Dual quads versus big hammer!!!...

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j par said:
I just got off the phone with the machine shop where my heads are at and was talking to Ted and the problem of describing to him is what he called fuel standoff.. where when I give it fuel it's not shooting down it's shooting up. I get the lean condition and I can see the fuel traveling upwards on the carburetor.. well I see the AF gauge slam upwards as well momentarily..
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Ok, so fuel stand off. I've seen it, but never in a situation like this.

I'm thinking maybe try taking off the 2 inch spacers and see what that does for standoff.

If it helps, you are going the right direction. I don't have a standoff issue, but I am having some reversion issues (that is my working hypothesis at the moment) and I bought an anti shear plate to try and correct what may not be a problem.

I'll post some pictures of it and my intake in a bit. You just can't bolt them on. But it may be worth looking into.
 
yellow rose said:
Ok, so fuel stand off. I've seen it, but never in a situation like this.

I'm thinking maybe try taking off the 2 inch spacers and see what that does for standoff.

If it helps, you are going the right direction. I don't have a standoff issue, but I am having some reversion issues (that is my working hypothesis at the moment) and I bought an anti shear plate to try and correct what may not be a problem.

I'll post some pictures of it and my intake in a bit. You just can't bolt them on. But it may be worth looking into.
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You know I talked to Ken and he said the 2in spacers would help the situation not make it worse. Or at least that was his thought. That's where I was headed next.. I just tried progressive linkage and that didn't do crap and I don't like it anyways..
 
j par said:
You know I talked to Ken and he said the 2in spacers would help the situation not make it worse. Or at least that was his thought. That's where I was headed next.. I just tried progressive linkage and that didn't do crap and I don't like it anyways..
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I agree. You usually see stand off with stack injectors or individual runner carb stuff and not with a plenum.

That said, I agree the 2 inch spacers should help with any stand off as the plenum dampens those reversion pulses.

I can honestly say I have no idea what happens with reversion and stand off if the plenum volume gets too big. I don't even know that you can get too much plenum volume.

At this point, it's kind of spit balling.

Obviously, if you wanted to eliminate the spacers as the issue for the stand off you could swap the eddies on there and see if it goes away.
 
yellow rose said:
I agree. You usually see stand off with stack injectors or individual runner carb stuff and not with a plenum.

That said, I agree the 2 inch spacers should help with any stand off as the plenum dampens those reversion pulses.

I can honestly say I have no idea what happens with reversion and stand off if the plenum volume gets too big. I don't even know that you can get too much plenum volume.

At this point, it's kind of spit balling.

Obviously, if you wanted to eliminate the spacers as the issue for the stand off you could swap the eddies on there and see if it goes away.
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Probably easier to take the spacers out at this point but I'm giving her another try here...
 
I have been on a learning curve with my 6-pack multi carburetors my system runs off a 350 CFM Center carb as you all know but when the fat sisters kick in the motor will handle it as long as the RPMs are high enough to keep Port velocity up. With the chance of oversimplifying the motor must always wait on the carburetor and never the other way around. The quickest way to develop a hesitation with multiple carburetors is too slow Port velocity down, and that's very easy to do withCFM capabilities are twice what a single carburetor brings on a secondary circuit. just my two cents
 
Well when it's good it's great!
I gave it a little rev and dump the clutch and held it down and she ignited the tires no problem..
Still AF gauge is Rich all over the place except for when you punch it it goes lean real quick..
What I thought was odd was the squirt nozzles are open at the top. they squirt and spray down but I wonder how that works under power? As I see that big puddle all the way across the top of the front inside of carburetor..
Old pointed out here in the picture where I see the puddle all the way across...
IMG_20200309_140735.jpg
 
What I find odd is the tops of the nozzles are wide open and it seems like that's where all the fuel is coming from? The bottom corners of the nozzles have the holes that squirt out and they do just fine free revving it.
IMG_20200309_140735.jpg
 
wow great looking system I didn't realize those where the Demon carburetors you had those should work great with your system
 
Are you driving without filters while doing this tuning?

The choke horns might be acting like a motorcycle windshield and the buffetting is sucking fuel up out of the carb...

Those types of squirter are made to prevent air from sucking fuel through the Nozzle when you don't want it to.
 
j par said:
If I change the carbs I'll just put the Edelbrocks back on.
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When you get to that point I will come to your rescue. I am such a prince-of-a-fellow, I will remove those nasty little Demons from your existence and only charge you $10 apiece for disposal costs. That will get you enough Mountain Dew to calm your poor frazzled nerves. :D
 
Phreakish said:
Are you driving without filters while doing this tuning?

The choke horns might be acting like a motorcycle windshield and the buffetting is sucking fuel up out of the carb...

Those types of squirter are made to prevent air from sucking fuel through the Nozzle when you don't want it to.
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Yes and no. I am driving with the filters off and on I kind of got that as well. Also I took the air doors off because they are locked open anyways and get in the way of changing the metering rods and Springs... The car actually idols and runs Great. There's no need for a choke just hold the throttle open for a little bit and it starts idling after a minute.. It fires right up and shuts right off..
But if it wasn't for taking the air doors off and the air filters I would have never seen that fuel inversion...
 
Gotcha. Was just curious. Running it both ways is definitely the only way to get to the root of it and nothing wrong with removing the choke door. But I know filter versus not can cause issues sometimes, but so long as anything "close" is also checked with filters on then it shouldn't be a problem.

I ran across at least one other discussion elsewhere (non Mopar related) that mentioned tunnel rams sometimes see worse standoff despite the plenum because the ports can still have a pretty straight shot at the venturis and that it tended to be at lower revs with tunnel Rams and narrower LSAs which seems to match your setup.

