[Steve C.]

ta man's post can relate to the subject of cam intensity here:

http://www.4secondsflat.com/Cam_Design.html

Also related take note of what Harold Brookshire points out in his post number 6 here:

https://www.chevelles.com/forums/13-...y-formula.html


Also noted in this thread and important to keep in mind is the seat to seat or advertised specs can vary with different cam companies, already mentioned is .004" and .006".
Then there is the ramp design as described here from Lunati and touched upon by Harold above....

SYMMETRICAL: is a term that refers to the "profiles" of the opening and closing ramps of a camshaft lobe. All "early technology" camshafts were ground on a symmetrical design, meaning both sides are exactly the same. That is to say the profile of the closing ramp is a "mirror image" of the opening ramp

ASYMMETRICAL: refers to a camshaft lobe profile where the opening and closing ramps are not exactly the same. The reason some camshafts are this way is to try to achieve an opening ramp profile that has a high velocity and a closing ramp profile that has a slower velocity. In this way the valve can be set down more "gently" than the rate at which it was first opened.

And important is to evaluate the duration at 0.200" tappet lift. That can open up a bucket of worms....

http://460ford.catsboard.com/t25901-...ation-200-lift

I know Lee Atkinson who posts here and designs cams often compares the difference between the seat duration and the .200" duration.


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[slowbird]

Originally Posted by MartyVi

Want to know what is the experienced users tried for roller cam profiles and recommendation.
My current build is
455+.030
4.25 stroke Eagle kit with Mahle pistons and H beams
Edelbrock 87cc heads
About 10:0-1 CR
Street use and highway driver. Has 3:08 now with automatic trans.
Looking to put a roller cam. Who’s brand of cam ramp specs ?
Aside from which rollers to use as we have been reading much on that.
Lunati Howard’s Comp Bullet etc
Please tell me your experience.
Thanks

Contact Paul K and get a cam from him. He knows what he's doing and you can't beat his prices.

[MartyVi]

All good info.
I read and re-read David Vizard theory on camshaft selection. Good stuff to ponder. Wanted to test the waters here because you guys live in the real world. Theory doesn’t always translate into a street engine and chasing 8 hp isn’t that big a deal for me when one is at around 500 hp level. I do understand everything written here so don’t feel like you wasted any time here. I appreciate. And honestly with this virus I have more time on my hands to give myself a bigger headache. Lol

[Jay S]

There are differences between the big intake tracks like what you would see on a BBC or a Ram air V and a typical Pontiac head. The engine with big cross sectional ports like less seat timing and to keep velocity’s higher, usually use a little narrower LSA too. An E head Pontiac has a pretty small cross section on the intake to some other heads. Personally I don’t think Vizards BBC cam theory and Pontiac engine theory play all that well together.

The other guys mentioned the .2 specs and lift’s effect on the engine. If the engine has enough head flow and velocity the bigger .2 specs with the same seat and .050 timings can actually make the engine more docile. Extra lift can drop the power peak rpm and raise the average power some from filling the cylinders more. When you add good head flow to these bigger cams most people would be amazed how they do on the street. Doesn’t really sound like there are reasons to push the limits to much for your planned combo.

[MartyVi]

Originally Posted by Jay S

There are differences between the big intake tracks like what you would see on a BBC or a Ram air V and a typical Pontiac head. The engine with big cross sectional ports like less seat timing and to keep velocity’s higher, usually use a little narrower LSA too. An E head Pontiac has a pretty small cross section on the intake to some other heads. Personally I don’t think Vizards BBC cam theory and Pontiac engine theory play all that well together.

The other guys mentioned the .2 specs and lift’s effect on the engine. If the engine has enough head flow and velocity the bigger .2 specs with the same seat and .050 timings can actually make the engine more docile. Extra lift can drop the power peak rpm and raise the average power some from filling the cylinders more. When you add good head flow to these bigger cams most people would be amazed how they do on the street. Doesn’t really sound like there are reasons to push the limits to much for your planned combo.

And that’s why I’m here.

