[SD455DJ]

I'm quite certain that Mac McKeller said they simply added more "dwell", or iron to the 068 cam lobe ramps to get more duration, but not increase the lobe height of .281" thereby creating the squared-shoulder appearance of the lobes compared to milder cam lobes. Mac said this wasn't his best idea for a street HFT cam since it needed higher spring pressures to control the lifter flying off the shoulders at higher rpm's and crashing back down in the back side of the lobe.

The SD455 motor utilized 1.812" installed height springs like the RAIV's with enough pressure to control the harmonics of the 744/Y cam.

Spring info is on page 11, not 13 in the H-O manual.

Dennis

[b-man]

.....a 541596 421 Super Duty McKellar #10 solid lifter camshaft.

The valve timing specs are pretty much identical to the RAIV '041' hydraulic lifter cam with 308/320 advertised duration, but with lower valve lift values of .445" intake and .447" exhaust using 1.65 rocker arms.

Just thought I'd post this as a visual so others might better understand what some of the factory 'square lobe' cams looked like.

Intake lobe.



Exhaust lobe.

[Formulajones]

Originally Posted by 69Farburd

I made a sound clip with my IPhone, but can't figure how to attach it here.

I'll pm you my email if that makes it any easier. If you have the time to try it I'd appreciate it.
Thanks.

[Will]

Originally Posted by Formulajones

What kind of lash do you run with that? The lash, depending on how much, will play a roll in taming that cam down a bit in terms of duration, lift, overlap.
Which actually may help that cam work nicely in your 4" stroke 428-ish combo.

...
Your solid lifter RAIV cam would be more of a permanent situation similar to the Rhoads lifter deal, but would still likely have more HP/rpm capability up top. Just thinking out loud here.

Keep in mind it was a solid ROLLER, not SFT, so less seat timing and overlap with more aggressive valve opening rates than an SFT would have had.

It's been awhile, but if memory serves I ran .012"/.014" lash. Best shift points with my combo were right about 5400 RPM.

From what everyone is saying, that 041 roller was a bit more "radical" than the 2802, which makes sense as it had 6 more degrees duration and a bit more valve lift.

[SD455DJ]

B-man, That is the ultimate Pontiac square lobe I'm talking about. The 744 and Y cams aren't that severe, but certainly more noticeable compared to the 066/067/068 cam lobes and even the 041 'T' RAIV cam! You can visualize the additional material needed to make it a higher lift lobe like the RAIV cam and become more 'egg' shaped.

Thanks for posting those pics (I also have an NOS #10 cam too).

Dennis

[SD455DJ]

Originally Posted by Formulajones

Interesting indeed. From your comments it sounds as though the 2802 would be a much better choice over the 744. Sure looks as though it worked very well in your 455. I wouldn't have expected that to get so close to 400 hp.

I'd be very interested in what Dan finds with his camshaft charting. I hope he posts some results.

Formulajones, If it had large valve heads with 25 cfm greater flow, it would have been in the 420 hp/540 lbft range. I revisited the dyno sheet and the 390 hp was achieved at 4500 to 4800 rpm and the 512 lbft torque at 3400 rpm, however the 500(+) lbft value was from 2700 to 3900 rpm, 450(+) lbft from 2500 to 4500 rpm. If you figure shift points at 10% above the peak rpm point of 4800 rpm + 480 rpm = 5280 rpm +/-. It has tremendous torque everywhere and needs sticky tires to keep the rear tires where they belong on the road (behind the fronts, lol).

Dennis

[SD455DJ]

Originally Posted by Formulajones

What Dan reveals will probably answer all these questions and more.

OK, here are the results of Dan's cam investigation that have been converted to a numerical value that we call Potential Performance Intensity, or PPI value. Basically it is the flow in cfm of valve lift points at 0.050" increments (also starting at 0.050") through peak valve lift (so measured at 0.050"/0.100"/0.150"/0.200"/0.250"/0.300"/0.350"/0.400"/etc. So, the values don't really mean anything except to be able to compare values from one cam to the next on a std. large valve D-port head. CFM flow at each lift increment was simply multiplied by the corresponding duration and added up for both intake and exhaust values, then divided by 1000 to arrive at the PPI value of the cam. Simple, right? This doesn't have any correlation to proper engineering, so all you mechanical and physics people, cut us a little slack and don't roll your eyes too much.

OEM Cam PPI values: 066 @ 199; 067 @ 205; 068 @ 221; 744/Y @ 244; 041 @ 259 (252 @ 0.400" lift)

Aftermarket Cam PPI Values: 2800 @ 224; 2801 @ 243; 2802 @ 250; Old Melling SPC-3 @ 246; New Melling SPC-3 @ 227

Lowest to highest PPI ranking:
OEM 066 @ 199
OEM 067 @ 205
OEM 068 @ 221
Summit 2800 @ 224
New Melling SPC-3 @ 227
Summit 2801 @ 243
OEM 744 @ 244
Old Melling SPC-3 @ 246
Summit 2802 @ 250
OEM 041 @ 259

Observations: 1) The new Melling SPC-3 Cam (actually discontinued recently) is fairly equal to the OEM 068 cam and Summit 2800 (221/224/227 PPI's not respectively); 2) the old Melling SPC-3, Summit 2801, and OEM 744/Y cams are fairly equal (243/244/246 PPI's not respectively); 3) the OEM 041 cam's PPI would be greater if we used the RAIV head cfm flow values and 1.65 rockers...guessing maybe a PPI value of 280-ish.

Well, take it for what it's worth and enjoy. We had fun playing with this.

