Yeah, there was a discussion about those not too far back, I think it was the SB Forum....or Racer Forum..there's a member that is searching for a tappet(or more) as well.
Never had My hands on one tho'.
Hughes cam?
- Thread starter glockr
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Never had My hands on one tho'.
"Huge gains" I think we're losing track this is a slant 6 we're talkin about. IMO, unless you're racing for money or points, it's splittin hairs what lobe you go with. All things equal, how much do you think a .903 specific lobe will net?
As far as Hughes goes I've been down there a few times some years ago, I'm about 100 miles away from them.
Even though at the time I was working on a 318 magnum, rather than a/6, they really didn't seem all that interested in what I had going.so I didn't spend much with them, as a result.
Even though at the time I was working on a 318 magnum, rather than a/6, they really didn't seem all that interested in what I had going.so I didn't spend much with them, as a result.
Rat Bastid
Dunamis Metron
It’s not just about peak horsepower (it just KILLS me to say that) but it’s about power under the curve, manners, driveability, idle quality…things like that that don’t show up on a dyno.
My math above comes right off the Howard’s lobe list.
Both lobes are the exact same at .050 but the .904 lobe has less seat to seat timing (better idle and more idle vacuum) and by .200 lift the .904 lobe has far more area under the curve.
When you are laying out an engine build the .904 lobe allows you to do more without sacrificing the above mentioned things.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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If you plot lift against crank position/time, you will find the every cam spends waaaay more time below 50% lift than above it. So anything you can do to increase air-flow at low lifts, nets big dividends.
Therefore, your first line of attack is a fast-opening lobe. Which provides other benefits which @Rat Bastid points out. Running a cam that is one or more sizes bigger, with the same .006 advertized is a very big deal.
The bigger cam will provide more scavenging and the additional overlap will help get the intake charge moving, which, as you know with slantys, the carb can be a really long way upstream.
Yet, the smaller advertized specs, will idle at a higher vacuum, making drive-ability more fun.
I have recently been watching some videos put out by David Vizard, with Unity Motorsports; good stuff. One of the things that he is pretty gung-ho about is his LSA formula. He is adamant that the best LSA for any engine will be spit out by his formula.
It goes like this:
128 less (cubic inches per one cylinder/intake valve diameter x .91) = LSA
For my 2.02 valved 367, this works out to an Lsa of 107.33.
Well that's pretty darn close to the 292/292/108 I once ran, which was gangbusters.
For the slanty with 1.62 valves, this comes to 106.94.
How about you try it, lol, and give us a report.........
Therefore, your first line of attack is a fast-opening lobe. Which provides other benefits which @Rat Bastid points out. Running a cam that is one or more sizes bigger, with the same .006 advertized is a very big deal.
The bigger cam will provide more scavenging and the additional overlap will help get the intake charge moving, which, as you know with slantys, the carb can be a really long way upstream.
Yet, the smaller advertized specs, will idle at a higher vacuum, making drive-ability more fun.
I have recently been watching some videos put out by David Vizard, with Unity Motorsports; good stuff. One of the things that he is pretty gung-ho about is his LSA formula. He is adamant that the best LSA for any engine will be spit out by his formula.
It goes like this:
128 less (cubic inches per one cylinder/intake valve diameter x .91) = LSA
For my 2.02 valved 367, this works out to an Lsa of 107.33.
Well that's pretty darn close to the 292/292/108 I once ran, which was gangbusters.
For the slanty with 1.62 valves, this comes to 106.94.
How about you try it, lol, and give us a report.........
A 225 worked out to ~102.5° LSA when I did that for stock valves couple years ago,
Exactly, the same as a better flowing, more efficient head allows for less cam for the same output..better torque curve.
It's important to point out not all "Mopar" lobes are the same, that's all. Some are no better than an excellent aggressive .842" design, and the most aggressive are going to require more than a standard valvetrain can handle by a mile, goals, expectations, budgets....
I understand that. It's an advantage all the way around, there's no argument. But.....how many guys run and run FAST at the track and on the street with a Ford or Chevy lobe? A LOT. Yes. I know. They could be faster. But then, so could everyone.
If You go from a run of the mill Magnum lobe to a fairly aggressive Mopar lobe, it could be worth 15-25hp on a 225 easy. But with the long pushrods, and requisite spring loads, stock components are out. Better pushrods are always a good idea on tall-deck Slantys anyways, but may not be in the original budget plan. Springs should always be so, it's a matter of degree & related cost, but expected. I'll try to link My post in Steve's spring shimming thread, about My project.
Post in thread '340 xhead spring shimming, height and pocket question(s)' 340 xhead spring shimming, height and pocket question(s)
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Besides shooting for 9.5:1, I recommend the larger valves, the 225 is grossly under-valved. If the head recon is going to require new ones anyway, that's an automatic decision, that simple.
Even though the Intake-biased dual-pattern cams haven't proven out to "help", they won't hurt, that bumpstick should work fine. I also highly suggest stronger 3/8" pushrods, if they'll make it in the budget, get them.
my68barracuda
Well-Known Member
I called Oregon Cam Grinding today
and spoke with Ken. He confirmed that the Oregon catalog does include some .904 lifter diameter specific lobe, but to get one you must be specific and request a Mopar .904 diameter compatible grind.