[pastry_chef]

Originally Posted by Jay S

Vizards BBC cam theory

I have confidence his theories and target math will work for most any platform.
With his Torque Master program comparing to "Pontiac" norms it is obvious most street Pontiac's are low on induction flow and valve lift for target displacement and RPM.
It would be cool if one day TM can be used for valve timing for a Pontiac V8, the program has platform specific calibration.

http://speed-talk.com/forum/viewtopic.php?f=1&t=46038

On page 4 an LSA comment from Len Caverly, a Pontiac builder with his own dyno and has competed in Engine Masters.

"I do Pontiacs and yes a 108 cam will out perform a 110 or 112 cam every time on a typical 455 street build. It may not idle better but will certainly perform better!!!! And if I am serious about a street strip build it will be tighter than that.
Len C"

Pontiac Dude (Ken Keefer) and Paul K here have also tested LSA back-to-back on Pontiac's, their testing agree with Len.

95% of those reading this here (street forum) would be thrilled with 11 something performance. For this a car that weighs 3700 ish pounds running a decent 455 engine, LSA does not "need" to be optimal. Hell, run 116 if you want.

[Steve C.]

Vizard is a big proponent of valve lift and points out a typical 2-valve ported cylinder head responds to valve lift without a sacrifice of idle and low speed qualities. So is Tilden Technologies:

"Once the four timing parameters are established, the cam should be designed for maximum lift."


https://www.tildentechnologies.com/C...rformance.html


Bottom line, the engine wants all the lift it can and thrives on it so run as much as mechanically achievable or unless prohibitive because of cost limitations. That said, this from Lee Atkinson in a related post from another Pontiac website.
And note his comments related to valve lift and note his use of custom cams rather that a shelf cam with a ginchy name....

Topic: What are the defining factors to choosing the right cam?

* Flow characteristics of the heads, to determine lift - It is silly to use a .450" lift on heads that flow well past .600". It is also silly, IMHO, to use high lift cams with heads (such as stock D-ports) that gain virtually no flow past .400" lift.

* Performance goals of the owner - what RPM range do you need most power? People often chase some arbitrary "horsepower" number, and end up sacrificing a lot of lower RPM torque in order to gain a little of upper RPM HP.

To me, the camshaft is the conductor of the performance. It should be selected LAST, and be designed to make the other parts work in harmony. There is no Magic-Cam that works best for everything. I've had about 100 cams custom ground over the last few years, and have only used a duplicate of a previous grind maybe 3 or 4 times.

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[Steve C.]

"Doesn’t really sound like there are reasons to push the limits to much for your planned combo."

Agree, and for the most part much of this information from me is conversation around the coffee table.

And pastry_chef's comment regarding using the wide lobe separation... if he does he can avoid stinky hair


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[slowbird]

Originally Posted by pastry_chef

I have confidence his theories and target math will work for most any platform.
With his Torque Master program comparing to "Pontiac" norms it is obvious most street Pontiac's are low on induction flow and valve lift for target displacement and RPM.
It would be cool if one day TM can be used for valve timing for a Pontiac V8, the program has platform specific calibration.

http://speed-talk.com/forum/viewtopic.php?f=1&t=46038

On page 4 an LSA comment from Len Caverly, a Pontiac builder with his own dyno and has competed in Engine Masters.


Pontiac Dude (Ken Keefer) and Paul K here have also tested LSA back-to-back on Pontiac's, their testing agree with Len.

95% of those reading this here (street forum) would be thrilled with 11 something performance. For this a car that weighs 3700 ish pounds running a decent 455 engine, LSA does not "need" to be optimal. Hell, run 116 if you want.

If you tighten up the ls you better increase duration, in my opinion

[MartyVi]

Originally Posted by Steve C.

"Doesn’t really sound like there are reasons to push the limits to much for your planned combo."

Agree, and for the most part much of this information from me is conversation around the coffee table.

And pastry_chef's comment regarding using the wide lobe separation... if he does he can avoid stinky hair


.

