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  #1  
Old 03-17-2009, 08:55 PM
74sunburst 74sunburst is offline
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Default Re: 440 no power.

Hey guy's this ones for a friend of mine....He has a 72 Roadrunner 440 with 727 trans. The car runs/drives fine but it will not accelerate hard at all it just pops very quietly it sounds sort of like a exhaust break.I'm thinking its a weak valve spring letting a valve open a little?Or could it be that the balancer has spun? The motor was rebuilt awhile back and ran fine. Since the problem started most parts have been replaced ie:New Mopar performance distributor kit,New Holley carb,Taylor 8mm wires,plugs,hot coil,New fuel pump/tank/lines/filter. I don't see much left to check.
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  #2  
Old 03-18-2009, 05:44 AM
buckneccid buckneccid is offline
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If you think it's a valve problem, hook a vacuum gage to a manifold vacuum source. The gage should hold steady.If it bounces or fluctuates, then there's a good chance that's where your problem lays. If you have that, move on to a compression gage, check each cylinder, and the one low cylinder should be your bad valve. If all read low or the readings are all over the place (more than about a 10% difference between the lowest and highest) then you have something along the lines of bad rings or blown head gaskets. This is oversimplified, but it should give you some good info to go on.

This sounds like the problem hasn't changed much since before the distributer change, have ANY of the changes made a difference?
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  #3  
Old 03-18-2009, 09:14 PM
74sunburst 74sunburst is offline
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Ok we checked the Compression tonight the #'s seem low:
#1. 90
#2. 90
#3. 90
#4. 108
#5. 90
#6. 159
#7. 90
#8. 100
We did this twice and got the same #'s both times.The car does not seem to burn oil,it does have some valve train tick(very quiet).I will try adding some oil into the cylinders and doing it all again after work.Is there any thing else I can try or look at?
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Old 03-19-2009, 02:08 AM
Cudafever Cudafever is offline
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That # 6, i would check one more time before you add oil.......if it is for sure that hight and the rest are that low..............and oil bring then up close to that #6 compression.............Well it time for a eng rebuild.

Here's another avenue to look at....... could the popping noise be, because your timing chain is completely wore out.....

Bring the eng up to t.d.c. on you harmonic balancer, remove you dist cap. Now turn your crank in the opposite direction as before, WHILE LOOKING AT THE IGN ROTOR. When the rotor starts to move, STOP and look at you harmonic balancer again. Did it move more then 10 or 12 degrees? if so the popping may be a chain thats wore out and cause the popping noises coming up thru the carb.

Run some oil in the cylinder before you move on to this.......Just some extra thoughts.
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  #5  
Old 03-19-2009, 04:40 AM
DartGT66 DartGT66 is offline
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Perform a leak down test, or have it performed. Check the valvelifts in different cylinders to find out if the cam is ok. And check the cam timing at #1 cylinder at TDC, you should have the #6 cylinders intake and exhaust valves about equal amount open with the #1 at TDC. Those are relatively easy checks and should give you a lot of info. The compression test alone is pretty much worthless, but the big differences tells that you definitely have got a problem. I think it's valve involved.
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  #6  
Old 03-19-2009, 04:03 PM
74sunburst 74sunburst is offline
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Ok guy's I'll get on it tonight and I'll get back with some more info.Thank's
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  #7  
Old 03-19-2009, 04:31 PM
74sunburst 74sunburst is offline
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Any chance the Crank pully could have spun on it self? Would that cause this problem?
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  #8  
Old 03-22-2009, 11:28 AM
74sunburst 74sunburst is offline
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Ok we checked every thing all out, the motor is punched.We are going to yank it out today for a rebuild.Thank for your help
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  #9  
Old 03-22-2009, 01:53 PM
Cudafever Cudafever is offline
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Take your time disassembling it............it could tell you some valuable info to help you build a better one in the end
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  #10  
Old 08-14-2010, 09:31 PM
74sunburst 74sunburst is offline
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It was a badly worn cam, I don't know how it ran so well. It's all rebuilt now and running perfect Thank's for all the help.
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  #11  
Old 08-15-2010, 04:46 PM
Cudadrag Cudadrag is offline
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Damn. Didn't see this post in time. Sounds identical to my motor meltdown. Some of the cam lobes worn bad. Strange how when they go south it happens fast. I did the heads first then called Comp to custom grind me a cam to my motor size/compression and valve size/spring strength for about the same price. I was surprised they recommended a slightly lower lift and longer diration profile than the Mopar purple grind cam I ground down. Should be firing up shortly.
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  #12  
Old 08-15-2010, 07:29 PM
RacerHog RacerHog is offline
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Glad to here your happy with it.....
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