[Cliff R]

Stan, the "split dyno" shows us how much more power was made going to a larger camshaft. It's an apples to apples comparison as only ONE change was made, well actually two changes as they swapped back to the Q-jet for the final dyno runs to get those numbers.

What your dyno sims and on paper comparisons don't tell you is that the larger camshaft allowed them to run optimum timing which accounts for a big part of the power increase. More timing also resulted in better idle quality at the same time offsetting the added duration and overlap from the larger camshaft.

The lesson to be learned here as I've pointed out many times over the years is picking a "small" cam for a 455 engine build on a tight LSA. Some may get away with it but for sure you are leaving a LOT of power on the table and can also run into issues trying to manage pump gas.

I don't know about you but for sure I'll take the 9.3 to 1 compression 455 with factory iron heads that idles better and makes 514hp vs 428hp!...........

[Stan Weiss]

I don't need to look at dyno sims just your dyno sheets. The fact is that the bigger cam let the engine ingest more fuel (BTUs). Maybe a graph of the 2 fuel usage will show it better than just numbers on a dyno sheet.

Stan

PS Let me add that there also was an improvement in how well it did use that fuel. BSFC.

[jhein]

Back to the OPs original question, what's the recipe for a 400 with 62 heads to get as lumpy of an idle as possible while still having a streetable motor?

[Cliff R]

The fact is that the bigger cam made more power at every RPM, and allowed the use of pump fuel without detonation with optimum ignition timing.


I suppose since it made over 90 more HP and 40 ft lbs torque plus more average power and improved idle quality it would be considered by most to be a better choice for this engine........

[Cliff R]

"Any one running the 744 roller Comp Cam Butler is selling? Butler suggested this cam for a 400 build I am working on. 30 over, Torker II, Holley 750, headers,-17cc pistons, 3:08 and currently a stock convertor."

17cc dished pistons with 62 heads will put the compression WAY too low for a "744" size camshaft

17cc plus 75cc puts the compression in the low 8 to 1 range or basically no more than a later 400 with 6X-4 heads on it. The biggest cam I'd use with that deal is the Crower 60240, 210/221/112LSA. More cam than that up against a stock converter will be a complete "turd" everyplace........IMHO......

[Steve C.]

If one wanted to use a cam with the duration Cliff mentions. A similar Lunati Voodoo Hydraulic Roller Cam ?

Similar to the Crower 60240 but with shorter seat timing to help with the lower compression. That and the additional valve lift, a very positive thing. Presuming the heads will accept the additional valve lift.

https://butlerperformance.com/i-2445...tegory:1234836

If one prescribes to the cam designer Harvey Crane and his "CAM PROFILE INTENSITY" material it was his personal opinion, the smaller the intensity numbers measure, the performance will increase.
His material was published many years ago, but even then he stated recent advancements in design technology have made it possible to open and close the valves with more area under the lift curve. By doing so, engine efficiency is improved because the valves spend less time at very low lift. Further he stated In practical terms, if two cams with similar lobe designs have the same duration at .050" lift, maximum torque and horsepower will be almost identical. However, the cam with the smaller intensity figure will have a smoother idle, better off-idle response, superior low speed drivability and a broader power curve.

The Crower cam has a 60 intensity number
The Lunati with a 51 intensity number
One caveat would be IF the two cams were rated at the same tappet lift for the seat timing.


.

[Stan Weiss]

Originally Posted by Cliff R

"Any one running the 744 roller Comp Cam Butler is selling? Butler suggested this cam for a 400 build I am working on. 30 over, Torker II, Holley 750, headers,-17cc pistons, 3:08 and currently a stock convertor."

17cc dished pistons with 62 heads will put the compression WAY too low for a "744" size camshaft

17cc plus 75cc puts the compression in the low 8 to 1 range or basically no more than a later 400 with 6X-4 heads on it. The biggest cam I'd use with that deal is the Crower 60240, 210/221/112LSA. More cam than that up against a stock converter will be a complete "turd" everyplace........IMHO......

Can I ask what calculator you are using and what other numbers? I get about 8.9:1 CR.

Stan

[Steve C.]

And if one wanted to use the "small" amount of .050" duration and stay with a hyd flat tappet cam and similar to the Crower 60240 at .050".
Lunati makes a HFT Voodoo lobe:

10510701
256 / 262
213 / 210
.455"/ .468" lift
112 LSA

Again, with a smaller intensity number. However a pretty small cam, Lunati suggests a good choice for 350-389 c.i. daily driven street performance vehicle.

