Comp Cams Camshaft 35-426-8

[AL427SBF]

Anyone running this cam in their SB? Curious on your experience with it, how the power comes on, a dyno chart would be awesome.
35-426-8 - Xtreme Energy

[blykins]

What size engine? What heads? What intake?

All of those things have a huge factor on what a camshaft does....

In a 408W with typical performance heads (AFR's, TFS, etc.) that cam would peak at about 5600-5800 rpm with some good bottom end.

In a 427W, it would be milder.

In something like a 331-347, it would be pretty peaky.

[AL427SBF]

Thanks Brent, just looking for a ballpark idea of the power band (RPM range).

Al DART 427w
Edelbrock Victor Jr Heads 70cc
Edelbrock Jr 1x4 Manifold
Willey's IMCA Spec 650 4BBL

[blykins]

I'm usually at around 240-242 at .050" for a 6000-6200 peak with a 427 and good flowing heads.

With your heads and that cam, you're probably looking at a 5500-5600 peak or so with good torque.

I built a 425w with Vic jr heads and a Vic jr intake with a similar cam and it made 484hp at 5400 with 500 lb ft. Basically out of the box parts. This was back in 2003.

You need more carb....

[AL427SBF]

Thanks Brent, sounds about right.

[vector1]

i have something similar coming from ed curtis, through lunati of course for a 408 with afr205 heads and vic jr. should be 236/247 on 111 range with .560 area lift, mild imo but should suit me. longevity of the springs and bottom end of the stock block was mentioned by him. length of the intake runners seemed to favor 5200-5500 range, and this is what i suggested to him. with this i'll use 1.6 rockers.

[blykins]

Why such a big duration split? Hardly ever necessary at all.... Kinda counterproductive to have a longer LSA but such a large degree of overlap.

[vector1]

one other thing he mentioned is setting the big valves down gently. the mj cam was 244/244 on 110 with .612 lift solid though for the 406 so it doesn't look like a lot of difference except for lift. i believe he has designed a lot of stuff so i will find out. i expect a really driveable broad power curve.... lot of hp down low.

[ERA Chas]

Originally Posted by blykins

Why such a big duration split? Hardly ever necessary at all.... Kinda counterproductive to have a longer LSA but such a large degree of overlap.

Possible the cam designer feels the AFR exhaust port needs help with greater duration? Especially with 'only' .560" lift??
That was the thinking (years ago) in my Ultradyne 244 / 255. And in my case that was right. The original iron MR exhaust was weak.

[blykins]

Did you try another cam?

The good sbf heads are not lacking on the exhaust side, unless you're making up for forced induction or nitrous.

I've never used more than an 8 deg split, even on drag race and road race FEs....that are supposed to be "exhaust compromised"...

What happens with a street engine is that you end up with a great deal of overlap.

I would rather match the lift to where the heads work the best then cut the split down to make it more streetable.

[ERA Chas]

No that was the only cam. But when I changed the heads to the much-improved Shelbys (with raised exhaust port floors and CNC ports and chambers) the motor still picked up. So I don't think the cam was limiting power. My exhaust side went from 180 to 230 with the head swap.
I also didn't mind the soft bottom end from the greater overlap on the street. I always drove aggressively and used RPM and lower gears. The way the motor worked above 3500 was exactly what I wanted.

[blykins]

Now, Claire, with your analytical mind, I'm sure that you understand that if you never tried another cam, you didn't have anything to compare against....

Tons of exhaust duration for street applications, has been a band-aid for a non-existing problem, IMO. The extra exhaust duration does have a different sound, which is what most guys go after though. That's why the Thumpr cams have so much of a following.....tons of exhaust duration (over 14° difference) with a short LSA. All show, no go. Less gas mileage, stinky idle, etc.

[vector1]

i think he's talkin to you brent.

[blykins]

Originally Posted by ducuptin001

cung du?c

Those are my thoughts as well.

[ERA Chas]

Originally Posted by blykins

Now, Claire, with your analytical mind, I'm sure that you understand that if you never tried another cam, you didn't have anything to compare against....

Tons of exhaust duration for street applications, has been a band-aid for a non-existing problem, IMO.

That's certainly true. But I never said I optimized my combination. Only improved it.
And with the original MR irons, the exhaust flow was a problem and the duration crutch certainly was a good thing (remember that was early '90's). My point was it didn't hurt the improved heads and didn't hurt my street driving because I tolerated anything to have the mid and top I had.
Now let me see---where did I put Barry's phone number...

[blykins]

Call Harold brookshire, he's the one that designed most of lunatis and bullet cams lobes.... ;-)

[vector1]

i was curious, so i pulled out the engine analyzer, and this is what it says--

using the above cams and my engine combo:

mj cam pk hp/tq 540/541, avg 416/476 10"vac at idle on 110lsa

ed cam pk hp/tq 533/533, avg 417/478 12.2"vac at idle on 111lsa

neither cam liked a tighter lsa, losing most power in the lower range, especially below 3700rpm, while gaining 1 or 2 hp/tq at the top.

the above was with 1.7 ratio on the mj cam and 1.6 on the ec cam. i put the 1.7 ratio in for the ec cam and it didn't like it, showing:

ed cam pk hp/tq 514/537, avg 405/469 11.9"vac at idle

using the 1.7 on the exhaust didn't have any effect.

i was surprised, i knew i was giving up pk power with the ec cam, but the avg was the same or better. this was in the 3000-6150rpm range btw for both cams. the 1.7 ratio really killed the top end of the ec cam.

[blykins]

I don't have much confidence in EA or DD2k, but if those numbers were truly representative, I would rather have the first cam....more peak and similar averages.

It shows how efficient it is to make more horsepower with a straight pattern. You can advance the ICL and get the 2 inches of vacuum back plus more average power.

I can't remember if you said the jones cam was a solid or not, but changing it to a hydraulic would yield even more favorable results.

I don't agree with the rocker ratio results....that has never been an actual trend unless the head flow dictated it.

[vector1]

so i put the comp cams data in to see how it faired on the 408, it was down on pk hp/tq again, but picked up avg.

pk 528/527, avg 418/480, idle vac 12.7. it was real nice below the 3700rpm mark besting the other two cams, so it depends where you want your power.

seems below the 3700 mark is where the reversion comes into play on this program.

[blykins]

I did some playing as well, I have EA 3.0.....

FWIW...

With a custom hydraulic roller using Comp lobes, 236/240, .630/.630, 110/104, it shows an increase of 13 hp and 14 lb-ft at peak. Averages went up 11 hp and 13 lb-ft.

Again, just a simulator, but in reality, I just don't see how taking valve lift away and adding a ton of overlap would help performance at all.

I see a lot of crazy cam recommendations out there. One guy called and bought a cam from me a couple of weeks ago because he had R&R'd the lifters and saw that the lifters were wearing the cam lobes. This had been the 2nd or 3rd cam that he had got from the same company, and each time he had issues with it. However, the common trend was that the grinder had recommended too much duration, way short on lift, WAY tight of LSA for a street car (104 LSA), and then on top of all of that, the spring pressures he had recommended were about 120 lbs seat and like 350 lbs open. The lifters were lofting, valves were bouncing, and everything was just simply jacked up. Supposedly, this cam grinder was a Ford guru as well....