Slow after 5000rpm

[Budnicks]

hard to diagnose over the -www-
no video or pertinent info

just spit-balling here like most of US, guess

nosing over after 5,000 rpm

sounds like lean W-O-T to me

or valve float possibly
or maybe a little too much overall (or initial) timing

you need an accurate fuel pressure gauge & see what it's doing
don't just go by an AFR gauge either, that's spent gas

New mechanical pump,
what kind ?
what PSI ?
(you really need to know)
or float levels possibly also or an obstruction/choke point in the system
it needs to maintain 5+ min or better 6+ PSI thru the traps
or not enough fuel, even if the jetting is right down low
might be a determining factor too
what kind of PSI is it ? (fuel), when 'the fall off' happens
(you really need to know that stuff)
or you're just shootin' ducks in the dark

proper size of fuel lines to & from the tank ?
anything smaller than a 3/8''s is asking for trouble

also a bypass style regulator & good electric 120+gpm pump
is sort of the std. equipment now
not that a mechanical pump can't do the job
as long as it's not some cheap low flow POS

good luck

edited;
even if that's not the issue it should all be addressed
or you will just be fighting, **** down the road
with a new cam, springs, carb, intake, ignition curve etc.

 

[malex]

I experienced a lay-over condition a few race days back. No more problem since I added jet extensions in the rear bowl. What made it show up so obvious was that I checked and made a minor adjustment to the rear float as it was on the high side. The car was going lean at high RPM. Maybe you are experiencing the same thing I went through.

 

[66Satellite47]

My 2 cents, fuel system (float level, jet size?, fuel pump ACTUAL delivery rate, too small fuel line), valve springs. I'd guess the EDE valve springs are marginal, but I'd sure test them. Fuel line size & pickup can really screw up a mechanical pump.

 

[kjalltrac]

Dont get me wrong here, but if it would go lean, it would show up on the afr meter, and it doesn't. It acts the same in any gear during the run.
(Can add that it free rewing in neutral to well over 6000rpm)

I used an orange mopar ignition box a couple of years back and acted the same as now, except it rolled over at around 4000rpm. Installed the msd 6a and it pulled hard to around 5000-5500rpm.

 

[PRHeads]

BTW, the motor from the dyno sheet I posted had valve springs from a set Edelbrock RPM heads, set up at 140-145lbs on the seat.
No signs of float to 6600.

That’s one of the main advantages of the solid lifters.......much better stability in the upper rpm.

Fast rate hyd cam, std hyd lifters, high rpm....... pick 2.

Do a search for “mild mannered mauler” from Mopar Muscle, from around 2005.
It’s a great example of what you’re likely experiencing.

Also, fwiw....... we used to dyno a few NASCAR Busch North series motors....... and we used the MSD 6A box during that testing.
We would pull them to 8500.

 

[Frank Mopar]

I got to think the 13/4” headers are a choke point.

 

[BSB67]

I got to think the 13/4” headers are a choke point.

At this power level they might be a tad small from perfect (he's only at about 400 HP) but by far from a choke point. I think 383man has gone 11.5s at 115 with 1 3/4" . Heck, my manifold 508 pulls to 6500.

 

[kjalltrac]

I've seen similar combos like mine putt down around 480-500hp usually around 5300-5800rpm
I don't think the exhaust/headers are the problem here.
I personally don't believe there is a fuel delivery problem either.
I have my mind set on the cam/lifters/springs.
Just curious if anyone else have any ideas that I might not thought of.
Thank you all for your inputs so far

 

[PRHeads]

Did the motor still feel lazy after 5000rpm with the 100 shot?

The 60’ times are weak for solid 11’s out of a fairly mild stock stroke 440.
3000 stall(assuming an 11”) is going to a hurdle.

Should consistently be in the very low 1.70’s to high 1.60’s.

Addressing the valvetrain stability will help the top end pull, but won’t do much(or anything) to the 60’ times.

It’s easier to have the 60’ times be soft and still run the ET when you have more power than necessary(mph) to reach the goal, but you’re not at that point....... so you should be looking at improvements at both ends of the track.

 

[66Satellite47]

Dont get me wrong here, but if it would go lean, it would show up on the afr meter, and it doesn't. It acts the same in any gear during the run.
(Can add that it free rewing in neutral to well over 6000rpm)

I used an orange mopar ignition box a couple of years back and acted the same as now, except it rolled over at around 4000rpm. Installed the msd 6a and it pulled hard to around 5000-5500rpm.

I have known of several "orange box" users that had similar issues. Mopar says orange box is good for 5500. My old Blue Box would go 7000+ easy, MSD 404BC went 8400(massive valve train damage!).

 

[kjalltrac]

Did the motor still feel lazy after 5000rpm with the 100 shot?