The Oregon catalogue does not break out the Mopar profiles separately, so if you want an aggressive and fast opening cam profile you have directly request that and then be patient as the Oregon rep pages through their catalogue.
and spoke with Ken. He confirmed that the Oregon catalog does include some .904 lifter diameter specific lobe, but to get one you must be specific and request a Mopar .904 diameter compatible grind.
The Oregon catalogue does not break out the Mopar profiles separately, so if you want an aggressive and fast opening cam profile you have directly request that and then be patient as the Oregon rep pages through their catalogue.
My wife has me busy with honey do's today, I'll give them a call tomorrow.
And as Rusty started to say above, it depends on what YOU want out of YOUR engine, as to whether that advantage would even come into play. A daily driver, a mpg champ, a truck, (that's used at one at least) probably won't get into high enough RPMs for such an aggressive cam to the point where you'd see the difference in a "regular" cam design, or one where the lobes are ground to work better with a bigger lifter.
But then again the setup is probably pretty identical, as far as doing the actual cam grinding operation, and the time spent doing the grind, probably is pretty close to the same as " most of" the work they would do, so I can't see getting what you would want out if them, being any more cost than their"regular" work .
Maybe you might see an advantage on another sense, as being that they probably don't get asked for such a profile very often, meaning that if it calls for any different tooling than the normal stuff, could it be that such a cam could be kept on tighter tolerance because of being cut with tooling used less often and therefore less "worn out"?
But then again the setup is probably pretty identical, as far as doing the actual cam grinding operation, and the time spent doing the grind, probably is pretty close to the same as " most of" the work they would do, so I can't see getting what you would want out if them, being any more cost than their"regular" work .
Maybe you might see an advantage on another sense, as being that they probably don't get asked for such a profile very often, meaning that if it calls for any different tooling than the normal stuff, could it be that such a cam could be kept on tighter tolerance because of being cut with tooling used less often and therefore less "worn out"?
I'm sure you're right in the ballpark. There's no question about it. But where "I" am with what "I" am doing I actually WANT a slower, lazier lobe. I want dead nuts reliability and no parts breakage due to stress caused by aggressive lobes. What I have now is a PERFECT example of that. I can drive this car every single day and not have to worry about anything being too aggressive causing stresses that might break things. I'll take a 15-25HP cut any day for that. Now, were I building something to blast down Reynolds Drag Strip, then things would be different.
That's how I understood him to say it as well....but he was having a bad talking day and as always, I was having a bad listening day. LOL As I said above though, with what I am doing, a lazier lobe is just fine with me.
my68barracuda
Well-Known Member
I bet that the cam lobe profile machining done today is via a CNC process. The lobe masters would not be physical parts. They exist as math data.
my68barracuda
Well-Known Member
The cutters and tooling would likely be common and used on all cams. It’s the program (math data) that moves the cutters to a specific tool path that is job dependent.
If the 225 is grossly under-valved as claimed in post #35, then a 102-ish LSA as mentioned previously is a good idea. Use duration to control power range, idle quality.
If you think 102 is tight, Jon Kaase, multiple EMC winner, used a 98 LSA cam with 92 ICL to win the contest with a 400 Ford engine that made 660 hp with a broad tq curve & a cam that was not that huge in duration.
If you think 102 is tight, Jon Kaase, multiple EMC winner, used a 98 LSA cam with 92 ICL to win the contest with a 400 Ford engine that made 660 hp with a broad tq curve & a cam that was not that huge in duration.
The Cleveland family can be impressive if built right.
I think the post you're referring to said 102 ICL (intake center line). ICL is different than LSA (lobe separation angle) I think. I agree with your premise (tighter LSA is better for under-valved engines), but is there a company that would even grind a /6 cam on a 102 LSA (and be able to get it to me by end of May)? Not sure if a regrind can take a 108 LSA all the way down to 102 - that's a pretty big change.
Rat Bastid
Dunamis Metron
No, Bewy has it right. He’s talking about LSA not ICL. He knows the difference.
The biggest thing about getting a 102 LSA or the tighter ones like Bewy mentioned above is getting cores that will take an LSA that tight.
Cam cores are cast with the lobes roughly in place. And you can’t go very far one way or the other once the core is made.
There is more than one reason why the de facto LSA is 110. And that’s most economic.
A slant 6 core MIGHT can get down that tight, but it'd look like a cheater cam with the base circle on par with the cam core. The way to do it would be to just have a new core made.
In post #31 I was pointing out to AJ the LSA I got using DV's "128" rule formula, NOT the ICL, & it's pretty much right on. The "6681" Purple Shaft I have is 276°/276° .490"/.490" with a 104 LSA & I installed it on a 101° ICL.
You're simply introducing the possibilty of worn machinery & tooling, or operator errors, that isn't the same as the old physical master duplication errors. A program will duplicate(if correct) the lobe perfectly every single time, given top maintainance & operation/practices.
Like the difference between tracing an image with a pantograph over & over, vs running copies with the jet printer, sort-of, lol!
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