[Stan Weiss]

Originally Posted by Steve C.

And if one wanted to use the "small" amount of .050" duration and stay with a hyd flat tappet cam and similar to the Crower 60240 at .050".
Lunati makes a HFT Voodoo lobe:

10510701
256 / 262
213 / 210 <<<< Should be 219
.455"/ .468" lift
112 LSA

Again, with a smaller intensity number. However a pretty small cam, Lunati suggests a good choice for 350-389 c.i. daily driven street performance vehicle.

Steve,
You were one key too far over.

Stan

[Karl Rich]

Originally Posted by Cliff R

"Any one running the 744 roller Comp Cam Butler is selling? Butler suggested this cam for a 400 build I am working on. 30 over, Torker II, Holley 750, headers,-17cc pistons, 3:08 and currently a stock convertor."

17cc dished pistons with 62 heads will put the compression WAY too low for a "744" size camshaft

17cc plus 75cc puts the compression in the low 8 to 1 range or basically no more than a later 400 with 6X-4 heads on it. The biggest cam I'd use with that deal is the Crower 60240, 210/221/112LSA. More cam than that up against a stock converter will be a complete "turd" everyplace........IMHO......

The 744 cam and -17 cc pistons were suggested by Butler, currently have an 068 cam and the 8 relief builders pistons .030 over. There was nothing wrong with the motor when I tore it down just wonted to see what I was working with and to freshen it up with new bearing, rings and seals and step up the cam to a roller. I really like the aggressive choppy sound “Hot for teacher” but it sounds like I will not get it with the 744 cam. Damn my head is 😵*💫. Don’t know which cam to go with to get what I won’t.

[Cliff R]

"Can I ask what calculator you are using and what other numbers? I get about 8.9:1 CR."

Didn't use one Stan as I didn't have ALL the information, head gasket thickness, measured size of the combustion chambers, distance the pistons are below the deck at TDC, etc?

It's going to be in the 8 to 1 range and not enough compression for "744" size camshafts especially if it's up against a stock converter........IMHO.....

[Steve C.]

Steve,
You were one key too far over.

Thanks. BRAIN fade


.

[jhein]

Originally Posted by Karl Rich

The 744 cam and -17 cc pistons were suggested by Butler, currently have an 068 cam and the 8 relief builders pistons .030 over. There was nothing wrong with the motor when I tore it down just wonted to see what I was working with and to freshen it up with new bearing, rings and seals and step up the cam to a roller. I really like the aggressive choppy sound “Hot for teacher” but it sounds like I will not get it with the 744 cam. Damn my head is 😵*💫. Don’t know which cam to go with to get what I won’t.

Since you have it all torn down, sounds like you need a new set of pistons to bump up the CR then get a bigger cam. I love that "hot for teacher" sound too but I don't think you can get that in a reasonable street motor, probably 041-ish is the best you can do. No matter what, it'll be better than the 068.

[Jay S]

Originally Posted by Karl Rich

The 744 cam and -17 cc pistons were suggested by Butler, currently have an 068 cam and the 8 relief builders pistons .030 over. There was nothing wrong with the motor when I tore it down just wonted to see what I was working with and to freshen it up with new bearing, rings and seals and step up the cam to a roller. I really like the aggressive choppy sound “Hot for teacher” but it sounds like I will not get it with the 744 cam. Damn my head is ��*��. Don’t know which cam to go with to get what I won’t.

Are Butler’s having you changing out the connecting rods to Forged and then rebalancing the rotating assembly along with lowering the compression?

The .45” lift cam seems like questionable pick for someone that is taking time to port their heads.

One of the good attributes of roller cams versus typical hyd flat tappets is the roller can have more duration and curtain area at and beyond .2” lift, which is where the fastest piston speeds occur. That helps the roller set ups make more average power and tends to clean up the idle up against a HFT cam for the same .050” durations. When the lift is limited to .45” like Butlers Ram Air series 744 HR grind (without a dwell nose grind) it reigns in the duration and curtain area compared to a cam such as that XR276. So even though XR276 has more overlap, it can likely tolerate more overlap and still have a smoother idle largely do to that extra duration at and above .2” lift.

Bulter’s do not list much for specs for the ram air series, but given what little specs are given, it is certainly not going to be a very aggressive idle. Likely very similar to the Summit 2802 that was mentioned. The Bulter 744 HR appears like it would be easy on parts, and would work well with stock heads, but it does not appear to be a performance oriented cam with ported heads and headers. Especially when there are flat tappets that would out perform it in a engine with some mods.

