[Lifetime Goat]

Its that time again where I have the opportunity to change my current camshaft. Motor is a 1970 455 soon to be .60 over, #64 heads ported to flow 230cfm, RAIII exhaust manifolds and 800 cfm Qjet. Current cam is Ultradyne 231/239 with 1.5 rockers. Rear is 3.55.
I want to stay with flat tappet due to cost and see that there are a lot of new grinds out there in the last dozen years. Are there any choices that should be considered for this use that I should consider? I was thinking of going slightly milder than the current cam. Any thoughts would be appreciated.

[vertigto]

What are you wanting to accomplish and what don't you like about your current setup?

[Lifetime Goat]

I want to use on the street and be able to hit the pedal and feel the torque. My only objection with the current cam is the lateness that some of that power kicks in. I could certainly keep it but if there was a more tamed version with a lower rpm band that would also be fine. I have heard about Lunati Voodoo and Comp have some newer grinds and was looking for some input.

[Steve C.]

For clarification, can we presume the cam in use is the popular Ultradyne 288/296 hyd flat tappet ground with a 110 lobe separation ? If so then for a fair evaluation to other similar brand lobes note it's seat duration is rated at .0045" tappet lift.
As mentioned it is 231/239 at .050" tappet lift. The .200" duration is 143 and 151 degrees. Lobe lift is .3233" and .3383".


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[Bob Dillon]

Originally Posted by Lifetime Goat

I

" I could certainly keep it but if there was a more tamed version with a lower rpm band that would also be fine."


I think you've answered your own question there.

[Lifetime Goat]

Yes I think I found my answer already. I spoke to the good people at Bullet Cams and have a plan. Also read the MANY threads on this similar question, which I should have done first, so I think I have a plan. Thanks.

[Steve C.]

You can't have your cake and eat it !

Duration has a marked effect on a cam's power band and driveability. Higher durations increase the top-end at the expense of the low-end. Lowering the duration will do the opposite.

Some sources suggest that 0.050 duration is closely related to the rpm range where the engine makes its best power. But others will suggest there is more involved.
Also moving the lobe separation to something wider has been suggested it will broaden the power band.

Not a recommendation, but for conversation here.... consider on the intake side using the Comp Magnum High Lift lobe with 286 at .006, a similar 230 at .050, more .200" duration with 152 degrees and the additional lobe lift with 0.3770".
And custom ground with a wider 112 lobe separation.

And a BIG fwiw, Tim at Bullet Racing Cams is great to deal with!


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[scott70]

Same cam but with Rhoads lifters,,,been there done that. It makes a difference.

[TransAm 474]

A simple proven camshaft for combinations just like yours, is the Crower 60919 along with Rhodes lifters. Cliff and others have ran well into the 11's with that camshaft in combinations similar to yours. It should be plenty street friendly with your high compression(assuming you have flattops), and Rhodes lifters, and still be easily compatible with pump gas.

[Steve C.]

Consider the intake lobes on two cams, both with the 'same' 230 degrees duration at .050" lift, both ground with the same 112 lobe separation. Now consider the entire lift curve between the two....

cam 1
A whopping 304 degrees advertised duration tamed down with Rhodes lifters, 139 degrees duration at .200" lift and .470" valve lift.
And with a SYMMETRICAL profile 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.

cam 2
286 degrees advertised duration, 152 degrees duration at .200" lift and .565" valve lift.
This cam being ASYMMETRICAL with the 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.


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[Formulabruce]

This should get to what, 15, 20 pages?

[PontiacJim1959]

Originally Posted by Formulabruce

This should get to what, 15, 20 pages?

Possibly more as holiday season is just around the corner and many will be at home throughout these holidays. What better way to spend your time as a camshaft technician and intake/exhaust flow engineer with a minor in pressure waves resonance?

[Steve C.]

And don't forget area under the curve, always entertaining..........

https://www.speed-talk.com/forum/vie...12056&start=15



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[Tim Corcoran]

I am not sure what chamber size thee 64 heads have but do you know what your compression is? This will have a big impact on what cam to use as longer duration bleeds of dynamic compression and vice versa. Rather than changing cams you could put Rhoads if you don't mind a little ticking as has been already suggested as that will bring your power in much faster or install a 2500 stall torque converter. Either one of those options will make a big difference. What is your static compression ratio?

[i82much]

you could start by checking the cam timing, maybe it needs a new timing chain or to be advanced a bit.

[Steve C.]

My apology is in order here. In my post number 10 above the specifications for cam number two were for a hydraulic roller lobe, a obvious mismatch. That said a similar concept could be demonstrated using a hyd flat tappet lobe to compare with the first lobe. Just not as 'extreme' .


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[TransAm 474]

Originally Posted by Tim Corcoran

I am not sure what chamber size thee 64 heads have but do you know what your compression is? This will have a big impact on what cam to use as longer duration bleeds of dynamic compression and vice versa. Rather than changing cams you could put Rhoads if you don't mind a little ticking as has been already suggested as that will bring your power in much faster or install a 2500 stall torque converter. Either one of those options will make a big difference. What is your static compression ratio?

Those 64 heads advertise as 87cc chamber. My calculations say that it would have right at 10-1 compression, assuming the block hasn't been decked, heads not shaved, and using a .039 head gasket.

[ponyakr]

Originally Posted by scott70

Same cam but with Rhoads lifters,,,been there done that. It makes a difference.

This ^. But it seems that most nowadays hate the "tick".

This Howards has less adv duration & a 114° LSA. Should idle better & make more low end power. Rhoads would give it even more low end, below 3000 rpm.

https://www.summitracing.com/parts/h...w/make/pontiac

If you don't mind paying over $200, for a HFT cam, the Crower 60243 might be the next step below that Howards.

https://www.crower.com/camshafts/pon...m-284-hdp.html

Here's a couple of more, just under that.

https://www.summitracing.com/parts/c...IaAusEEALw_wcB

https://www.summitracing.com/parts/hrs-410141-12

Then of course Paul Carter has recommended a Voodoo cam for all sorts of Pontiac engines, including those with higher CR.

https://www.lunatipower.com/voodoo-h...8-268-276.html

if you really want a smooth idle & won't be going past 5000 rpm, then somewhere around 220° @ .050 might be plenty of cam.

https://www.lunatipower.com/street-m...8-276-286.html

It has been said that many cam companies will grind a cam with any LSA you want. Some say that a 112°-114° LSA will provide better street manners than one with a 110° or lower LSA. BUT, then SOME will argue that an LSA even lower than 110° is better. I'm done.

[Skip Fix]

Butler used to sell the UD 280/288 when he carried UD cams. A friend has it in a 72 455 HO and it does fine. I have the 296/304 in my 78 TA on a 112 LS. Bullet or Lunati have the UD lobes and can put them on any LS you want.

[Steve C.]

"Bullet or Lunati have the UD lobes and can put them on any LS you want."

Agree and good people to deal with, they have done my last three cams with Ultradyne lobes. Apparently the OP is in contact with Bullet Racing Cams and they have a plan.



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