roller cam, but if you are looking for a large power increase I'd do it. You don't mention what heads you are using, but if you are looking for substantially more power, a good bumpy roller with aluminum heads with a c/r around 10.5-11 to 1 will really make a difference. Of course a bigger carb and headers will be mandatory too. You don't mention a budget you want to stay within (maybe you don't care about the cost?), so I may be advising you with ideas that just aren't in your budget. Even changing nothing but the cam you have to a modern grind could gain you some power I'm sure. We all know that to get more horsepower it takes money, no way around it. How do I know? My son and I just finished his 440 adding Edelbrock E-Street heads and a Comp roller setup on his '70 440 motor. It had small chamber ported '67 440 heads on it before with a solid flat tappet Comp cam, and it ran high 11's. With this new setup he's not run it at a track yet, but the power increase by the seat-of-your-pants is noticeable. Cost? About $5500.00 CDN. with freshening up the bottom end as well. So it's all gonna depend on what you want and what you want to spend. Sorry to make this so long-winded, but the bottom line is, yes, a roller is a fine choice in my mind.

 

[66Satellite47]

All depends on what roller grind you pick. My Comp 720/276@.050 slowed the car down about 4 to 5 tenths. Comp reground it to 660 280 & got the car back to what the mushroom cam had been. Later a 690 284 Lunati made a little more power, .04 or.05 at most. The mushroom is still my favorite.
New parts are surely different.

BTW I run a flat tappet in my 512 motor.

 

[BSB67]

You did not specify if you currently have a SFT or a HFT, and if you are considering a solid or hydraulic roller.

And we need to know your goal. Depending on your goal, any one of the 4 cam styles could be right for you. If it is to just eliminate cam failure, only you can determine if that alone justifies the cost difference. As mentioned, depending on what you get and how you use it, rollers are not without their own risks.

If it is performance, you'll have a hard time realizing much performance gain going from a HFT to hydraulic roller. The hydraulic component of the lifter is the weak link, not the style of the lifter bottom.

The better you identify your goals for us, the better the responses you'll get.

 

[ACME A12]

Break-in on a roller is certainly a lot less stressful these days...jus' sayin'...
Having said that - I still went with a Bob K HFT in my A12 (most recent engine build) and had no issues.

 

[Challenger340]

Generally speaking
* the faster you can whack the Valve open... and faster you can close it again = more power.
Of special note:.... there are Hydraulic Roller profiles, Street Roller profiles and Race Roller profiles.... with each generally requiring more V/Spring Pressure than it's predecessor.

More V/Spring pressure ensuring things stay where they are apposed ta ? against the ever quicker profile ramp speeds of each.
and,
also meaning more wear on the relatively short BB Mopar Lifter Bores that were really never designed/envisioned for those loads..... let be after already 50 years service as some Blocks are quite worn.....
rendering many Hydraulic Roller retro-fits at times a moot point(unbeknownst to the owners)....
as much of the Oil Pressure leaks out around the HR Lifter in a short/worn BB Mopar Lifter Bore rather than maintaining pump up against the higher HR Lifter V/Spring loads.
Some HR's get installed and work FINE !....
just say'in... that in some applications successful HR operation in a BB Mopar can be at times dependent upon Lifter Bore "condition" (wear present at the bottom of the Bore next to the Oil Gallery)

Street Roller profiles.... "in my opinion only" are the best longer term option if LOTS of street miles are intended in the street environment. They still run higher V/Spring pressures(165-170# seat and 420#'ish rates).... albeit, the V/Springs do seem to survive better longer term..... and they can make very surprising power that we've seen on the Dyno, far above similar sized HR's in BB Mopars.

Race Roller profiles make the most power hands down.... they also require more V/Spring pressures starting around 220# seat loads and around 525# to 550# V/Spring rates.
In a street environment they can be problematic in that typically operator error ... or lack of operator continuity over time .... can allow V/Spring pressure to wane/drop over time in the street environment and then BAD things can happen ?
I mean the V/Spring going away on ANY Cam can cause problems.... just seems to be more prevalent occurrence of V/Spring pressures going away with Race Roller Profiles when used in the Street environment and owners/operators fail to maintain adequate continuity/maintenance with their V/Springs/pressures/Heating & Cooling of the V/Springs in operation.

 

[451Mopar]

I think the 650 cfm carb may be a restriction?
As mentioned, cam "profile" Flat Tappet or roller make a big difference.
You can get an aggressive Flat tappet cam that performs like a mild roller.