In a 400 around 9:1 SCR, with the 3.08 gears and a mild converter, ported heads and headers, the XR276 with the 110 LSA would be a better choice IMHO, it would have a more aggressive idle but not terrible more aggressive. If you want it to really run and use your heads consider jumping up to the bigger 282,288 Butler custom 112LSA XR grind and try to get the compression into the mid to upper nines.

[Cliff R]

"That helps the roller set ups make more average power and tends to clean up the idle up against a HFT cam for the same .050” durations"

+2

I've back to back tested cams on the dyno, flat tappet solid, flat hydraulic and hydraulic roller. Comparing the flat hydraulic cam I tested with a very well chosen HR cam didn't make nearly the power increase expected, but for sure it idled better and produced more average power. Peak numbers only increased by 3hp/4ft lbs torque, but that doesn't tell the whole story. Vacuum went from 12" to 13.5", and I was running Rhoads lifters on the flat cam, without them vacuum was down around 10". The reason we didn't see a lot more power was because of the seat timing. The flat cam sported 304/314 degrees vs 284/296 for the HR cam. I also had 1.73 ratio rockers on the flat cam.

There are other advantages to the roller that you don't see on the dyno or on paper. At the track the car ran 11.70-11.85 with the flat cam for most runs depending on DA and track conditions. With the roller it picked up a solid tenth or so and most runs were in the 11.60-11.75 range and we saw more MPH. Best run with the flat cam was 11.64 @ 114mph. The HR cam ran 11.52 @ just under 117mph, clearly showing the advantages of the roller design in freeing up the engine a bit to rev quicker and not drag it down as much across the RPM range.

As much as I dislike the XR276HR cam in 455 builds I also agree that it would be OK in a 400 build with moderate compression. Even so the cam below is a better choice everywhere for a mild 400 build with higher compression. It works fine in a 455 with lower compression as well. It's a HR cam without a lot of lift and doesn't take a butt-load of spring pressure either............

[mkpontiac]

In considering octane resistance for the 281/287 @0.006 with 230/236 @0.050 HR cam recommended vs an XE274 HFT are the greatest contributing factors the 112 vs 110 LSA and the 112 ICL vs the 106 ICL? The 7° more advertised duration for the HR seems less significant. Am I understanding this correctly?
Mark

[i82much]

when i built mine i thought i wanted a fast car. turns out what i really wanted was to idle up our steep driveway in first gear without slipping the clutch.

[Stan Weiss]

Originally Posted by mkpontiac

In considering octane resistance for the 281/287 @0.006 with 230/236 @0.050 HR cam recommended vs an XE274 HFT are the greatest contributing factors the 112 vs 110 LSA and the 112 ICL vs the 106 ICL? The 7° more advertised duration for the HR seems less significant. Am I understanding this correctly?
Mark

JMO Where you have IVC ABDC is the most significant factor. If you change the LSA still using the same lobes and set the ICL the same there is basically no change in octane resistance

Stan

[Cliff R]

The XE274 cam is smaller and tighter LSA. Installed at 106 ICL you it will require higher octane than the larger HR cam with the ICL set at 108 degrees. Tighter LSA narrows the power curve and it will make peak torque earlier. When the timing events happens slower cylinder filling is better, so higher dynamic compression and at the same time higher octane needed to run the same tune.

I've witnessed dyno runs with the XE274 cam in 455 builds with iron heads and not impressed. The last one I saw on the dyno made a whopping 412HP at 4900rpm's and torque was clear down to 414ft lbs at 4900rpms. Peak torque spiked pretty high and was over 500ft lbs at 3200rpm's......a "recipe" for detonation for sure..........IMHO......

It is a completely different animal in a 400 build however as the shorter stroke has it working a lot better. I've seen a few folks do well with them in 400 builds, even so I run as fast and as far away from Comp's XE flat lobes as I can. They require too much spring pressure for my liking and seating velocities are quick. Not uncommon at all to have owner complaints of a noisy valve train and I've seen so many with lobe failures I've lost count.........

[Stan Weiss]

While I don't have a Cam Doctor. I have over the years had a number of people who have been willing to share their Cam Doctor files with me. This is a Comp XEH 3192 lobe. It is very clear that it has a small amount of asymmetry on the closing side. This is done to slow down the seating velocity. Note seating velocity is not only a function of cam design but also RPM.

Stan