Single vs dual pattern cam ....

[mala]

……and you must have also missed the memo on the best lsa.

If I remember correct it is common on BIG engines had wide LSA (116-118) to soften the hit when you nail it at starting line...... Especially when you have small tires car.
But I am far from a engine builder or cam expert, but I guess there is a wide range of LSA because you can build an engine many ways and have different purpose.

 

[rikkitik]

The poor guys at TrickFlow musta' figured they missed on the exhaust port.......their own cam is a split pattern "crutch".......
Though you're only looking for 500rpm or so, 512 cu in, TF240's, and 1 7/8" primaries are going to conspire to fight you a bit.
(edit for clarity)
Not at all meaning the TrickFlow 240's aren't great heads, I'm running a set myself. Only meant to say that they tend to "peak" around 5800-5900 on 512's, 54-5600 on 540's.
The 1 7/8" primaries are kind of at a "break-over" point on 440's. At about 600hp/6000rpm, it's time to consider stepping up in tube size. 1 7/8" will do it, but 2" seems to free up some top end. So, on a 512, I would be thinking they're a bit undersized.......Maybe give a call to ARH, or TTI to check it out.
As to my opinion, take it fwiw, "just an internet opinion."

 

[dvw]

The more duration you run the wider the LCA to maintain a given amount of overlap. Add 30 degrees on the intake and exhaust durations with the same LCA. Think about what that does to overlap.
Doug

 

[68 HEMI GTS]

I looking for a new SFT cam for my street car. Found two camshaft that caught my attention.

dodge
dodge

They look pretty similar but they are single and dual pattern, is here anyone ho can explain the character of the two cam profils? And is there one of them that is more street friendly / easy on valvtrane?

Most camshaft today is dual pattern but is that the hot ticket in every engine? I have a single pattern SFT today and it work perfekt..... but I have not tried a duel pattern maybe a better choice?


Engine is:
512 cu
Tf 240 oftb
10:3 comp
Single intake
Headers 1 7/8 x3
Full 3" exhaust
4.10 with 28" tires
Flash stall 4200

Weight is 3860

Thanks!

Very similar to the combo in my roadrunner. I’m just a bit heavier at 4000# (with me in it). PRH had comp grind a cam for my combo. Excellent running SFT. It’s a dual pattern. Honestly when I wear it out I may re-order this cam, it’s gonna be damn hard to beat. I use 1.6 rockers on it.

 

[mala]

The spec on that cam should be a good match I believe. I have 1.6 rockers to, .624 lift is little more that I have now. Is it easy on the valvetrane?
What lifter do you run? EDM?

 

[68 HEMI GTS]

The spec on that cam should be a good match I believe. I have 1.6 rockers to, .624 lift is little more that I have now. Is it easy on the valvetrane?
What lifter do you run? EDM?

Yes easy on the valvetrain. Don’t think I’ve had to adjust any valves in 2+ years. And it gets driven a lot and hard. I have Howard’s EDM’s on it. Dwayne used Ford lobes so it’s not as hard on the cam lobes for street use. We chose a little better durability vs max ramps.

383 man runs the same lobe family on his cam in his 493 as well. His would be “up a size” at 264/270. Probably a good choice as well.

 

[mala]

I like a what you say about ramps, that is exactly what I looking for. I usually go over my valves once a year, but that is often unnecessarily.
Was the nitrided a good choice? I have read different opinions about nitrided.

 

[68 HEMI GTS]

I like a what you say about ramps, that is exactly what I looking for. I usually go over my valves once a year, but that is often unnecessarily.
Was the nitrided a good choice? I have read different opinions about nitrided.

It was worth it to me, I’d do it again. I don’t have a whole lot of faith in more radical flat tappets so I prefer extra insurance.

 

[Budnicks]

I'd highly suggest going to MotorTrend & Engine master show
Youtube or where ever you can watch it

season 5 episode 65
(something like) Engine Personality, camshaft LSA Explained
IIRC it was tested on an RB combo, (440?) with a Tunnel ram (Maybe ?)

&

season 6 episode 101
(something like) split duration/lift cams tested
albeit IIRC the tests are done on a SBC, still the same deal

2 good episodes, pretty damn well explained too
results prove it

------------------------------------------------------------------------------------

IMO for any engine running wide open throttle (WOT)
loose 7"-10" converter, or even a clutch, with slicks/Drag Radials & steep gears
like any drag car IS/should be

I'd go with spit duration/lifts & usually more lift/duration on the exhaust
even with heavily professionally ported heads,
or 1:6 &/or 1:7 rockers, big exhaust/big tube headers
multiple; 2x4bbl tunnel, split dominators (8bbl/4x2bbls)
or cross-ram, factory or STR style 6bbl
or big single carb/dominator, multiple different styles of induction & exhaust
& especially EFI
all of my full roller motors or any real true full race cams/for racecars,
all were/are split duration, period
the other stuff is ancient/old technology, especially today
it doesn't hurt you on the street either

almost always used with a tapered 2 or 4 port (or multiples)
or a phenolic (especially on a street/strip car, even a 6bbl)
carb/s or TB spacer too

Win Win

your results may/will vary, probably only slightly
that's my recommendation

good luck & have fun