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1985 720 4X4 No Power


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#1 SRB87

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Posted 03 January 2017 - 05:10 PM

Just bought my 85 Nissan 720 Z24 4X4. I checked the timing its at 10 degrees, the firing order is correct, no vacuum leaks. Both coils are sparking. Truck runs, idles, drives but has no low end power. any help would be nice thanks



#2 Charlie69

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Posted 03 January 2017 - 09:56 PM

A plugged catalityc converter will cause this. 


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#3 Lockleaf

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Posted 03 January 2017 - 09:59 PM

Low compression, head gasket or otherwise could cause it, if the compression is low but equal across the cylinders.

Also, timing should be 3 or 4 degrees on a stock motor.

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#4 datzenmike

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Posted 04 January 2017 - 06:13 AM

I was leaving the blown head gasket for last. If blown between cylinders this would cut performance. Best to eliminate the obvious and easily fixable first.


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#5 RasselFlassel13

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Posted 06 January 2017 - 02:31 PM

Same thing happen to mi with the second one I brought. Had a chip outta the piston near the edge on the ringland. With no compression in dat cylinder

1984 Datsun 720 2wd Z24 dirft truck 1986 Nissan 720 4x4 Z24 daily(broken piston)


#6 SRB87

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Posted 07 January 2017 - 07:47 PM

So up date, no Cat on truck. Adjusted valves, the spark plugs looked carbon up on cylinder 4 and a little bit on 3. 1 and 2 were wet with fuel. Need to check compression again after I adjusted the valves. Replaced spark plugs also. Does the vacuum have to 3-4 degrees with the vacuum advance unplugged or not? Thanks

#7 datzenmike

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Posted 07 January 2017 - 08:35 PM

There shouldn't be any vacuum at idle BUT... just to be sure you can pull the hose off the distributor.


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#8 SRB87

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Posted 08 January 2017 - 10:08 AM

Got the truck back together checked the timing when i put it down to 3-4 degrees it runs like crap, if i put it up to 25 degrees it works alright, not the best but has a little more power from where i started. When i hit the gas now it bogs down slightly.



#9 datzenmike

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Posted 08 January 2017 - 12:43 PM

Well something is off then. The timing V or the timing scale. Maybe the cam is timed wrong as well. I don't see how it could possibly idle at 25.

 

You must be inadvertently doing something wrong.


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#10 SRB87

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Posted 08 January 2017 - 05:28 PM

This is how i got the truck. I am just trying to figure it out. I ordered head gasket set and just going to replace it and start from scratch. might as well do it correct so it lasts a long time.



#11 datzenmike

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Posted 08 January 2017 - 06:31 PM

I'm saying what you describe is virtually impossible. I believe you it's just there has to be a mistake in how you are doing it.

 

 

Can you confirm that the plug wires are going to the correct plugs. There are 8 and it's easy to mix up. The order is 1342 and there are intake and exhaust sides.


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#12 SRB87

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Posted 10 January 2017 - 07:48 AM

Update truck runs great now. The head gasket between 2 and 3 were blown out. After I replace it. Put the timing to the correct degrees. Changed oil and filter also the coolant. Now it's time to get a new header do to manifold being warped. Also have to turn up the torsion bars tonight.

#13 Lockleaf

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Posted 10 January 2017 - 10:08 AM

$25 will get your manifold machined flat at a machine shop. You'll find most of us don't believe headers are worth anything on these trucks. The head itself is more restrictive than the exhaust.

Nice job getting it running.

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