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Well my Midget made it home... Need Help!

RickB

Yoda
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Bone tired, must sleep.
Need lots of help with HIF-4 SU carbs, mine don't run right.
More tomorrow.
 
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RickB

RickB

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Re: Well my Midget made it home...

The carbs started out running VERY rich, putting out much smoke from the exhaust.
BillM started tuning them, they didn't want to respond to this very much.
After a few attempts we sat and thought about it, and I remembered the Facet fuel pump I installed for the Datsun carb had 4 to 6 pounds pressure, too much cor the SU's.
Bill quickly located a low pressure fuel pump and I installed it.
Things got better momentarily, but then started going bad again.
We put in a little gas from Bill's can and it still wouldn't run.
Quickly swapping in another fuel pump and the thing started again, but back to smoking.
The rear carb was over boarding, too much fuel going through it.
Bill tried adjusting and got it to about where I could maybe drive it and I took off.

Within several hundred yards I had to pull off, it was running so badly that I just couldn't go. I called Bill and he said to try richening both carbs, so I did that and it would take off again so I started out.
I barely made it to the nearest gas station and fueled up.
Between there and the freeway it was just running badly, but running.
I got on, driving in the far right lane with my flashers on.
I got off at High Point Way, about a mile, where there was a road I could take all the way home so I wouldn't be on the freeway.
The carbs changed to racing away, running roughly but high rpm.
I managed to shift between 3rd & 4th most of the way and after quite a while made it home.

So - now what to do?
I have only ever had the HS series carbs before, this type SU is new to me.
It may be that they are simply not usable as is. I really don't know.
I plan on going out today and trying to adjust them and see if I can get it to running.

Any pointers at all, things to look for, what to do next advice GREATLY appreciated.
 
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Re: Well my Midget made it home...

What type of manifold design?
 
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RickB

RickB

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Re: Well my Midget made it home...

The two 1.5" inlets branch to 4 individual inlets where they bolt up to the head.
Two round into four oval ports. There is a 'tube' between the two sides.
I can take some pics and post them here.
 

Billm

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Re: Well my Midget made it home...

Rick
Is the rear carb still dumping fuel? If it is then you need to open it up and clean the jet, if it isn't then you just need to set the mixtures correctly.
BillM
PS Glad that you made it home (before dark?)
 
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Re: Well my Midget made it home...

So the carb mounts level?
 
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RickB

RickB

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Re: Well my Midget made it home...

Hey Bill, right around (or little after) dark.
Strange drive home.
I'll try that.

Trevor, no they are at a an angle. I'll take some pics.
 
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RickB

RickB

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Re: Well my Midget made it home...

I went out and turned the key on, gas started coming out the front carb overflow.

Here are a couple pictures:
 

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RickB

RickB

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Re: Well my Midget made it home...

Another angle:
 

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Re: Well my Midget made it home...

you need air filters. Su's like a little restriction- I believe it helps with the pressure differential thing. I tried running like that with just rams. Didn't work as well as when i put some filter material over the rams. Of course the gas pouring out doesn't help. Sounds like you need to make sure your floats are not stuck. and the float height is set correctly.


m
 
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RickB

RickB

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Re: Well my Midget made it home...

Yes, filters are always good.
These problems are way more than what filters will solve, it's probably more about the floats and the pressures. I'm going to see if I can find my fuel pressure regulator and hook it up, see if that's it.
 
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RickB

RickB

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Re: Well my Midget made it home...

Notice there is a fuel feed hose that loops around to the back carb?
I'm looking and looking and looking and not seeing it until just now, the things have a hose that goes between the two carbs at the front, supposedly to feed fuel from the front to the back carb.
So why does this fuel line from the pump go to both carbs I was wondering?
I look and look at the diagram in the book and it just hits me - there's a fuel feed hose to the front carb but the back only has "breather pipe" and "vent hose" connections on the right side - no fuel feed in over there as the fuel feed in is on the left side of that carb!!

So - what happens when you feed fuel into the carb via the 'vent tube' or the 'breather pipe'?
Whatever it is, I will bet it isn't good!!!

Going out to make it look like the book right now. Will report soon.
 
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Re: Well my Midget made it home...

interesting. I would imagine it would cause flooding issues...

m
 
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RickB

RickB

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Re: Well my Midget made it home...

OMFG you have got to get yourself one of these!!!

Ok, backing up a bit...

So as you might imagine hooking up the fuel so it only goes where it should and doesn't backfeed into the VENT made everything way way better.
A little adjusting and OFF TO THE RACES!!!

Wow - the GX head and a pair of 1.5 inch carbs is WAY freaking better performance than the econo head and the little hitachi downdraft.

I take off from the line now like amazing and it just pulls and pulls and pulls.
This is nothing short of amazing!!

So - to summarize...
Datsun A15 motor with a GX performance head and a pair of SU's = AWESOME!!!

Add a 5 speed and maybe I'll just have to feel like I've died & gone to heaven.

Yeah, it's that good!
 

Pythias

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Re: Well my Midget made it home...

Congrats... makes the work almost worth it.
 
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RickB

RickB

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Re: Well my Midget made it home...

Well if you felt how it pulls now you'd likely say it was really really worth it!! :smile:
 

mrsprite

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Re: Well my Midget made it home...

RickB said:
Wow - the GX head and a pair of 1.5 inch carbs is WAY freaking better performance than the econo head and the little hitachi downdraft.

Whoa! How did I miss this?? So you found a GX head and carbies?? Very nice. I love pulling 3rd gear to redline.......like you said, it just pulls and pulls and pulls.

Oh yeah....you definitely need the 5-speed now! :smile:
 
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RickB

RickB

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Re: Well my Midget made it home...

It's really night and day different. I thought I'd notice something, but wow - not this much. I haven't even been on the freeway yet, just driving around town so far!
 

nomad

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Re: Well my Midget made it home...

Rick: Did you just change head or cams as well? Where did you come up with the GX head and manifold? (I want one!!!)
Kurt.
 
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RickB

RickB

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Re: Well my Midget made it home...

Rare as hens teeth, you got to keep looking - watch craigs list and ebay - you never know...

However, our good friend BillM might be able to hook you up...
The harder thing to find is the intake manifold.
I got really lucky!!
 
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