It's time to do something about the 541 rolling over and playing dead at 5100 rpm.
Opinions were pretty firm on the valve springs being insufficient so that's being addressed.

The elephant in the room is that monstrosity of an intake. It was a fun science project 17 years ago and it worked great on my 440. There is some question about it being able to feed 541 inches at any appreciable RPM.

Being the data nerd that I am, I start asking myself too many questions that I can't find answers to. It's time to call in the pros.

The boys over at Wilson Manifolds have sent me a form to complete. I'll fill it out and include a plethora of photos of the intake, inside and out. Luckily, I still have some photos of the original build. They'll tell me if it's viable, salvageable, or a train wreck that needs to go away. I'm sure they've got all kinds of wonderful shiny things that are just perfect for what the motor needs but this thing doesn't need a $5000 intake.
I'm not afraid to throw a little money at it but the packaging requirements dictate an induction system that is no taller than what I currently have. There's plenty of cash in the engine already. It kinda makes sense to drop a bit more if it'll make it happier

I’m not an expert, but I don’t think you’re going to get much more RPM more out of that with a standard port window. Online calculator says you’re at about 575 FPS at 5100 RPM using a standard port gasket CSA.

I think the valve springs needed to be addressed, so glad you’re taking care of that.

It will be interesting to hear Wilson’s take on the manifold, as it pertains to the upper end of the power band.

However, unless there can be gains made to the upper rpm area of the curve that don’t negatively impact what the curve looks like down low....... then I’m not so sure I’d venture down that path......... in light of what the overall scope of the build is.

I wanted to get their take on the runner size, current entry radius, and their take on opening the runners to meet the ports.
Sliding a bore scope down the runners tells me the head is larger than the runner by a fair margin. I knew that because the ports are significantly larger than the gasket windows. The gasket does not overhang the intake. That's a good indication that there's volume to be had.

Now, this intake was designed to feed an engine nearly 25% smaller than what it's sitting on. The low operating RPM range tells me I want to keep moderate volume ports but the extra cubic inches tells me I should increase that a bit. This is where I get into that tricky balancing act. Again. The added port volume would surely add more power up top but will it lose torque trying to get there? Honestly, I have a wee bit of torque to spare but torque was one of the goals of the build.

The part that is really hard to test out of the car is the part throttle low rpm performance. Again, there's no such thing as a soft bottom end on a 541 but I don't need to push that theory. The throttle body moves enough air to make a Dominator blush so the progressive linkage will be handy. The cavern it feeds is pretty big, too. Lots of room for stagnant air to lull about.

After a detailed examination I'm sure there's power to be found inside this fairly crude intake. The oddball shape is a necessity for hood clearance as well as fitting around the other engine bits and accessories. Still, it's not the best example of a fabricobbled intake.

The engine is scaled up so it make sense to increase the size of other bits accordingly. How much of an increase it will take to cross the line from productive to non-productive in this situation remains to be seen.


I'm starting to think you drag racers have it easy. Stuff in as much as it'll take and screw street manners is sure starting to sound good about right now.

The combination of modest compression and cam timing, combined with a small port cross section(relative to the displacement), doesn’t seem like something that would lend itself to an extended upper rpm power curve.

Assuming the valvetrain was 100% stable to say 62-6300, I don’t think the engine would peak above 5800-ish even if it had a Super Victor and a Dominator on it.

But....... there would be only one way to know for sure.

And then, what would the bottom end of the curve look like with the SV/4500 in place?

However, that’s not to say that as it was on the dyno you didn’t have two issues contributing to the poor upper rpm power.
Valve springs.........and possibly the manifolds tuned rpm.
If the curve would have hung on even just a few rpm longer, it could have been worth 20+ hp........ and even more in the 5500 range.

Are using OEM small ports? And what intake? I am sorry I do not keep track....

If you want to replace that intake with similar configuration, what about Edelbrock 7144?

Shop around on deciding who to use to make your new custom EFI manifold.
I'm in the middle of deciding on who to use on making me a centrifugal blower manifold with a direct port EFI system, I ended up using Hogans Manifolds after talking to every custom manifold maker I could for making me a B1-MC headed BB Mopar blower manifold including Wilsons

I'm using ported Edelbrock heads and my one-off used-to-be Weiand tunnel ram converted to EFI.

i doubt that intake is the issue. my 543 just did 530 / 590 tq at the wheels on pump gas through a 4150 as cast (its rough too) edelbrock intake manifold.

