Solid Flat Tappet VS Solid Roller

If I change over to solid FT from a solid roller.. how
much difference do I need to add to the FT to equal
the roller..I'm gong to a bit smaller cam then what the
roller is.. the roller is a 105lsa installed at 105..
260/270with .640/.640 with 1.5 rockers.. this is in a 416
so IF I change over to a FT how much more do I need to
go to come close to the roller... one thing that will
change is the LSA..I'm going to a 110lsa for the injection
so any help is welcomed.... I know the ramp rate will be
slower but if I go larger would it help..I would like stay
at about 260-265 duration and about .600-.630 lift
thanks guys

Look at the lobes for Ø.904 tappets offered by Bullet/Ultradyne, they have pretty fast ramps and depending on how aggressive your current roller is, the flat tappet could even ramp faster

It seems that you're asking how many apples does it take to equal an orange. Obviously, the difference in two similar spec. cams, FT vs. Roller, will be the lift area under the curve. I don't think there's going to be any mathematical equation that can give the answer to your question, since each cam profile would offer its own variable. It would seem that a FT cam with substantially more lift at the same .050 duration would require faster ramp-rates, and thus may mimic the valve action of a roller, without changing the running characteristics too much, being of the same breathing duration. But by the nature of the pieces themselves, the flat tappet will never be able to approach the ramp-rate of the roller. I'm sure I'm not describing anything you don't already understand though, Mike.

I'd call a reputable cam company and ask to have a conversation with one of their technical experts (not a customer service phone jockey), and see what they have to say.

the more "flat tappet cam" you add the greater the parasitic load to drive the valve train. what's less friction; a skid or a wheel?

some years back i put together a solid roller bracket engine with 750lbs open spring pressure. at about the same time i put together a mild hydraulic flat tappet engine with less than 300lbs open spring pressure. the break over torque for both engines completely assembled was the same 75lbsft. what i'm getting at is adding more lobe and spring on a flat tappet may never equal a "wheel".

I know they will never be equal.. but just something
close... if I add a bit more lift and a bit more duration
will get get close(to what I am running now)...I can go with a
FT at a much cheaper price than a roller.. if I could get the
roller cut to a 110LSA I would just do that..but from what I know
that isnt gonna happen

I don't think you'll be able to get the same lift unless you go with a 1.60 rocker arm.

Comp MM lobes are 263/.606 or 267/.617 or 271/.627 so lift isn't what you're looking for.

My crane roller is 112 lsa, I a running a small cam at .620 lift and 248@.050, if you do it, have a custom ground 3/7-4/2 swap so idle improves and it will help on the FI parameters. Tim

I just ordered up a solid flat tapper...from Clay Smith
and all the parts to go with it..cam is 110 lsa,I will
have to change to my 1.6 intake rockers...no big deal,
springs for it with keepers and locks and AMC solid lifters
for push rod oiling... should be right inline if not a touch
more power due to the 1.6 rockers... George(the owner) is pretty
damn sharp when it comes to that stuff.... I was surprised how
quick they can get things out the door... this is a custom grind

Correct Andy.. due to the 904 lifter..but yes I have
to change over to 1.6 intakes... this gives me a .626
intake if I wrote it down right.... I tried 4 other
cam companies with no response...getting pretty fed
up with these companies

George at Clay Smith is sharp.... Been around longer than most "experts" have been alive.

Give Mike a call at jonescams.com.... He's usually up for a challenge.

Wouldn't it have been cheaper to just buy a new roller cam made the way you want it than to buy a ft cam and all those parts?

I already ordered from George...I'm sure I'll be happy

Well I was gonna say just have a wider lsa roller ground and have your cake and eat it too.

I wasnt happy with a few things.. cant grind in the
110lsa I wanted plus I wasnt happy with the EDM hole
in the rollers.. way to big.... and the cost for the
cam was $40 more for a new one over a regrind

Opinions probably vary but when you look at the very peak lift on a flat tappet, there is no truly effective "dwell" for the peak lift flow, other than you need it for the valve to change direction. but with a solid roller at say .650 lift, the "squarer" roller lobe sort of "parks" the valve (i.e., very little change in net lift...of course it IS changing, just not very much from one degree to the next) where a FT has to take the valve up and over to come back down.

Let's leave Lash setiings/valve mass and specific "opening/closing rates' out of the comparison for now.....So if you compare the head flow of a .650 roller to that of a higher lift say .700 or .720" lift (same running duration) FT you could say that you MAY have similar duration at .650 lift for both cams and MAYBE that little extra "up and over" between .650 and .720 can yield as much or MORE flow (depending on the head) as the roller "parking" the lobe at or near 650 for the (near) equivalent degrees of duration. But if that was the case, you could ramp up the Roller to .720 and so it becomes a matter of where you wish to draw the line.

Advantages of a solid FT, lower cost, weight and less to break/go wrong. Disadvantages would be friction/wear (especially with todays low zinc oils) and the obvious limitations of the flat tappet lifter base diameter...you roughly have 1/2" of the diameter of the lifter to open the valve and the other 1/2 to seat it, even with asymmetrical ramps you have more physical constraints. Whoever came up with the mushroom lifter was obviously trying to address that acceleration (rate of lift) rate.

It's hard to get true "apples to apples" but if you compare what you can get your head around, it's somewhat doable.

If I dont like this FT cam I'll go back to a roller but with
a wider LSA.. this one has a ton of lope to it.. if not heavy
on the brakes it each time it lopes it jumps forward some..
this cam runs real strong but the 105 lsa and the injection
dont like each other too well... yeah I can lower the fuel
map at idle.... if I dont like the FT cam I'll have a 110 lsa
roller made up... but also I'm not trilled with the EDM hole
in the bottom of the lifters.. it dumps way more oil than I
like.... glad you made comment of the zink.. forgot all about
adding that since I havent run a FT in more than 25 years..
and yes I know about the break in and the springs... whats the
strongest spring pressure you have ever run on a FT.. I was told
by the cam company that 140-145... I was thinking up to 150 but I
will try 145 first

I have 155 seat on my small solid ft, but i also have trend tool steel edm lifters.

I'm gonna run AMC lifters on this... I have to oil via
the PRs

253/255 solid FT w/standard lifters-no EDM hole.
170/350 pressure,ran the same springs w/cam 8 degrees
smaller with success.
Mike

This one would've worked too.

http://www.hughesengines.com/Index/produ...mp;partid=30272

George is a good guy. I always forget to mention Clay Smith when talking about cam companies that aren't comp.

His stuff should work good for you.

mine also has PR oiling.

I do like that cam...its a bit large for what I wanted but
I'm sure they make some smaller... I might look at some of
their others..and set the this one on the shelf..in the end
it could be cheaper

I bought a custom version of that cam also... I'll
put the Clay Smith in my back up engine or leave it
as a roller.. depends what heads I have on it.. the
one in the Rampage will take a couple of weeks to get
here but thats the one going in the 416... I can leave
the 1.5 rockers on it and put the W-5s on the 416... had it
ground on a 110 lsa.... plus I bought their light weight lifters...
so I have enough cams to last me for a while.. both rollers
and solid FT ones... damn these solid FT cams are CHEAP
compared to rollers