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1986 720 2.4 liter - Is there a simple carburetor swap?


jagman

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I have removed the head and the timing cover of the engine and am faced with putting the original carb and all the vacuum lines and equipment back or just replacing the carb with a simple two barrel with manual choke.  Has anyone done this?  What is required?  What carb did you use?  Anything to be aware of that would cause a significant problem?  Thanks Steve.

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if you dont live in a smog state go for 32/36 weber. only hose is fuel and dizzy tube. would suggest if not already electric pump and some say you dont need a regulator but I would install one so you know that the weber is getting its 3psi. EASY to tune idle speed and air/fuel and there are PLENTY of forums on it and countless manuals and guides to help.

Edited by Toxicrain
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I have ordered a redline conversion kit as you suggested.  In the two weeks it will take to get here I have to attempt to get the liquid nails off the timing cover mating surfaces.  When I pulled the head I found the head gasket put on incorrectly and covering some of the cooling passages also using what looks like liquid nails as a sealant.  It will be a job to get that s..t  off.

 

But I have another question ...  what is the single wire connector on the water pump for?  Thanks Steve

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Do you have a carburetor or throttle body EFI on your '86? Carburetor is a single butterfly nut holding the air filter on. If you have EFI a Weber will not work.

 

The Z24 head gasket indeed may have several holes in the block or the head that are covered and not used. If you get a Z24 gasket it will be proper. 

 

Perhaps misaligned? There are two alignment dowels on two of the head bolt holes on the driver's side of the block. They stick up about 1/4" and the head seats down over them. If one or both are missing the head can skew.

 

I would suggest having the head checked for flatness before assembling. If flat don't use any gasket dressings... obviously. 

 

The Z24 is problematic in blowing the gasket every 100K so once a year or every tune up re-torque the head bolts to assure adequate clamping on the compressed gasket. It very easy. On a COLD engine loosen only one bolt at a time and immediately torque to 60 ft lbs. Now move to the next. You can do in any order BUT only one bolt loose at a time.

 

The water pump normally doesn't have a wire to it. Maybe someone grounded something to it? Post a picture of it.

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I have a carb setup .. no efi.  So I am lucky in that regard.  The disassembly of the timing cover and the head has been a chisel and pry operation.  I want to behead the as.....e that last worked on it.  Now thinking that I will try acetone to take it off otherwise a file!  I don't have a camera that can give me digital media to upload  but the round single connector connection in question is positioned to the right of the square two contact temp sender.

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6 hours ago, captain720 said:

Why can't you put a Weber on a Z24 EFI setup? 

 

I think the manifold is much different from the carb manifold. Also the fuel pump is high 40 PSI pressure. The distributor is replaced with a crank angle sensor (CAS) run by the ECU which needs sensor inputs from the throttle body to set the spark advance. 

 

 

Is the distributor, water and oil pump removed??? These have to come off to get the timing cover off.

 

NEVER use sealant on a gasket. That's the gaskets job. This isn't the 1950s. Nissan didn't use it when assembling it.

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Where can I get a replacement 90 degree rubber hose that is going to the crankcase breather tube?  When I disassembled the head I found the one on the engine in two pieces.

The local parts stores "may" have the bypass hoses but don't have a clue about the breather hose.

Steve

 

PS:  I have a pointy head but the car appears to have a flat one thankfully.

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2 hours ago, captain720 said:

Just put a tiny cone filter on it, it will have the same affect as just plugging it into the bottom of the air filter. 

 

This is the PCV to engine vent tube. A cone filter is not going to cut it.

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Datzenmike is correct. This rubber 90 connects to the base of the intake manifold and that is where there is no room to put a straight hose without a preformed bend.  Where can I get oone of these?

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Oddly enough, I ran into a 40 year veteran of Advance Auto ( Now retired )  who suggested that I use a 5/8" x 90 elbow heater hose to make the connection and that it would most likely last my lifetime before needing a replacement.  At my age that's easy to understand!  I now have the repair manual so I can look for that odd electrical connection on the block near the water pump.  Love  you guys.. 

 

Just an aside:  I went to the largest nissan dealer in the area and asked for the 90 by part number.  They told me they can't do a parts lookup for a vehicle more than 10 years old.  Not particularly helpful regarding their older vehicles nor was the parts staff very friendly when they found out I was looking for old stuff.

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Did you quote the part number I posted? They will at least look it up and say no longer available. A good manager can sometimes get interested in your project and (maybe bored) can send out e-mail to all other dealers that may have that part sitting in their inventory. It is a bit of a long shot.

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15 hours ago, datzenmike said:

Did you quote the part number I posted? They will at least look it up and say no longer available. A good manager can sometimes get interested in your project and (maybe bored) can send out e-mail to all other dealers that may have that part sitting in their inventory. It is a bit of a long shot.

I have an amazing parts guy that always does this type of thing for me

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I got the book for the truck and have looked at the drawings and the illustrations trying to find that  single pole connector on the intake manifold next to a two pole connector to determine what it is.  No luck from the book.  It has to be some sort of switch that controls something?  Mine is broken and I can't even find a part number for it, let alone  what it's for.

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4 hours ago, jagman said:

I got the book for the truck and have looked at the drawings and the illustrations trying to find that  single pole connector on the intake manifold next to a two pole connector to determine what it is.  No luck from the book.  It has to be some sort of switch that controls something?  Mine is broken and I can't even find a part number for it, let alone  what it's for.

A picture of the part would help.

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I have located a replacement part for the 11828 90 degree tube to the pvc valve on the intake manifold.  Summit racing has a 5/8" 90 heater hose. Their number is DAC-70001 for $3.99 + shipping that fits easily with a 1" shortening on the pvc side.  My book doesn't show that connector on the intake manifold but I will take a look at the wiring schematic to see if I can locate a likely terminus and function.  Thus far I have reinstalled the timing chain and the head.  Today I hope to complete that job and start the install of the new carby and strip the engine compartment of all extraneous gizmos and gimcracks that are not needed.

Thanks for the input and help guys!

Steve

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Hello Datzenmike.  It is electrical.  A single wire  (Black)  and appears to be a temperature sensor of some kind. To the left of it is a two wire connector.  It is on the intake manifold just behind the water pump outlet. 

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yCkRSBf.jpg

 

Lower right is the temp gauge. The other was a temp sender for EFI. Later it was moved to the head near the #1 exhaust spark plug to be closer to,  and have a faster response to the real engine temp. This helped the EFI set the warm up mixtures and to know when the engine was warmed up. This is from an '81 S110 200sx Z20E I had, I think. It may have been used on the 720- with feedback carb or the throttle body injection intake.

 

The

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