5100 is probably keeping your block alive. I'd swap in some 2.73s out back and let it take advantage of all that torque down low.

My last 440 made far more torque and did so for more than a decade with a garbage build.
Rpm kills more blocks than torque.

My goal was a usable 5500 rpm. The combo would likely be done by then anyway.

I’m confident that all it would take to allow the truly usable powerband of that combo to extend to 5500+ is proper valvetrain control.

There would have to be some really odd wave tuning going on with the manifold for it to be a big problem in that rpm range(which is not out of the realm of possibility).

But.......as I often say....... only one way to know for sure.

It's only money.

But, I might learn a thing or two. Wilson has pics of the intake inside and out. The guy I was speaking to agreed that it was an unusual build. He was going to get together with some of the others and see what they can come up with. I told them the intake was a blank canvas to mod but the overall height was fixed and position/angle of the throttle body could not change.

As for the springs, I tried to make some calls over the last couple days but simply could not find the time due to work load. I'm curious about the spring pressure the Gatorman lifters can take at 5500-5800 rpm.

Considering the 925 springs are currently installed, is it more likely that pressure at the seat or over the nose is more critical? Maybe if I could find something around 140 seat and 385 over the nose it would sole the problem without being too hard on the lifters.

You'll do far more damage with light springs/losing control/smashing the hell out of everything than just running the right closed/open pressures.

I don't see why the lifter would care. Many seem concerned about spring pressures and the lifter but disregard rocker ratio? (which would greatly change what the lifter -sees-)

If it was mine I would run 165 seat and 400-420 over the nose with the smallest diameter dual spring I could find to achieve that. (and stiff/large diameter pushrods if they will fit) JMO

It's hydraulic. Put the whammy on those lifters and they'll get rather unhappy. I was hoping to stay under 400 in the interest of longevity (street motor) and component survival. I've got 1.5 Comp roller rockers upstairs.

“If” the primary cause of the horsepower nose dive at 5100 is in fact valvetrain related(which we don’t really know because we haven’t been provided with what the actual spring installed height is....... and we don’t have any air flow data to look at), then the springs are just set up way too light imo.
The correct spring set up incorrectly is just as bad as using the wrong springs.

I’m confident that if the valvetrain were set up with springs providing closed/open pressures in the 150-160/400-420 range, the valvetrain would hang on til at least around 5800-6000 or so.

I had a very mild 505 on the dyno a few years ago that had everything air flow related “too small”.
Modest CR, rpm heads with a minor blend, original Torker intake, 850vs carb, 1-7/8x3 headers....... and a .480” lift HFT cam.
Made peak hp at 5100....... with the air flow numbers showing the valvetrain started to lose control at about 5500.
I was making pulls to 5700, and even though you could see the airflow numbers start to back up, and the VE numbers start to tank....... there were no sounds of any distress coming from the motor.

The power numbers for the last few lines on the dyno sheet of the 541 drop off quite a bit faster than those on the sheet for the above mentioned 505.
The 505 lost 5.5%(28hp) from its peak to 500rpm higher(5100 to 5600), whereas the 541 lost 13%(69hp) from its peak to 500rpm higher(4900-5400).
Since I know the 505 was having some valvetrain control issues........ I feel like they were happening to a more severe degree with the 541.........however that’s based on somewhat incomplete data.

I'm pretty sure these springs were a bad decision.

I popped one off tonight and threw a height gauge in there.I was rewarded with a reading of 1.877" installed height. Spring is advertised as 395 lb with 111 seat at 1.9 installed. This gives me roughly 121 lb seat and 353lb over the nose.

Not gonna cut it.


A big thanks to Comp for that recommendation!

I dug around a bit tonight and came up with the following options:

Comp 26055 beehive installed 1.90, seat 160 nose 385

Comp 7228 conical installed 1.8, seat 136 nose 396

Manley 221432 NexTek oval track/endurance installed 1.9, seat 150 nose 406

Isky 8005SP High Endurance installed 1.875, seat 150 nose 408

Isky 8205Plus Endurance Plus Extreme installed 1.9, seat 150 nose 415


I don't have any experience with any of those springs but they all fall in a usable range. Which of these would live a happy life on the street?

Are your lifters hydraulic rollers or standard flat tappet .904 diameter anti pump lifters?

PAC1220: 150lb seat at 1.880 and should be about right for your open pressure. S/F....Ken M