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Re: 440 falls off at 5 grand...Stumped
[Re: dezduster]
#1471781
07/24/13 02:20 PM
07/24/13 02:20 PM
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Joined: Jan 2003
Posts: 15,323
Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,323
Omaha Ne
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Silly question, what is the RPM range of the cam??? 1. Fuel pressure, easily checked by installing a fuel pressure gauge and making a quick test run. If you're dropping below 6 psi you have to resolve the issue. 2. Try a run without the air cleaner, I got my backside kicked years ago by a big block that had to small of an air cleaner on it. Another similar situation was due to the air cleaner lid being too close to the top of the carb due to hood clearance. 3. Try un corking the motor. A restricted exhaust will drive you nuts. Think, mouse nest, collapsed baffle, heat riser stuck 1/2 shut etc. 4. Valve springs. I am not familiar with the 303 lunati but if it has steep ramps, springs, weak or not will cause the problem. IF that is the culprit it may also be prone to burping gas out of the carb due to the valves floating.(should be apparent with the hood and air cleaner off. One can make a series of test runs to establish the exact RPM that the problem occurs. Install .060 t.125 shims under the springs and repeat the test. IF the RPM moves up you have found the issue. 5. Along shot would be other valve train issues, IE: geometry, rocker arms/ interference, pushrod length etc. keep us posted 
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Re: 440 falls off at 5 grand...Stumped
[Re: stinger]
#1471783
07/24/13 02:38 PM
07/24/13 02:38 PM
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Joined: Nov 2003
Posts: 5,048
Atlanta Indiana
Dave Watt
master
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master
Joined: Nov 2003
Posts: 5,048
Atlanta Indiana
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Quote:
and hemi race springs what ever that means. they are single with dampners.
My buddy had those springs on his '68 Pure Stock Hemi, it fell on it's face at 5,300 RPM's, changed to a different spring, now it will go 6,000 no problem.
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Re: 440 falls off at 5 grand...Stumped
[Re: Dave Watt]
#1471784
07/24/13 04:50 PM
07/24/13 04:50 PM
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Joined: Jan 2003
Posts: 15,323
Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,323
Omaha Ne
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Quote:
The Lunati 303 is one of the larger of the Voodoo cams, which have quick ramps. That's why I say springs. The OP didn't build the heads himself so he doesn't know what they are.
Quick ramps require a stiff spring 
Quote:
Quote:
and hemi race springs what ever that means. they are single with dampners.
My buddy had those springs on his '68 Pure Stock Hemi, it fell on it's face at 5,300 RPM's, changed to a different spring, now it will go 6,000 no problem.
it would appear as though the springs may be the issue, some of the things I suggested earlier are fairly easy things to check and can definitely cause the problem described. if the two above quotes are factual then the springs are probably at fault.
 
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Re: 440 falls off at 5 grand...Stumped
[Re: stinger]
#1471786
07/27/13 08:44 PM
07/27/13 08:44 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Alright it ain't fuel starvation. EDIT got a points or electronic dizzy/system that you can sub in for a test? I feel lucky
Last edited by RapidRobert; 07/27/13 08:46 PM.
live every 24 hour block of time like it's your last day on earth
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Re: 440 falls off at 5 grand...Stumped
[Re: Sinitro]
#1471787
07/28/13 05:16 AM
07/28/13 05:16 AM
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Joined: Jan 2003
Posts: 12,043
State of Confusion
hp383
Just a normal tag again
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Just a normal tag again
Joined: Jan 2003
Posts: 12,043
State of Confusion
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Quote:
Obviously you have hydraulic lifters..
If original Mopar OE stockers 5K or a little over is all you will get...
Just my $0.02... 
My 383 had a 292/509 old school purple shaft with stock springs and rockers, and Summit hyd lifters. It would pull hard up to 7200 and would keep going if I didn't shift or back off.
Previous owner used it for bracket racing and would hold it to 8000 on the shifts.
When I first installed the engine it would fall flat at about 4800-5000, mine ended up being a bad carburetor. I switched from the Holley it came with to a new Eddy 750 and wow, that woke it up.
Latter added the tunnel ram and a second Eddy 750 and I couldn't stop giggling.
But it seems the OP had determined its not a fuel issue.
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Re: 440 falls off at 5 grand...Stumped
[Re: 52savoy]
#1471789
07/28/13 07:52 AM
07/28/13 07:52 AM
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Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan
I Live Here
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I Live Here
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Posts: 10,847
Oakdale CT
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Quote:
The usual.. mopar valve spring bashing  
And mine (springs recommend by MP) had lost 50% of its rated pressure in a week as did the next set. I wasted hundreds of dollars chasing the problem not to mention track time and more $$$ towing too and fro.
