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Alan2fast

240z low power cuts out

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Ok guys still new here as you guys probably seen just got my 73 240z running but when i give it gas to fast it wants to choke out and almost die and back fires out of the front carburetor. Carburetor were just fully built. Since the frist start i let it run for 15min in idle then reved the motor up and did fine so i took it for a drive and it was hard to get power unless i slowly give it gas then its good after and when i turn the car off the motor shakes hard feels like it wonts to stay on still

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After rebuilding the carbs you'll have to fine tune the adjustments.  Here's a helpful write up from member Blue, if they are SUs.

http://www.classiczcars.com/topic/39221-quick-and-dirty-su-tuning/

 

Hope that'll help. 

 

You'll have to upload the video to youtube then link it here.

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blue's info is excellent.

 

if you're running su's, it is a fairly straightforward process.

be sure you have adequate fuel supply to the carbs (pump, filters) then number 1 above all is float levels - get 'em right, or you'll chase your tail w/the other adjustments.

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Make sure you have oil in vacuum piston dampers. There is an endless debate on what oil to use but 10W30 is a good place to start.

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Thanks guys blues info lookes good ill get right to it and as far as the damper oil 10w30 what type of oil are we talking im runing 3in1

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I've only used the blue label 3in1 myself.  When everything else is working right I'm going to try different oils.  Here's my short list, ATF, John Deere hydrostatic 20 weight, 10w30.  I need to read more into it though as far what thickness works best for the weather around here.  The 3in1 is working good so far but I don't know what to compare it to. 

 

If you're going to keep your carbs I'd spend $30 on one of these, ebay or amazon has good prices.  Takes the guessing out of the process.  :)

 

post-7641-14150819739346.jpg

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Have you checked the timing? The popping or dieseling when cutting it off could be timing related...

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Ok guys still new here as you guys probably seen just got my 73 240z running but when i give it gas to fast it wants to choke out and almost die and back fires out of the front carburetor. Carburetor were just fully built. Since the frist start i let it run for 15min in idle then reved the motor up and did fine so i took it for a drive and it was hard to get power unless i slowly give it gas then its good after and when i turn the car off the motor shakes hard feels like it wonts to stay on still

 

If it spits both out of the carburetor AND backfire, things that come to my mind are timing and valve clearance

Did you do anything to the motor, rebuild it or what ?

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Yes i did replace a valve spring that was broke as you can see in the picture and had to readjust the valves maybe need to go back in and readjust again know that its running what should the proper adjustment be

39bd7c9fd6b7ba5bff19da5ad7a6c942.jpg

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The 3-in-1 SAE 20 works ok but I found that it disappears rather quickly and requires frequent topping off. Engine oil seems to last longer. As for viscosity, I found ATF to be a bit thin and finally settled on SAE 30, which is what I use in the engine.

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My timing marks are they good? also readjusted the valve clearnce but still the same

4f72037c2f0842f84f1a743e1cbecb63.jpg069b19a405aaf4eb6afa37d9ef3700fc.jpg46bf5426c19b4bb0e6e85ebbaee2926e.jpg

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Does not look quite right to me. Leave crank where its at and pull the distributor.

Check this for proper alignment phasing.

post-4108-0-09045300-1441932609_thumb.jp

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Ok ill try to get to that tomorrow or the weekend could be the problem if it off how hard is it to correct this

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Does not look quite right to me. Leave crank where its at and pull the distributor.

Check this for proper alignment phasing.

You were right its off so what do i do to correct this i hope easy

2549e288c50f5fa1ae1922f8ee3fc2c0.jpg

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Drop the oil pump and re-clock the spindle.

Ok so that sounds very easy but is it that easy unbolt lower down and turn to the correct postion?

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Sometimes the sway bar is in the way and has to be lowered. It is easier with two people. when you lower the oil pump, oil is gonna want to drip every where. You will need a catch pan. The spindle rotates as it disengages, so you have to lower it to disengage and rotate it some then push it up to reengage, until it is in the correct position like Lumens posted in #19. Once it is clocked correctly reinstall the oil pump bolts. The you will have to reset the ignition timing.

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