The 60’ times are weak for solid 11’s out of a fairly mild stock stroke 440.
3000 stall(assuming an 11”) is going to a hurdle.

Should consistently be in the very low 1.70’s to high 1.60’s.

Addressing the valvetrain stability will help the top end pull, but won’t do much(or anything) to the 60’ times.

It’s easier to have the 60’ times be soft and still run the ET when you have more power than necessary(mph) to reach the goal, but you’re not at that point....... so you should be looking at improvements at both ends of the track.

I agree, will probably swap the cam to a more agrassive solid cam and a 9,5" 3500-4000rpm torque converter for next season.
It acts pretty much the same on nitrous

 

[Frank Mopar]

I have known of several "orange box" users that had similar issues. Mopar says orange box is good for 5500. My old Blue Box would go 7000+ easy, MSD 404BC went 8400(massive valve train damage!).

Swap out the orange box for a HEI setup. Inexpensive plus you will have a much better ignition system. Use the separate coil and controller not the coil in the cap.

 

[PRHeads]

It acts pretty much the same on nitrous.

Really sounds like valvetrain issues.

Solid cam and a 9.5” converter should put you right in the 11’s.

 

[66Satellite47]

I missed the fact that OP has a MSD 6A. That box will go 7000+. Coil, carb going lean (but if A/F is good, not that), cam maybe. Seems small, especially if not a real "modern". My drag motors used a "bigger" cam. Base cam for my 440 size motors was 565 Int/585 Ex 265/270 @ .050. But that's an antique design. Newer use a bit less duration. Seems like lift should be closer to .590 with pocket ported aftermarket heads. My opinion. PHRHeads is correct solid, one less variable, top quality 9.5 converter would be the ticket.

 

[PRHeads]

I figure...... in 1990 I was running low 11’s @121-122 with the .510 lift Racer Brown ssh-44....... so in my mind the lift isn’t really the issue.
My heads flowed way way less than cleaned up Eddy’s too.

But the motor would easily pull 6500, and I had a pretty good 9” converter.

Motor dynoed at 535/535.

It’s really all about the combo being “right”.

Hyd lifters just seemed to be better back then too.

With the current crop of stuff out there these days, I figure a BB with a hyd flat tappet cam is a pretty safe bet up to about 5500rpm.
If you really want/need more than that.......avoid the hyd lifter blues and just run a solid.

 

[66Satellite47]

PRH, I sure agree. Bet your Racer Brown was a lot more "bad ***" than what he has. So was my early '70's General Kinetics 585/310 or Cam Dynamics 565/585, both solids. I still consider this as a 440 baseline, although not as good as modern profiles. Both of my old grinds would go 7000 RPM. My porting on the 906's really gave the added power. Not sure what EZ Streets are like, I had EDE RPM's. Even those needed cleanup & pushrod lump opening.

 

[PRHeads]

I had ported my 2.14/1.81 906’s with some guidance from the guy we had doing the head porting for the shop I was working at back then.
I went ahead and did what he suggested, and they were what they were.

A couple years later I bought my first flow bench (1992), and when the heads were off the motor I tested all the ports.
The 8 cylinder average for all my work was an earth shattering 239cfm.

E Streets are the exact same casting as the RPM.
So, way better than 239cfm.

It’s been a long time since I did it, but I plotted out that ssh-44 and my recollection is that it was 244 or [email protected], and about [email protected](the published spec is [email protected], but mine measured bigger than that).
That was a good cam.

 

[kjalltrac]

PRH, I sure agree. Bet your Racer Brown was a lot more "bad ***" than what he has. So was my early '70's General Kinetics 585/310 or Cam Dynamics 565/585, both solids. I still consider this as a 440 baseline, although not as good as modern profiles. Both of my old grinds would go 7000 RPM. My porting on the 906's really gave the added power. Not sure what EZ Streets are like, I had EDE RPM's. Even those needed cleanup & pushrod lump opening.

The e_streets are the same castings as the rpms

 

[66Satellite47]

The e_streets are the same castings as the rpms

Did not know that. They should be good past 7000 with the correct cam & intake. In the old days I used a TM 7 850 DP, with my 585/310 General Kinetics solid cam, 7000 RPM shift points. Tough on the steel crank, 300 runs @ 7000. 6500 will live much longer.

 

[kjalltrac]

Since I have a cast crank, ly rods and heavy pistons, I really don't feel comfortable rewing it past 6000rpm, but I want it to pull hard to my shifting point.
Any suggestions on a suitable solid cam, should probably be in the 0.55 to 0.6 lift range?
Maby this cam
https://www.lunatipower.com/voodoo-solid-flat-tappet-cam-chrysler-361-440-272-280.html