[Donovan]

Sounds great! Any porting to go along on the heads? What was your chamber size on those #17s?
I did a set of #17 heads and mine were mid 80s CC chamber, but responded well to porting even with stock valves. I'd do the 2.02 or 2.05 valves like you if I did it again.

Originally Posted by Rar_421

I have a 350 at the machine shop now,going .030 over,eagle rods and getting balanced,number 17 heads and going with the sbc 2.02 intake valve and having a warpath classic muscle car cam ..445/ 468,likely the white box 214/224-2801 cam, hopefully i can report back and let you know how it performs in a month or two

[Tim Corcoran]

Based on the simulations that Stan provided the Voodoo 703 outperforms all other cams discussed.

[Cliff R]

Maybe on paper, but realize that dyno simulations do NOT tell us how well a cam will work once placed in service. Idle quality, vacuum production, throttle response, power right off idle, and good power and efficiency in the "normal" driving range is NOT well reflected by peak and average power numbers.

From what I've learned from actually doing this coming up on 50 years now is that compression is your friend with these things. Higher compression makes MORE power (torque) at every RPM, all else being equal, and it allows for larger cams with more seat timing and offsets losses in dynamic compression from going tighter with the LSA as well.

I've never built a Pontiac 350, but if I did the FIRST thing I would do was to obtain a late 60's set of small valve small chamber heads (grocery getter variety) like 1969 #46 castings. I'd do some good valve and seat work, better springs, screw in studs and mill them so my "little" 350 engine was closer to 10 to 1 compression than 7.5.

At that point I'd cam it similar to what I do with my 350 SBC builds (the exact specs depending on application/use of the vehicle). Then I'd enjoy closer to 1hp/CID or even a bit more, with good idle quality and street manners vs trying to defy the laws of physics and build a strong running 350 with no compression and too much cam in it trying to push around nearly 2 tons of vehicle without a lot of gearing or converter......FWIW......

[track73]

I had an Elgin copy of the Summit 2800 cam in a low compression Pontiac 400 and it ran great. It had Very good low end torque.

[Jay S]

FWIW…The simulators like Stan gave a screen shot of generates symmetrical cam profiles. I have a similar program. If you want an idea of how a cam like a 702 or 703 Lunati act on a simulator like that retard the cam timing about 6* and run a sim and that will mimic how that Lunati cam will actually run, then run it again with the rated advance and take the highest HP and TQ from both. That is what I have found anyway, it’s because they have such long closing ramps on those cams, they are not symmetrical. The XE isn’t either, but the programs is closer on them than the Lunati Voodoo. The program represents the Summit cams pretty close though, they have some slight assymetric’s in their profile, not much compared to the others mentioned. Not that I have seen anyway. 2800 would drop in with the stock valve springs.

Even at .050” the Lunati voodoo cam shows a couple degrees of negative advance compared to the nose. It is one of the only flat tappet hydraulic profile that does that, degreeing the cam .050” down off the cam nose or from .050” off the base circle move the ICL quite a bit on those, just by measure from different points. Those also have 5* more seat timing than what is shown on the cam card, so they are much less aggressive than a Comp XE.

Comp’s XE is pretty hard to beat for building compression on something that is extremely low on compression. If you want the rough idle and big mid range push the XE’s do that pretty well. You could even go as big as a XE268 if it has a lower gear than 3.08s, more like a 3.73. With 3.08s you probably need that XE256 just like what the other guys mentioned.

I think the mid 70s 350 probably has more compression than 7.5, because if I recall right, it does not have the all the cylinder scallops and valve releifs other 350s have. It may have exh scallops on the bores? It is probably just under 8:1 if it has never been apart. If I was bothering with a cam swap I think I would use new valve springs and run the 702 Lunati, then advance it to 106. It would be a decent match up of street manors and top end power in a low compression 350 with a 4 speed and 3.08s. Probably no reason to go with the smaller 701 unless it was taller gears yet. The 702 would not care than much about the lower compression with a bit more advance.

