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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: sixpack4spd]
#1343244
11/30/12 09:59 PM
11/30/12 09:59 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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My turn... I doubt it's the valve spring pressure. I run 105 seat pressure and around 350lbs open on a Lunati .600 solid lifter cam. I've ran those springs for 35 years and will continue to unless something changes drastically. Did you check/cut the valve guides so the retainer doesn't bottom out at max lift? Block decked any? Check pushrod scrub pattern? If all that is good, I would agree with some of the others...ignition and or timing.   This might be pushing it a little.. but did you mash the pedal down all the way and check the carb? 
Last edited by 52savoy; 11/30/12 10:44 PM.
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: 52savoy]
#1343245
11/30/12 11:47 PM
11/30/12 11:47 PM
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Joined: Apr 2003
Posts: 12,234
Looking for a way out of Middl...
IMGTX
I Live Here
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I Live Here
Joined: Apr 2003
Posts: 12,234
Looking for a way out of Middl...
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Quote:
This might be pushing it a little.. but did you mash the pedal down all the way and check the carb?
I was thinking the same thing.
I had a car wouldn't get up into the RPM's and it was because the linkage on the carb would bind and not open fully. If the primaries do not open fully it will usually prevent the secondaries from opening at all. If it's vacuum secondary make sure the diaphragm is OK.
2nd thing to do is replace the points & Condenser. As said already, a bad condenser can cause weird problems but a weak points spring can cause the points to float at speed effectively preventing spark and becoming a rev limiter.
While your in the distributor compare the distributor cam to a known good one and make sure the distributor lobes aren't worn down. If you don't have a known good one post pics. Somebody on here will let you know. Don't forget to grease the point's rub block and distributor cam lobe.
I also had a dual point distributor that wouldn't run higher RPM's if one set of pints was disconnected.
If the Carb is opening all the way and the distributor is OK then check the cam timing. IMHO.
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: MrBelvedere2]
#1343247
12/01/12 12:48 PM
12/01/12 12:48 PM
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Joined: Jan 2003
Posts: 644
Warner Robins, Georgia
DusterMan
super street
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super street
Joined: Jan 2003
Posts: 644
Warner Robins, Georgia
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Does your tach have a rev limiter on it? I had a friend that messed with his car for a few days would not rev over 2500. Someone turn the dial down. A thought.
Pete:
2003 Dodge Quad 2500 Hemi
69 RoadRunner 4 sp Alpine White
2019 Dodge Charger
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: Dodgem]
#1343249
12/01/12 03:39 PM
12/01/12 03:39 PM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
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Single point distributor? What is your dwell? When reving the car in neutral past 4000rpm, what does the dwell change to? Is it going to zero?
Can you see any unusual pitting on the contact surfaces of the points? Are you using Accel or Blue Streak points?
Last edited by jbc426; 12/02/12 03:17 PM.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: HYPER8oSoNic]
#1343251
12/01/12 10:44 PM
12/01/12 10:44 PM
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Joined: Dec 2007
Posts: 1,584
MD
p d'ro
pro stock
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pro stock
Joined: Dec 2007
Posts: 1,584
MD
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I agree that it may be something simple like the linkage. Mine just had the throttle cable come loose and it wouldn't pull. Check that when gas pedal is down that linkage is wide opened.
Last edited by p d'ro; 12/01/12 11:03 PM.
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: p d'ro]
#1343252
12/02/12 03:04 PM
12/02/12 03:04 PM
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Joined: Dec 2003
Posts: 306
Texas
bogusracer
enthusiast
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enthusiast
Joined: Dec 2003
Posts: 306
Texas
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As suggested before, check your carb for wide open with someone else mashing the pedal to the floor. If that's ok, check your fuel delivery system. Sounds like its running out of fuel. Could be as easy as a fuel gauge not reading correctly and not enough fuel in the gas tank (that happened to me at the Drag strip once). If you have enough gas in the tank, then check the fuel delivery system. Fuel pump pressure and delivery rate, possible clogged fuel filter, check to see if the pickup in the fuel tank has a sock filter that is collapsed or clogged up. Make sure you don't have too much rubber fuel line on the suction side of the fuel pump which might collapse as the pump suction increases as the rpm increases. Just a few suggestions here as you did not say there were any popping issues etc. in your initial statement concerning the problem. If it just noses over and doesn't pull and it did before, that's where I'd look. Good Luck. Bogusracer
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: stumpy]
#1343254
12/05/12 02:23 AM
12/05/12 02:23 AM
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Joined: Feb 2007
Posts: 649
Davis, California, USA
MrBelvedere2
OP
mopar
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OP
mopar
Joined: Feb 2007
Posts: 649
Davis, California, USA
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Hey guys, thanks for all the advice so far. I was able to work on the car tonight. I got my 750cfm holley double pumper, built by a pro for my engine. I also have firecore spark plug wires that are brand new, also new autolite 85 plugs gapped correctly. I also swapped my points distributor for a known-good pertronix distributor set up with a performance curve. I fired the car up,and it still will no go over 4,000 rpm. I would hate to think its the heads. This motor is pretty much brand new and has about 1500 miles on it.unfortunetly the place that built it is out of business. You rev it up and it sounds like it's running somewhere, just seems to hit a stop at 4,000 rpm. I did put new pushrods in it, they are the stock length. I do know the motor was decked enough to remove the stampings on the distributor pad. Would that be enough to warrant custom length pushrods? I was told when I purchased the motor to use stock length pusrods. I am running a hudraulic cam with stock stamped rockers. I'm running out of ideas.
