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14 minutes ago, rcv said:

 

@siteunseen I just read through your linked post, and think I get it. You’re using an electric fuel pump to push fuel through the float while it sits on a glass. Then you just measure the fuel level in the glass when it stops, right? I’m I reading the FSM right when it says the fuel level should be 23mm from the roof of the lid? I don’t have an electric pump, but any reason it wouldn’t work if I pull off my mechanical pump and actuate it manually?

Yes. I scratched a line in a glass jar that was 23mm from the lid's roof then hooked up an old pump and got them dead on. Never looked back, they have been rock solid for 4 years now????

The jar was one of these from my grocery store.

Hormel Ground Formed & Sliced Dried Beef, 2.5 oz (Pack of 12)

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If you have any 1/4 drive sockets you can fit one under the tang and use it to bend the natural hump back in. If you don't have a socket you'll think of something that will work.

Under the tang in the red circle.

image.png

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Well, no Hormel Dried Beef at the grocery store, but I did find a nice straight glass and a big flat trivet that can live in the garage. 

75A86889-89E7-43BB-956F-B968DB352957.jpeg

Just to be clear on the measurements, 23mm is from the roof of the bowl lid right? That lid is recessed by 3mm, plus I have a 1.5mm piece of plastic it’s sitting in, so I’ll need fuel at 23 - 3 - 1.5 = 18.5mm below the top of my glass right?

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Math escapes me on Sundays, my only off day sort of, my shortest work day. But it sounds like you have it.

I got lucky with that jar. It's barely larger than the float chamber.

20201011_162415.jpg

And yes from the roof. This picture is dissceiving. LOL

 

Edited by siteunseen

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Speaking of math escaping us, I may have inhaled too much of these gasoline fumes. 

Does the diameter of my measuring vessel matter? My cup is around 80mm wide, but it shouldn’t matter as long as I’m filling slow and steady right? Archimedes is rolling in his grave right now. 
 

I’ve got my tab bent really damned low and  I’ve finally gotten to my 18.5 mark, but the float is pretty much topped out against the lid. Doesn’t seem right at all, and worries me that any minor variation and I’ll start spewing gasoline out of my bowls. 
 

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Is that water or gas? Seems like i read it makes a difference but DANG! thats way off from mine. I have know idea Sir, sorry. It should sit level in my opinion. Another thought. Maybe your glass is so much wider allowing it to do that? The float chambers might keep it level because of their smaller diameter. You need some dried beef! LOL

DSC01679.thumb.JPG.2225dee750287abaf24cfdfa6d4efef2.JPG.jpg

 

 

 

 

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I just noticed you don't have the needle valves like I have. Are those the original ones from 100 years ago? I don't think they are. OE Nissan has a rounded tip. Your's are squared off. Maybe they were from a closed Z supplier now, Black Dragon? They sold rebuild kits.

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Yup it’s gas. I tried my old floats/valves/lid combos from my original carbs and got the same basic results. I’m beginning to think maybe my adjustment factor is off?

These are 4-screw carbs if that makes any difference. 

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I found a thread with the different valves and something I totally forgot about. '72s have different length mounting ears for the floats. Fronts are longer or deeper to make up for sloshing back on acceleration. You have to use multipile washers on the front valve. They call it stacking.

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4 minutes ago, rcv said:

Yup it’s gas. I tried my old floats/valves/lid combos from my original carbs and got the same basic results. I’m beginning to think maybe my adjustment factor is off?

These are 4-screw carbs if that makes any difference. 

Okay the 4 screws are the same length front and rear. No stacking washers.

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Well if it’s not one thing it’s another. 
 

I got the floats looking ok-ish and reinstalled them in the car.  Turned the key and nothing.  I pulled the line from the bowl inlet and turned the key to make sure the pump was at least working, and got nothing out of the fuel line.  So, it looks like my brand new mechanical pump is dead now. 
 

The bad news is that I disconnected the input line to the pump and sucked some fuel through my Mighty Vac and what came out looked like a nice aged scotch. I had drained and refilled the tank about two weeks ago, so this must mean that the inside is absolutely disgusting and some of that nastiness must have peeled off and caused an aneurysm in my pump. I was avoiding dropping the tank, but it looks like that was a bad move. 
 

Looks like I’ll be dropping the tank next weekend and getting it cleaned out. What a day. 
 

38A10F72-63B5-418F-9947-BD18ACD346F9.jpeg

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I pulled off my fuel tank today and dropped it off at a shop to get cleaned out and then have some Red Kote applied to the inside, and black paint applied to the outside.   It should be done in a week or two.  I'm also going to order some new stainless lines etc so I can actually do this thing right.  Hopefully I'll be back to messing with the floats in a month.  

 

I also ordered some of that Hormel Dried Beef on Amazon for when I get back to calibrating the float levels.  Any recipe recommendations @siteunseen or should I just feed it to the dog?

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Here's what I do.

Dried beef coated with cream cheese.

Spear cut dill picles laid on top.

Roll it up like a cigarette or doobie, whatever you kids are into these days.

Cut them into 1" sections. Serve cold with bloody Mary's.

You will be remembered forever as the guy that has good get-togethers. Party on Wayne!

pickle-roll-up-recipe.jpg

 

 

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Well I still haven’t gotten my tank back, but I ordered a set of Float Syncs from @Randalla and spent an hour or so getting a “static” float level.  The float syncs are really nice and made it a snap to get the levels set. 

I used a small squirt bottle to pour fuel into the input line with a funnel, and then just rotated the float sync to drain it back out into my bottle to reset.  Really interested to see how well the “static” float level corresponds to the levels when the engine is actually running.

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Well, it's been almost a month since my last update.  The fuel tank is back in, and besides a quick adventure with a blown heater hose I've still been struggling with this damn fuel system.  It looks like I've just had my second mechanical fuel pump quit on me in a month.  It seems like everyone has had some issues with these reproduction pumps, but two in a month sounds like very bad luck.  My first though was that my return line was plugged and putting too much backpressure on the pump, but I was able to blow through the return without too much resistance.  Can anyone think of what else could be causing these pumps to die, or is that just how it goes with these pumps?

I'm strongly considering just biting the bullet and going with an electric pump (probably this K&N one) unless someone wants to talk me out of it.

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5 hours ago, rcv said:

 two in a month sounds like very bad luck. 

Two in a month is bad design/bad parts.

 

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2 hours ago, zKars said:

My goto electric pump is this one

Looks nice, I've never heard of these guys before. They recommend mounting vertically, do you have any pics of how you mounted it on your car?

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Note: There is a need to have fuel pressure on the valve for accuracy.  Column of water or fuel in a vertical hose can do this w/o needing a pump.

 

You can also idle the car then shut it off and measure fuel bowl level.

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5 minutes ago, 240260280 said:

Note: There is a need to have fuel pressure on the valve for accuracy.  Column of water or fuel in a vertical hose can do this w/o needing a pump.

 

You can also idle the car then shut it off and measure fuel bowl level.

Sorry, not sure I follow. I've been using Randalla's Float Sync's during all of my tuning, which were really helpful in immediately diagnosing that my float bowls were drying out.

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Measuring the fuel level in a small jar by pouring in the top is brilliant an is  great for ensuring both fuel levels are exactly the same but this is basically for 0psi fuel pressure.

If you apply 3.5 to 4psi, you will find the valve opens and the fuel level goes up higher.  Measuring on a running car or with a head of fuel does not have this issue.

Edited by 240260280

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