Dennis

[SD455DJ]

Another observation is the Summit 2802 has a slightly higher PPI value than the old Melling SPC-3/OEM 744/Y (250 vs. 244/246) and not too far above the 2801 rated at 243 PPI...interesting.

Dennis

[SD455DJ]

Originally Posted by Will

Has anyone run the 2802 in a 455? If so, what was the rest of the combo and what did you think of it?

Will, I will say that after I did this I wish my compression was closer to 9.5, or I ran the RAIV cam with Rhodes lifters with the current heads & compression.

Dennis

[Formulajones]

That's interesting Dennis. Sure makes that 2802 look pretty good from that standpoint based off the numbers.

Really looks like it works nice in your 455. I'm surprised at how well that engine did with small valve heads.

Your comment to Will.....are you having some detonation issues?

[SD455DJ]

Originally Posted by Formulajones

Your comment to Will.....are you having some detonation issues?

Yes, if I get into the secondaries on a hot summer day it will complain with 93 octane, but will drive fine without rattling in normal stop and go driving and. I can always add race gas, but I hate the hassle. In the cooler spring and fall (under 80 degrees, it'll run fine at wot).

Dennis

[Frank R]

For comparative purposes do you have a PPI value for the Crower 60243?

[Will]

Originally Posted by SD455DJ

Will, I will say that after I did this I wish my compression was closer to 9.5, or I ran the RAIV cam with Rhodes lifters with the current heads & compression.

Dennis

Thanks Dennis.

The compression ratio with what I'm doing should end up around 9.2-9.5 depending on how far the pistons are down in the holes.

I don't think the RAIV makes sense for this engine. I'm not going to port the heads. They've been gasket matched and the bowls cleaned up/blended already and I don't want to put any more work into them. I'll probably sell them at some point. As mentioned, this is just a holdover engine until I can get around to putting together the 4" stroke engine I really want, so I want to find a cheap shelf cam to throw in it that will work well and I want to keep the shift point at 5K or lower due to it being a stock bottom end with unknown mileage. I was thinking of the Crower 60916 or 60242 also, but they're just a tad smaller and more expensive though I do think the 112 LSAs would be better for boosting midrange power and keeping the shift point lower.

[SD455DJ]

Will, with 9.2 to 9.5 compression the 2802 would be a great choice. Make sure you get valve springs that can accommodate the higher lift (.466"/.488"). You only need 120 lbs seat pressure and 275 lbs. At .500" lift. You will only need to rev to 5200 rpm which is perfect for the 455.

Dennis

[SD455DJ]

Originally Posted by Frank R

For comparative purposes do you have a PPI value for the Crower 60243?

Frank, sorry, we only measured the cams we had lying around, but if the specs are similar to one of the ones we tested, that should get you close. I'll look into it and post a little bit later tonight.

Dennis

[SD455DJ]

Frank, I see the 60243 has 228/235 degrees duration at 0.050" and .480"/.490" lift, so rough interpolation would put it somewhere in between the 2802 and the RAIV cams.

Dennis

[Will]

Originally Posted by SD455DJ

Will, with 9.2 to 9.5 compression the 2802 would be a great choice. Make sure you get valve springs that can accommodate the higher lift (.466"/.488"). You only need 120 lbs seat pressure and 275 lbs. At .500" lift. You will only need to rev to 5200 rpm which is perfect for the 455.

Dennis

Yep. Per my OP, the heads are good to go with Crower 68404 springs installed. They were previously on a 400 that was running a Comp Magnum 270 cam. CR on that engine was only about 8.5 and it was a bit doggy down low. Good thing it was in a 4-speed car with 3.73s.

[Formulajones]

Originally Posted by SD455DJ

Yes, if I get into the secondaries on a hot summer day it will complain with 93 octane, but will drive fine without rattling in normal stop and go driving and. I can always add race gas, but I hate the hassle. In the cooler spring and fall (under 80 degrees, it'll run fine at wot).

Dennis

Thanks Dennis,

What kind of timing did you find it liked on the dyno with those numbers you posted?
Wondering if you found what I usually experience with dyno time on an engine that is on the "edge" octane wise. Usually what it runs best with on the dyno is more than what I wind up with in the car because the operating conditions are so different.

[SD455DJ]

Originally Posted by Formulajones

Thanks Dennis,

What kind of timing did you find it liked on the dyno with those numbers you posted?
Wondering if you found what I usually experience with dyno time on an engine that is on the "edge" octane wise. Usually what it runs best with on the dyno is more than what I wind up with in the car because the operating conditions are so different.

FJ, Yes, dyno room conditions are ideal compared to underhood where it is much hotter. On the dyno we ran 34 degrees total as well as on the street. We had a knock sensor and light on the motor and it went off on a run at 36 total (93 octane). If I experience any detonation problems or get some crap gas, I'll simply back off the timing a few degrees . I have a set of 6X-8's that I may substitute someday to get the compression down to 9.5-ish and not have to worry about the tune all the time. The performance should be comparable with the bigger valves greater flow (210 vs. 190 cfm) to offset the .5 drop in compression.

Dennis

[Formulajones]

Thanks Dennis,
I've been down that road with engines that are on the edge so I understand what you're trying to do.
Based on what you are experiencing with a 455, it seems that 2802 might work pretty good with pump gas 10:1 engines that are say,,,,400-428 ci?? Since the cam should act a little bigger in those engines.

I'm just thinking out loud, with the 10:1 455's, the go to camshaft seems to be the RAIV stick with rhoads lifters to tame down the low speed characteristics, then it probably wouldn't be a stretch to think the 2802 could work in the same way for the smaller 400-428's without being too radical?? Just a thought.