Good luck with your springs, russian roulette if you ask me.
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Re: 440 falls off at 5 grand...Stumped
[Re: gdonovan]
#1471790
07/28/13 12:30 PM
07/28/13 12:30 PM
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Joined: Dec 2005
Posts: 4,231
State of retirement
52savoy
master
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master
Joined: Dec 2005
Posts: 4,231
State of retirement
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I can't vouch for what's sold now. My springs have proven themselves by lasting all these years on nothing less than .600 lift. What else can I say other than I'll run them as long as the pressures stay up. 1970s and counting  As far a motor not revving...I agree with you guys. It can be gas delivery(pressure or adjustments), timing, valvetrain and possibly internal engine. I'm a big fan of common sense..I would never jump to the conclusion it's springs before eliminating other potential problems first 
Last edited by 52savoy; 07/28/13 12:36 PM.
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Re: 440 falls off at 5 grand...Stumped
[Re: 52savoy]
#1471791
07/28/13 01:33 PM
07/28/13 01:33 PM
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Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan
I Live Here
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I Live Here
Joined: Jun 2008
Posts: 10,847
Oakdale CT
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Quote:
I'm a big fan of common sense..I would never jump to the conclusion it's springs before eliminating other potential problems first
Which I already pointed out, taping a fuel pressure gauge to the windshield and going for a ride would eliminate the fuel pump as a possible issue.
Cheap stuff first.
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Re: 440 falls off at 5 grand...Stumped
[Re: stinger]
#1471792
07/28/13 02:15 PM
07/28/13 02:15 PM
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Joined: Jan 2003
Posts: 18,409
UPPER MICHIGAN, MARQUETTE COUN...
NITROUSN
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I Live Here
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Posts: 18,409
UPPER MICHIGAN, MARQUETTE COUN...
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Quote:
I picked up a summit dualfeed line with filter and gauge and a separate line to tape the gauge to the windshield. I got a constant 4 psi with no drop in pressure,engine still falls at 5 grand. I took theline off and installed it to the feed line and get a chatty 6.5 psi. I also replaced the fuel pump rod with a mancini one.
I would verify the needle and seat are correct. There is a certain size needed to allow enough fuel to enter the bowls. If to small you may be starving for fuel even though you have pressure. Pressure is flow to resistance.
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Re: 440 falls off at 5 grand...Stumped
[Re: stinger]
#1471793
07/28/13 02:51 PM
07/28/13 02:51 PM
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Joined: Jan 2003
Posts: 15,323
Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,323
Omaha Ne
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Quote:
I picked up a summit dualfeed line with filter and gauge and a separate line to tape the gauge to the windshield. I got a constant 4 psi with no drop in pressure,engine still falls at 5 grand. I took theline off and installed it to the feed line and get a chatty 6.5 psi. I also replaced the fuel pump rod with a mancini one.
Ok, Lets assume fuel pressure is OK.
Does it drop at the same RPM in a 3 gears???
1. try the air cleaner off, (been bit twice by that, and its a kwik test,
2. if your running Chrysler electronic ignition you can try another control box, (long shot but again cheap and kwik)
3. next, I would try uncorking it,
4. valve spring time
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Re: 440 falls off at 5 grand...Stumped
[Re: NITROUSN]
#1471794
07/28/13 10:34 PM
07/28/13 10:34 PM
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Joined: Jul 2007
Posts: 461
Detroit Michigan
stinger
OP
mopar
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OP
mopar
Joined: Jul 2007
Posts: 461
Detroit Michigan
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Quote:
Quote:
I picked up a summit dualfeed line with filter and gauge and a separate line to tape the gauge to the windshield. I got a constant 4 psi with no drop in pressure,engine still falls at 5 grand. I took theline off and installed it to the feed line and get a chatty 6.5 psi. I also replaced the fuel pump rod with a mancini one.
I would verify the needle and seat are correct. There is a certain size needed to allow enough fuel to enter the bowls. If to small you may be starving for fuel even though you have pressure. Pressure is flow to resistance.
I've thought of this but not checked into it yet.bought a used carb and rebuilt it with a fast kit. I still think it's a fuel issue,car dose not sputter or pop,just sounds like running out of fuel. cant find info on what size needle seats are used.???
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