[Cliff R]

I've witnessed a few dyno runs with Pontiac engines using iron heads and Comp XE cams. I've also had a good many customers (thousands actually) that used XE cams in their engine builds and many had dyno'd them. This would include a of other brands, Chevy, Olds, Buick, etc. They suck horribly in a Buick build but not sure why? I had discussions with Jim Weise years ago when he tried them in Buick builds and had to go back to the T/A cams he'd been using. Although they superficially showed some promise coming up thru the RPM range the Buick valve train didn't like them much and the engines went "dead" past 5000rpms and he even experienced rocker arm breakage. Power not only came right back no more parts breakage when he went back to T/A or factory cams in his engine builds.

Ya before you remind me I know that's not related to Pontiac stuff so I'll add this tid-bit about XE cams. I'm NOT fond of them and that's common knowledge on here. I can make a LOT more power with a similar size Crower cam in the same application without having to run a LOT of spring pressure or experiencing "lifter crash" at high RPM's. I'm never seeing as much power from Comp cams with iron heads, at least those with 30 degree intake seats. That shouldn't be surprising as the flat chamber floors and 30 degree seats thrive on low lift flow.

With all the bad rap I've given those cams over the years I have observed one success with them in a Pontiac engine and a few success stories here, so I'll add to them. It was a 455 set up for "stock appearing" drag racing. They "worked" the factory heads pretty hard (not even sure they were legal) and they used 45 degree intake seats. They also used super light valve train parts, titanium retainers, stamped steel rockers, etc. That engine cranked out pretty hefty power numbers and made nearly 90 MORE HP than a 455 another customer built using the same heads and XE cam a few years earlier.

I don't remember all the numbers or specific details from each engine other than they were both 455's, both used iron heads, about the same compression, same cam, factory intake, Q-jet and factory distributor. As good as the XE cam did in that one build I would still never use one. I do NOT like having to use a butt-load of spring pressure on a flat cam to keep things happy. It's just a personal thing, and why would I when I can make PLENTY of power with closer to stock spring loads and cams with a LOT less aggressive ramp profiles........FWIW.......

[Stan Weiss]

Originally Posted by Cliff R

Maybe on paper, but realize that dyno simulations do NOT tell us how well a cam will work once placed in service. Idle quality, vacuum production, throttle response, power right off idle, and good power and efficiency in the "normal" driving range is NOT well reflected by peak and average power numbers.

From what I've learned from actually doing this coming up on 50 years now is that compression is your friend with these things. Higher compression makes MORE power (torque) at every RPM, all else being equal, and it allows for larger cams with more seat timing and offsets losses in dynamic compression from going tighter with the LSA as well.

I've never built a Pontiac 350, but if I did the FIRST thing I would do was to obtain a late 60's set of small valve small chamber heads (grocery getter variety) like 1969 #46 castings. I'd do some good valve and seat work, better springs, screw in studs and mill them so my "little" 350 engine was closer to 10 to 1 compression than 7.5.

At that point I'd cam it similar to what I do with my 350 SBC builds (the exact specs depending on application/use of the vehicle). Then I'd enjoy closer to 1hp/CID or even a bit more, with good idle quality and street manners vs trying to defy the laws of physics and build a strong running 350 with no compression and too much cam in it trying to push around nearly 2 tons of vehicle without a lot of gearing or converter......FWIW......

Cliff,
I have never seen loses in dynamic (cranking) compression from tighter LSA. What I have seen is loses in idle vacuum from tighter LSA

Stan.

[Stan Weiss]

Originally Posted by Cliff R

I've witnessed a few dyno runs with Pontiac engines using iron heads and Comp XE cams. I've also had a good many customers (thousands actually) that used XE cams in their engine builds and many had dyno'd them. This would include a of other brands, Chevy, Olds, Buick, etc. They suck horribly in a Buick build but not sure why? I had discussions with Jim Weise years ago when he tried them in Buick builds and had to go back to the T/A cams he'd been using. Although they superficially showed some promise coming up thru the RPM range the Buick valve train didn't like them much and the engines went "dead" past 5000rpms and he even experienced rocker arm breakage. Power not only came right back no more parts breakage when he went back to T/A or factory cams in his engine builds.

Ya before you remind me I know that's not related to Pontiac stuff so I'll add this tid-bit about XE cams. I'm NOT fond of them and that's common knowledge on here. I can make a LOT more power with a similar size Crower cam in the same application without having to run a LOT of spring pressure or experiencing "lifter crash" at high RPM's. I'm never seeing as much power from Comp cams with iron heads, at least those with 30 degree intake seats. That shouldn't be surprising as the flat chamber floors and 30 degree seats thrive on low lift flow.

