1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

high rpm engine problem

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Old May 10, 2007 | 12:07 AM
  #26  
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^^^^^use the softest spring for your vaccum secondary setup.
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Old May 10, 2007 | 01:48 AM
  #27  
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From: harrison, ar
Originally Posted by 85rotarypower
Sounds like a similar problem to mine mabey. Hits 5000rpm then kinda just dies and shutters a lot. Difference is I have an edelbrock with mechanical secondaries.
well, she don't die she keeps going but gets rough; a lot of vibration. ps, sorry about the bad spelling my girlfrend and i have ben taking turns at typing and we have been drinking tonight, but don't worry i would not drive drunk ok or work on the car drunk.
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Old May 10, 2007 | 09:21 AM
  #28  
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What has you convinced that the carb is behind this? Is it possible that the exhaust system is contacting the frame?
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Old May 10, 2007 | 10:02 AM
  #29  
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From: harrison, ar
Originally Posted by Kentetsu
What has you convinced that the carb is behind this? Is it possible that the exhaust system is contacting the frame?
exhaust system contacting the frame? why would this matter?
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Old May 10, 2007 | 10:59 AM
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Does it vibrate when you just rev it rather than drive it. Was the engine rebuilt??
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Old May 10, 2007 | 03:49 PM
  #31  
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both, and it has not been rebuilt, and it will do it when you rev up high just sitting in the driveway or when driving.
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Old May 10, 2007 | 03:53 PM
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How do the spark plug insulators look? What color?
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Old May 10, 2007 | 04:00 PM
  #33  
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From: harrison, ar
insulators? do you mean the porcalin?
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Old May 10, 2007 | 04:01 PM
  #34  
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bad spelling, sorry
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Old May 10, 2007 | 05:21 PM
  #35  
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From: so cal
So is it vibrating or making noises?
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Old May 10, 2007 | 05:27 PM
  #36  
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From: harrison, ar
mainly vibrating, but it doesn't sound very good past 5k
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Old May 10, 2007 | 05:27 PM
  #37  
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Where's the rotary hotline for some dialing and smiling.
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Old May 10, 2007 | 05:29 PM
  #38  
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Originally Posted by wackyracer
Where's the rotary hotline for some dialing and smiling.
huuu
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Old May 10, 2007 | 06:37 PM
  #39  
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From: harrison, ar
bump
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Old May 10, 2007 | 11:34 PM
  #40  
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Sounds like engine trouble to me??
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Old May 11, 2007 | 01:30 AM
  #41  
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From: harrison, ar
what kind of engine trouble?
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Old May 11, 2007 | 02:02 AM
  #42  
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If the exhaust system is in contact with the chassis at any point (metal to metal), then you will have a lot of vibration. The exhaust is supposed to be isolated from the chassis through rubber hangers to avoid these vibration issues.

The last time I heard of symptoms like yours, I suggested this and the owner found that the exhaust pipe had been welded to the tranny... Weird, I know. But if it touches metal to metal anywhere but the engine (which is itself isolated from the frame), well, then you'll feel it. I went through this with a 280zx, which is how I found all this out. Good luck...
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Old May 11, 2007 | 09:54 AM
  #43  
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From: harrison, ar
ok thanks, i'll look but im pretty sure it's not, i think it's hung properly.
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Old May 11, 2007 | 10:02 AM
  #44  
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From: calgary
So you exhaust is .......gotta say it ........."well hung" you say...
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Old May 11, 2007 | 10:05 AM
  #45  
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i knew that was coming, lol
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Old May 11, 2007 | 01:40 PM
  #46  
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How do the sparkplugs look?
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Old May 11, 2007 | 02:01 PM
  #47  
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Don't overlook ignition system problems. Higher engine rpms demand strong and accurate spark. Are you using the stock coils?...could they have been wired backwards?....the coils will fire if wired backwards but you will run out of spark at higher rpms due to running on the smaller primary winding in the coils. Make sure the polarity is correct. Often if you have fuel starvation the power drops off sharply but smoothly and not as much vibration and breaking up like your symptoms indicate. If you had a lack of spark advance, same result....smooth but no power. An ignition scope would help a great deal so you could look at coil output and polarity, plug wire resistance, etc. If you have a ohmmeter, check your plug wires. No more than about 10,000 ohms per foot.
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Old May 11, 2007 | 08:19 PM
  #48  
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From: harrison, ar
msd blaster 2's.
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Old May 11, 2007 | 08:25 PM
  #49  
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What fuel pump? You may be running out of flow. The stock pump is garbage.
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Old May 11, 2007 | 08:28 PM
  #50  
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From: harrison, ar
carter fuel pump.
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