1965 Plymouth Belvedere II hardtop
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: MrBelvedere2]
#1343255
12/05/12 02:58 AM
12/05/12 02:58 AM
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Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
Striving for excellence
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Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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Quote:
Hey guys, thanks for all the advice so far. I was able to work on the car tonight.
That explains your absence at tonights car club meeting... 
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: MrBelvedere2]
#1343258
12/05/12 04:53 AM
12/05/12 04:53 AM
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Joined: Jan 2003
Posts: 27,468
So Cal
autoxcuda
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,468
So Cal
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Quote:
Hey guys, thanks for all the advice so far. I was able to work on the car tonight. I got my 750cfm holley double pumper, built by a pro for my engine. I also have firecore spark plug wires that are brand new, also new autolite 85 plugs gapped correctly. I also swapped my points distributor for a known-good pertronix distributor set up with a performance curve. I fired the car up,and it still will no go over 4,000 rpm. I would hate to think its the heads. This motor is pretty much brand new and has about 1500 miles on it.unfortunetly the place that built it is out of business. You rev it up and it sounds like it's running somewhere, just seems to hit a stop at 4,000 rpm. I did put new pushrods in it, they are the stock length. I do know the motor was decked enough to remove the stampings on the distributor pad. Would that be enough to warrant custom length pushrods? I was told when I purchased the motor to use stock length pusrods. I am running a hudraulic cam with stock stamped rockers. I'm running out of ideas.
Seems like you are going through the elimination process. Before I pulled the heads, I pull off the water pump housing, timing cover and check the timing chain marks.
Could be heads too. Pick your poison. I think checking the timing marks would be less costly in terms of parts.
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: Dodgem]
#1343260
12/06/12 10:48 PM
12/06/12 10:48 PM
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Joined: Feb 2007
Posts: 649
Davis, California, USA
MrBelvedere2
OP
mopar
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OP
mopar
Joined: Feb 2007
Posts: 649
Davis, California, USA
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I would love to try those shims for the rockers, but the problem is this motor is an early big block with the 4-bolt max wedge style heads, and has the bolt-on rocker shaft post, not the casted-in style. Maybe I can just make some .040 shims from square stock and try it that way?
1965 Plymouth Belvedere II hardtop
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: MrBelvedere2]
#1343262
12/07/12 11:00 AM
12/07/12 11:00 AM
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Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem
master
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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Quote:
I would love to try those shims for the rockers, but the problem is this motor is an early big block with the 4-bolt max wedge style heads, and has the bolt-on rocker shaft post, not the casted-in style. Maybe I can just make some .040 shims from square stock and try it that way?
Yea just shim the post up. .04 then .06
pop cans can be cut square and drilled for low buck shims thin so you have to stack some together!
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Re: Motor won't rev over 4,000 rpm. Valve springs?
[Re: Dodgem]
#1343263
12/07/12 06:28 PM
12/07/12 06:28 PM
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Joined: Jan 2003
Posts: 3,050
Bowling Green, KY
cudaboy
master
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master
Joined: Jan 2003
Posts: 3,050
Bowling Green, KY
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Quote:
however, I had a mishap once... mis-read the timing marks on the gears when I installed them. cam ended up about 30 degrees advanced. engine fired right up and ran great. but it would NOT rev over 3,000 rpm.
I did the same thing. It ran great, but at 3000, it just stopped.
Dennis
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