With all the bad rap I've given those cams over the years I have observed one success with them in a Pontiac engine and a few success stories here, so I'll add to them. It was a 455 set up for "stock appearing" drag racing. They "worked" the factory heads pretty hard (not even sure they were legal) and they used 45 degree intake seats. They also used super light valve train parts, titanium retainers, stamped steel rockers, etc. That engine cranked out pretty hefty power numbers and made nearly 90 MORE HP than a 455 another customer built using the same heads and XE cam a few years earlier.

I don't remember all the numbers or specific details from each engine other than they were both 455's, both used iron heads, about the same compression, same cam, factory intake, Q-jet and factory distributor. As good as the XE cam did in that one build I would still never use one. I do NOT like having to use a butt-load of spring pressure on a flat cam to keep things happy. It's just a personal thing, and why would I when I can make PLENTY of power with closer to stock spring loads and cams with a LOT less aggressive ramp profiles........FWIW.......

Cliff,
You answered your own question. Drag racing. Find someone running a "stock" Pontiac in NHRA and see what spring pressures they are running, along with tool steel lifters.

Stan

[Cliff R]

Wasn't talking about NHRA SA, the engine in question was going to be raced in factory Stock.

I'm well aware of what goes into "max effort" SA race engines as I build carbs (or used to) for them.

As far as cranking pressure from what I've seen here it's pretty much meaningless in the big scheme of things. My own engines have ranged from 150 psi to 200 and ALL of them made good vacuum at idle speed and excellent street manners.

What is HUGE in this deal is how much initial timing is required to get decent vacuum or the engine to even want to try to idle. Basic rule of thumb here is about 10-14 degrees. IF you aren't making at least 10" vacuum (hopefully more like 12-15") without running the timing clear off the scale at idle speed your engine isn't overly happy with the cam choice. I'm talking street engines here, not full race stuff.

At that point out come all the "crutch" fixes we get to read page after page of on here, my Forum, and just about every other Forum out there related to this hobby, when none of that would have been needed if the engine builder knew how to pick cams for the CID and compression ratio of these engines in the first place.........FWIW......

[Stan Weiss]

Originally Posted by Tim Corcoran

Based on the simulations that Stan provided the Voodoo 703 outperforms all other cams discussed.

JMO but with an automatic and stock converter and 3.08:1 or higher rear the 702 might be a better cam.

Stan

[Jay S]

Originally Posted by Stan Weiss

JMO but with an automatic and stock converter and 3.08:1 or higher rear the 702 might be a better cam.

Stan

X2

And the 702 will have decent street manors, between a XE256 and a XE262, even with very low compression. But it will hold on to power like a bigger XE 274, and does it without beating the snot out of the cam and valve terrain. Like Cliff, I am really not a fan of the XE’s cams either, but sometimes (like right now) that may the best of what’s available.

[Shiny]

Originally Posted by Stan Weiss

JMO but with an automatic and stock converter and 3.08:1 or higher rear the 702 might be a better cam.

Stan

Originally Posted by Jay S

X2

And the 702 will have decent street manors, between a XE256 and a XE262, even with very low compression. But it will hold on to power like a bigger XE 274, and does it without beating the snot out of the cam and valve terrain. Like Cliff, I am really not a fan of the XE’s cams either, but sometimes (like right now) that may the best of what’s available.

These threads often end up focusing on peak HP and/or peak torque, which makes sense to me for a race car.

But as these two comments suggest, not everyone wants to drive a race car.

What chart and/or metric is the best predictor of "street manners"?

Would the answer be a comparison of the torque curves or is it more about "area under a curve"? I'm pretty sure it isn't peak HP nor peak torque... but more about what happens at low rpm up to peak and where the peaks happen.

A long long long time ago, I had a 2-stroke 100cc Hodaka Super Rat. My room-mate had a 4-stroke Kawasaki 175. The Hodaka was useless at low rpm and was basically either "on or off". The Kawasaki had low end grunt and what I would call better "street manners".

I also owned a couple VW Jettas that were fun to drive. Granted there was no power, but the torque curves were so flat you often couldn't tell what gear you were in. To me, this is "street manners".

