'77 Datsun 280Z Carb FLOODING - Hot Rod Forum : Hotrodders Bulletin Board
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Old 03-04-2012, 02:08 PM
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'77 Datsun 280Z Carb FLOODING

So I have a problem to where the Carb is flooding out my engine. Can't get it to idle to adjust it so I'm kind of stuck. This is my first carbureted vehicle. I'm only 20 so I haven't been working on cars for long. I know my basics and a little more but I'm in the dark when it comes to carburetors. I can drive the car as long as I'm giving it gas but when I press in the clutch to change gears the engine whines up to about 6K rpms and then comes back down to where I have to keep pressing the gas to keep it running. Please help me out. Thanks in advance. It's a Holley four barrel carb but I'm not sure which series.
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Old 03-04-2012, 02:17 PM
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Sounds like you may have a few problems going on from a clogged carb and a vacuum leak. Clean and rebuild your carb and make sure the intake is fully sealed. Doing that will probably fix your problem AND give you much better mileage and performance.
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Old 03-04-2012, 02:51 PM
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Like I said I have no clue about carbs. So rebuilding it is gonna be a problem for me
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Old 03-04-2012, 02:53 PM
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Now the intake manifold is leaking gas from the bottom. i Just put a new gasket on it.
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Old 03-04-2012, 04:33 PM
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Since 77 datsun 280's came with efi, someone put that carb on (most likely a holley 390 cfm).


Need to check fuel pressure and make sure the carb linkage is working smoothly (since the linakge isn't stock anymore).
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Old 03-04-2012, 05:00 PM
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I still have the fuel injection stuff just A: don't know how to intall and get running properly and Bon't have the money to have someone do it. THe problem with the manifold seems to be that it only has bolts on the top to hold it to the block. So how is the bottom of the intake manifold supposed to seal?
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Old 03-04-2012, 07:14 PM
How fast is fast enough?
 
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Actually your problem is that old cars take time, talent, or money. You don't have any money (the case for many of us) and you don't know enough to have any talent. So this is going to take a lot of time on your part either swapping on the efi stuff (best option) and tuning it (the jetronic is a pita to tune) or rebuilding a carb and tuning that.

Either way there is no easy way out.

Btw the lower part of the intake is held on with the same bolts that hold the exhaust on, also you'll need rtv on the gasket. I have a 280 that I have done some work to so btdt.

Since you're just getting started the rebuilding a carb and properly installing the intake wil probably take 2 weekends, it'll take someone that's done it a few times a Saturday. You can pay someone else to do it but you're probably looking at $500+ at a garage.
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Old 03-04-2012, 08:59 PM
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Thanks. I really appreciate your help. The exhaust manifold doesn't seem to overlap the intake at all to hold it on. Do I have the wrong exhaust headers? It doesn't look like they've been changed (due to the discoloration matching the rest of the exhaust pipe.). I'm used to working on newer cars. I use to do a lot of ricer car work (honda, mitsubishi eclipse, and others). Now granted the datsun is considered a ricer because of it's nissan maker it's just an older ricer I'm dedicated to get this car in amazing shape and running condition. So I'm gonna spend hours researching how to do these things myself instead of having to pay someone else to do it. Thank you all for your help and I sincerely appreciate it.
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Old 03-05-2012, 08:13 AM
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shoot some pictures for us!
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Old 03-05-2012, 01:45 PM
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I'll get some up here today.
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Old 03-05-2012, 07:43 PM
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280z issue

Hey,

I have a 76 280z with the Arizona Z Car intake and holley 390 setup.

To answer your question about securing the bottom bottom of the intake manifold;

The bolts through the exhaust manifold should have a thick washer that overlaps the bottom of the intake manifold and is tightened down. There are not any bolt holes on the bottom of the intake manifold.

Also, as others have suggested, your overflowing is likely due to the fuel pressure being set too high.

Which pump are you using?
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Old 03-06-2012, 04:57 AM
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you can use the stock efi pump as long as you use the correct fuel pressure regulator. Actually I recommend using the stock efi pump as they are quiet and durable. Aeromotive makes a nice "return style" fuel pressure regulator that cab lower the pressure down to 5 psi. The key is to use a return style fuel pressure regulator when using a efi pump with a carb.


FYI, when using the stock efi pump and if you put in a tee at the front of the car and just loop the fuel back to the tank, there will be about 0.5 psi of fuel pressure at the tee.
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Old 03-06-2012, 06:28 AM
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You can fix the carb but I HIGHLY recomend swapping back to EFI. The stock intake is a bit of a restriction above 5000 RPM or so BUT if you plan on driving this on the street an EFI setup with megasquirt is MUCH better, you can literally just jump in, turn the key and go, regardless of elevation or temperature (something that can GREATLY affect a carb's performance).
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Old 03-06-2012, 11:10 PM
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I think I found out my problem on the leak. These studs (Pictured) are supposed to be where the studs in the block (also pictured) are supposed to be. I do not have these so I have nothing to screw the washer onto the studs therefore my intake manifold isn't properly sealing. Sorry if I explained it bad. The pictures should help.
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Old 03-08-2012, 08:41 PM
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Quote:
Originally Posted by 454C10
Since 77 datsun 280's came with efi, someone put that carb on (most likely a holley 390 cfm).


Need to check fuel pressure and make sure the carb linkage is working smoothly (since the linakge isn't stock anymore).
exactly what i was going to say
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