Going roller is expensive with the valve springs, roller tappets, cam, thrust button, and bronze gear oil pump drive needed for the swap.
The roller is nice if you plan to experiment with different cams because the tappets can be re-used on a different cam, and don't need to do cam break-ins
I did not know anyone was making mushroom tappets and cams, but it might be worth looking into.
As David Visard mentioned in one of his videos, a flat tappet cam can get the valve off the seat quickly, but is then slows down by the lobe to tappet angle.

 

[Houle #382]

The cost of the roller to me is just not worth it for a street car so I'm going to stick to a flat tappet

 

[69L48Z27]

What does everyone think of the flat tappet lifters with the EDM hole? Seems like it should be better?

 

[1 Wild R/T]

What does everyone think of the flat tappet lifters with the EDM hole? Seems like it should be better?

I'm using a set in my current build... Used a set of the hydraulic version on my last build... Extra oil at the point of contact can't hurt...

Hydraulic version is a little different, they can't edm through the face of the lifter or it would loose it's oil & rattle every time you start the engine... Instead they create a path on the outside of the lifter body from the oil groove down the the face...

Crower, cam saver lifters... https://www.summitracing.com/parts/...zERpxmhBhTKdfrugbSUu1kNlY4plVLTYaAgqhEALw_wcB

 

[beanhead]

What does everyone think of the flat tappet lifters with the EDM hole? Seems like it should be better?

That's what I've been using on the solids...I figure that little extra oil squirt between the lobe and lifter faces has to be a good thing.

 

[69L48Z27]

I'm using a set in my current build... Used a set of the hydraulic version on my last build... Extra oil at the point of contact can't hurt...

That's what I've been using on the solids...I figure that little extra oil squirt between the lobe and lifter faces has to be a good thing.

I’m building an engine right now and going to go with them, can’t image it could hurt but I never used them before. Thanks.

 

[rikkitik]

I went through the same thoughts/questions recently. I decided to go SFT w/edm. And I'm very pleased with the results.
If you look at the adv/.050/and .200 duration specs of a well designed. 904 lobe, they can fare pretty well against moderate solid rollers. SFT's can get off the base pretty quickly. I'm not particularly fond of hyd rollers.
Mine is a "mild" RV/tow cam by adv specs,
270int/274exh. But .050, 243/247, .200 162/164 @ .584int, .596exh (gross@1.6). I went with a 108lsa (I like a choppy idle).
Even with a basic tune (10.3comp, TF240's, haven't checked AFR's yet) it blows the tires off over 2500rpm in 1st & 2nd on a 95 degree day no less.
It's in a .030 440 6 pack Challenger.
I've run solids on the street for years, and with reasonable maintenance, have never had an issue. This is (for me) the first time with edm's.
There are advantages and disadvantages to each, but I'll take the simplicity, and reduced cost of SFT. I don't feel (imho) there's much performance loss, particularly on the street.
Just my $.02

 

[BSB67]

Mine is a "mild" RV/tow cam by adv specs,
270int/274exh. But .050, 243/247, .200 162/164 @ .584int, .596exh (gross@1.6). I went with a 108lsa (I like a choppy idle).

Funny. Those are about as aggressive of solid flat tappet lobe profiles as you can get.

 

[66Satellite47]

Ya, not sure what motorhome that cam is good for. Maybe set up for big wheelstands.

 

[rikkitik]

It's a good 'ol Brookshire (UDHarold). Asymmetrical lobes, and at .016/.016, a whole lot quieter than the POS 268 hydraulic I took out.
The UD is seriously torquey though. Pull away from a dead stop in 3rd, with just a slight slip of the clutch. I've only spun it to 6k, but a VERY linear pull, and wasn't nosing over.
In retrospect, I might have chosen to swap the int and exh lobes, or at least gone "square". But I'm happy with it.

 

[rikkitik]

Funny. Those are about as aggressive of solid flat tappet lobe profiles as you can get.

But that is also what I was alluding to. A well designed .904 SFT can move fairly quickly. While aggressive, the UD's/Bullet ramps don't appear as aggressive as Hughes/Howard's offerings, and (generally) don't require as much valve spring.

 

[33 IMP]

I have run solid rollers in both a small block and big block, but both were in primarily strip cars, so no extended idleing. Lack of oil splash at idle is rumored to cause roller failure.
For my 496/540 primarily street/some strip, I'm gonna run a lunati solid flat, with edm lifters. I cant see the need for a few extra horsepower at an extra $1500 (about 20hp roller compared to a sft, according to engine masters) in a primarily street car. Especially when you can make 600hp with a sft.