Maybe my definition is wrong... but I'm curious what others think "street manners" means and whether a simulation like Stan's can predict it?

[Steve C.]

Stan, Run a simulation for two hydraulic flat tappet cams that have the same .050" intake duration. Not in a 350 combo but a 455 combo.
I'm aware they are not rated at the same tappet lift but just for interest.
Lets look at a comparison of the torque curves or "area under a curve".

The ever popular Crower 60919 cam:

304 /316 ( or what ever seat duration they use these days )
231 / 240 @ .050
.470 / .470 lift
112 LSA / 106 ICL

A very popular UltraDyne Pontiac cam years ago:

288 / 296
231 / 239 .@ . 050
.485 / .507 lift
110 LSA / 104 ICL


.

[Jay S]

Without knowing what the rest of the combination is, I don’t know that you could gauge street manors very easy by looking at dyno chart. The gears and the weight of the car make a difference too.

Decent street manors to me can have some roughness to the idle, engine can have some lope sitting at a stop light, but clears up immediately off idle, with enough torque that on a manual transmission your not slipping the clutch to get the car rolling, and you don’t need to change gears to a lower gear to pull the load at part throttle. Or in a nut shell…can my wife drive it

I was mostly gauging the street manors in my comments by the cams overlap. The 702 is between the XE256 and XE262 for overlap. With 8:1 of less compression in a 350, much over 50* of overlap with those voodoo and XE cams the idle will start to get snotty, and loose quite a bit of bottom end power in trade for HP. If you were after stock type manors, those cams are probably one step big.

[PunchT37]

Looks like he`s got enough advise now to pick his cam for his combo. He has to decide what kind of street manners he can put up with.


Course, he ain`t ran any of these cams to find out.

[Stan Weiss]

Originally Posted by Steve C.

Stan, Run a simulation for two hydraulic flat tappet cams that have the same .050" intake duration. Not in a 350 combo but a 455 combo.
I'm aware they are not rated at the same tappet lift but just for interest.
Lets look at a comparison of the torque curves or "area under a curve".

The ever popular Crower 60919 cam:

304 /316 ( or what ever seat duration they use these days )
231 / 240 @ .050
.470 / .470 lift
112 LSA / 106 ICL

A very popular UltraDyne Pontiac cam years ago:

288 / 296
231 / 239 .@ . 050
.485 / .507 lift
110 LSA / 104 ICL


.

Steve,
What CR, head flow, exhaust manifolds or headers, intake dual plane or single plane?

Stan

[Steve C.]

Stan,
If possible create something typical that might be suitable for each cam, yet one that doesn't obviously favor one over the other.

I'm curious on the 'dyno' numbers presented and I no longer have any computer programs to run the two.
It's just a fwiw exercise since as already eluded to here it won't demonstrate a smoother idle, better off-idle response, superior low speed drivability and a broader power curve.




.

[Steve C.]

I should of edited the above post and removed "and a broader power curve."

That should not of been included as the 'dyno' numbers might indicate it.


.

[Stan Weiss]

Originally Posted by Steve C.

Stan, Run a simulation for two hydraulic flat tappet cams that have the same .050" intake duration. Not in a 350 combo but a 455 combo.
I'm aware they are not rated at the same tappet lift but just for interest.
Lets look at a comparison of the torque curves or "area under a curve".

The ever popular Crower 60919 cam:

304 /316 ( or what ever seat duration they use these days )
231 / 240 @ .050
.470 / .470 lift
112 LSA / 106 ICL

A very popular UltraDyne Pontiac cam years ago:

288 / 296
231 / 239 .@ . 050
.485 / .507 lift
110 LSA / 104 ICL


.

Steve,
I have file for the Crower 60919 which when I calculate duration from events is
290/300
231/240
.470/.470
112 LSA/ 108 ICL

It is from a few years ago and I don't remember where those number came from. Does anyone have a cam card for the Crower 60919 that they can post

Stan

[Steve C.]

Cam card in post #12, but noted it is old.

https://forums.maxperformanceinc.com...60919+cam+card

As discussed in that thread, and others related, Crowers numbers for the 60919 cam have varied over the years.

A few more here:

https://forums.maxperformanceinc.com...60919+cam+card

.