No one had any clue on a solution though, LOL.

Anti reversion plates seem like the obvious thing to try, but throwing money at a maybe can suck.
 
I showed this picture Street Demon discharge nozzle..
IMG_20200309_140735.jpg

Notice those two big openings on either side as you can look down through them right into the discharge holes? seems to me this is where the fuel is getting pumped up words and out?
Here's a picture from Summit of a demon discharge nozzle and it's capped off and only can go the One direction straight down in.. my thought is to order a couple of these..??
Screenshot_20200309-213040.png
Screenshot_20200309-212642.png
 
The ones with the opening on top are supposed to prevent "pump pullover" which is when the high velocity air sucks fuel through the accel pump.

Might be worth trying the conventional type, but you may wind up drawing more fuel through them at higher revs... Hard sayin' not knowin'
 
Phreakish said:
The ones with the opening on top are supposed to prevent "pump pullover" which is when the high velocity air sucks fuel through the accel pump.

Might be worth trying the conventional type, but you may wind up drawing more fuel through them at higher revs... Hard sayin' not knowin'
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Yeah very hard saying. I was going to try possibly try the ones with the brass nozzles on them? Like this...
Screenshot_20200309-222406.png
 
I'd say it's worth a shot, but it's easy for me to spend money that isn't mine..

If you do wind up using those and pull fuel from the pump nozzle, it should be possible to tune around it but could be difficult. I would think the brass tube style would help get the fuel into the faster air and atomize better, but I've been wrong before..

Never had to try different nozzles and squirter myself, so hopefully someone with more knowledge chimes in.
 
Non-helpful post #2:

I wonder if enough $$$ has been spent yet on Demon tuning goodies........that a matching carb to one or the other of the original carbs could have been bought and a kit put in it for the same money.
Of course....... in the end that would turn out to be very low cost, since after you had the matching carb....... you’d have the non-matching one to sell(and get the bulk..... or use on another project.
(Edit: I just went and looked on ebag....... not a lot of good deals on those carbs right now....... and a lot of it seemed like it was priced in la-la land)

Pop quiz....... changing the squirter/nozzle hole size technically does what???
 
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PRH said:
Non-helpful post #2:

I wonder if enough $$$ has been spent yet on Demon tuning goodies........that a matching carb to one or the other of the original carbs could have been bought and a kit put in it for the same money.
Of course....... in the end that would turn out to be very low cost, since after you had the matching carb....... you’d have the non-matching one to sell(and get the bulk..... or use on another project.

Pop quiz....... changing the squirter/nozzle hole size technically does what???
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Also another woulda coulda shoulda post LOL yes thought about and even tried matching my old carburetors.. but they worked well together and the other ones I've tried to match didn't.... And to answer your first non helpful question LOL stupid me thinking since our local part store had a Street Demon for sale and their glass case they would actually have parts for it LOL my bad.. it's really just the primary Jets and metering rods that are stand-alone for these carburetors. But they're very cheap. I can't remember once putting a custom part on my car and it not costing me 25 to 50% of the original cost more to make it work. (Speedmaster heads are in the shop now LOL and let's not forget about the special studs and all four gaskets) I'm definitely less than a hundred bucks and extra tune up parts but who buys carburetors that are in perfect tune?
And as far as buying the same old carburetors everybody else has that's not what I want for my car. Who has beaver skin headliner? Who has alligator skin seats? Who has snakeskin back deck lid?.. so far I seen one car or actually one motor on the internet that had dual Street demons. I actually talked to the guy who did that article yesterday. again all their work is done kind of like yours on a dyno...
To answer your question I haven't had much of a change with the squirt nozzles but again what I wanted to do was change the design of the nozzle itself. Not giving it an opportunity to go upwards...
Remember the car starts and turns off just fine and throttles on great but jumping on it at a low speed is where I'm having my issues. It's not a normal driving condition that I'm having a problem with..
In the end I still haven't came close to spending what it would cost for two normal tune up kits...
 
Heads at the machine shop?

After all that talk about how jewelry-like they were, and how you were gonna look them over yourself and run them ootb?

I’m shocked!!
 
PRH said:
Heads at the machine shop?

After all that talk about how jewelry-like they were, and how you were gonna look them over yourself and run them ootb?

I’m shocked!!
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They didn't lose their jewelry likeness LOL I've been fortunate to have plenty of work and have a couple extra nickels to rub together so I broke the news to my machine shop that I bought offshore heads. He didn't throw a fit but said he'd take a look at them. He said they looked pretty good as well... But we'll see when he opens them up. Initially he told me a couple hundred bucks and I was cool with that. Of course that's for a multi angle valve job... But that is for another thread and maybe we ought to get on with tuning these carburetors...
 
I ordered a couple of those Holley squirter nozzles. they should have them at the local parts store when I get off work...
 
Gurus running for cover...... funny.

It’s like, “hey I bought stuff that’s not really right, but it looks cool so I’m gonna run it. Can you help me?”

I have no problem with people doing whatever they want to their cars.
But when it’s something I feel is just the wrong way to go about it...... in the end you’re probably better off getting advice from someone who actually believes you can get completely satisfactory results.
Not from a doubter...... which in this case....... I am.

Also, for me...... carb tuning is a tactile thing.
I need to be there, hands on with it, to see how the motor responds to the changes.
How you interpret the results from a change may not be at all how I interpret the results from a change.
And how the results are interpreted....... form the decisions on what to do next.
 
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