Yes for my purposes I agree on the wider LSA. Don’t want stinky hair either.
But one thing that I got from Vizard was that tighter lobes gave you more overlap and that allowed more fuel into the cylinder starting at very low lift and up. Scavenging.

[MartyVi]

Originally Posted by Steve C.

"Doesn’t really sound like there are reasons to push the limits to much for your planned combo."

Agree, and for the most part much of this information from me is conversation around the coffee table.

And pastry_chef's comment regarding using the wide lobe separation... if he does he can avoid stinky hair


.

Right. This has been hashed a million times but coffee banter is still enjoyable depending on who’s talking. I look forward to our conversations here.

[Steve C.]

“Lobe separation angles,” he continues, “are influenced by the camshaft grind. If a street car has smaller lift and duration numbers, they might run 112 or 114. Widening their separation angle helps increase upper rpm power output. Alternatively, if you are running a bigger camshaft to gain maximum top-end power, cam makers often suggest reducing the lobe separation angle to recover power lost in the lower rev range.”

https://www.enginelabs.com/engine-te...-relationship/

Offered for general interest only, some might suggest what you read on the internet regarding lobe separation does not apply to a Pontiac ! I've run a few combinations with a 108-110 lobe separation... never a complaint from the wife


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[pastry_chef]

Originally Posted by slowbird

If you tighten up the ls you better increase duration, in my opinion

Agree, also put emphasis on valve events. IO, IC, EO, EC.

Overlap is extremely important.
It is controlled by the Intake opening and exhaust closing and is not directly
related to LSA, or the difference in duration between the intake and exhaust.

After I calculate the Intake opening and closing points, I calculate the exhaust
closing point based on desired overlap, then the exhaust opening point.
If the exhaust duration ends up being 12 degrees longer then the Intake, or 12
degrees shorter, it's irrelevant.
Mike Jones
Jones Cam Designs

Page 6 - Speed Talk http://www.speed-talk.com/forum/view...29382&start=75

I look at "overlap" as a funtion of the exhaust. To get the desired overlap area, I keep the Intake opening the same, and change the exhaust closing and lift.

For anyone who doesn't know Mike Jones, I'd say one of the top five cam men in the world now. His cams won 3 Daytona 500's over a 10 year period. A "thinker" as Smokey said may want to read his words,.

[pastry_chef]

Originally Posted by Steve C.

I've run a few combinations with a 108-110 lobe separation... never a complaint from the wife

I didn't think so.

[76TA462]

I'm using a similar combination to start of string. But with 10.4:1 using Dave's KRE 85cc heads although with a 140 seat. Also using Dave's Old Faithful. My car is used as a streetable performer and I am very happy with the combination. Used a custom Bullet previous and although fun, the Old Faithful simply pulls better across the rpm range. Using a 10" Jim Hand Special behind a tired TH 400, for now :>).

[pastry_chef]

Originally Posted by 76TA462

custom Bullet

Do you have the Bullet cam card?

[76TA462]

Sure do. Ground in 2010. 4/7 swap. Dur at .05 is 224 226. Gross lift .551 and .555. Dur at .006 is 284 277. Separation 112 for degreeing to 109. Grind No. PO 284/277-12HR. Part No. 507000. Designed by a member of this forum, but at the "other one" at the time. The cam was meant for crazy fun and low-end torque. Might have lost some higher rpm HP but gained below 4500. Used with Performer intake. Since then I swapped over to the RPM intake and other changes, which is why I changed to the Old Faithful. I don't have dyno numbers.

[pastry_chef]

Originally Posted by 76TA462

Grind No. PO 284/277-12HR.

144 @ .200 wasn't going to compete against the 160 @ .200 of the OF.

Intake
HR284/367 284 224 144 .3670 .000 CRA

Exhaust
HR277/370 277 226 151 .3700 .000 CTA

[76TA462]

That's for sure, and seat of the pants agrees too. But, my goals (and other parts) were very different at the time and the Bullet was a hoot. And a lesson to me that "small" grinds can be awesome if designed accordingly.

[Steve C.]

Follows right along with Cliff Ruggles general adage of not running under 230 degrees intake duration in a 455 based combo.


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