Thanks this will be useful.
Holley/Demon Carb stumble
- Thread starter Cudafever
- Start date
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Thanks this will be useful.
Here's one on converting an E85 back to pump gas.
Alcohol carburetor/blocks return to gasoline use?...
Might be more. Seem like the concern was in the booster's passage, not the angle.
See if this application being discussed below looks similar to yours.
If so, then I'm with Mike - I'd start where Mark recommends, which is IFRs oround .035 - .036. (post 13.)
Annular HP1000 Emulsion Setup
Some discussion on QF 850s
Quick Fuel SS850 accel pump cams
Alcohol carburetor/blocks return to gasoline use?...
Might be more. Seem like the concern was in the booster's passage, not the angle.
See if this application being discussed below looks similar to yours.
If so, then I'm with Mike - I'd start where Mark recommends, which is IFRs oround .035 - .036. (post 13.)
Annular HP1000 Emulsion Setup
Some discussion on QF 850s
Quick Fuel SS850 accel pump cams
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I will read all three of them and thank you.
I just got "HOLLEY" Carburetors, Manifolds @ Fuel Injection. By Mike urich @ Bill Fisher.
So i can start milling threw that as well.
Post back later what you think.I will read all three of them and thank you.
I just got "HOLLEY" Carburetors, Manifolds @ Fuel Injection. By Mike urich @ Bill Fisher.
So i can start milling threw that as well.
One secret to keep in mind, not mentioned in the book, is about about air:fuel ratios.
As we gently load an engine by increasing the throttle and letting the clutch grab, AFR should get leaner!
Arrow points to increasing load on the engine coming off of idle. F is fuel:air ratio. Inverse that and you'll get AFR but the exact number is not important. Every engine is a little different.
The point is the engine runs best with mixture going leaner as load increase, unless near maximum acceleration or load. Then it needs richer again.
from Walter B. Larew, Carburetors and Carburetion
Big secret.
yellow rose
Overnight Sensation
yellow rose
Overnight Sensation
You spend 1k on a carb and you may (maybe will have to change a jet or pump cam.
If you really want to get some on the phone help with a guy who will give you the shirt off his back, call Dom at Thumpr carbs. I class him with people like PHR, Mike at B3 and Chad Spier. When those guys are talking, I'm taking notes. Or Kevin Johnson. Those guys are giving you the best they can.
Dom will do the same. He is more than willing to talk you through some of the tune up stuff. In fact, I'm calling him in the morning to order some stuff. He may be able to sell you a couple of BLP blocks with his tune up in it and bolt them on and go. He blueprints all his stuff.
PM me if you want his number. Hell, if he answers he may help you today. I've got a 3 circuit Dominator sitting here I want converted to 2 circuit and a booster and Venturi change. That's a next spring deal.
Intermediate circuits.
Not spent much time learning about them. Used on some Chrysler emissions carbs (Because they ran very lean idle circuits and this let them seperate the transition slot so it had its own circuit).
All I can do here is refer to Tuner. He says the development on Dominators was for independent runner intakes.
Independant Runner intake with Split 4500
3 circuit blocks on 4150
yellow rose
Overnight Sensation
PM sent to cudafever
yellow rose
Overnight Sensation
that P in front just threw me off IAB
PRH
Well-Known Member
Here’s a couple more......
What’s been referred to in this thread as the “kill bleed”, I call the “siphon break”.
To me, the kill bleed is the bleed used in the vacuum secondary opening system.
What is referred to as the “angle channel”, I learned as the “crossover leg”.
However, googling that turns up nothing....... so that must not be a very popular term for it.
What’s been referred to in this thread as the “kill bleed”, I call the “siphon break”.
To me, the kill bleed is the bleed used in the vacuum secondary opening system.
What is referred to as the “angle channel”, I learned as the “crossover leg”.
However, googling that turns up nothing....... so that must not be a very popular term for it.
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So I take it you got the carb dialed in.
Nope got it all torn apart to do some measuring and install a new Proform base plate, Rear float and Jet extensions.
So Mitty Demon with Proform base and main body, so far.
Here is the spread sheet with all the data i have discovered column B is the current or latest setup. I'm going back to the jetting that was popping and banging. If it does it again i will jet it back up. But I want to see how it will act with 4 jet sizes down from Stock Proform Set up.(because i live at 6600 feet) should need less main jet.
If it pops and bangs i'm going to half to except that the demon metering block was calibrated with larger jets then normal and go back up to the jetting that stopped the lean pop.
The Super Sucker is just to help out velocity for a carb that's to big(slow velocity) for my application. One of the things that Dom felt would help.
Woops Primary IFR is the same as the rear at .054"
So Mitty Demon with Proform base and main body, so far.
Here is the spread sheet with all the data i have discovered column B is the current or latest setup. I'm going back to the jetting that was popping and banging. If it does it again i will jet it back up. But I want to see how it will act with 4 jet sizes down from Stock Proform Set up.(because i live at 6600 feet) should need less main jet.
If it pops and bangs i'm going to half to except that the demon metering block was calibrated with larger jets then normal and go back up to the jetting that stopped the lean pop.
The Super Sucker is just to help out velocity for a carb that's to big(slow velocity) for my application. One of the things that Dom felt would help.
Woops Primary IFR is the same as the rear at .054"
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j par
Well-hung Member
How much is a super sucker?
PRH
Well-Known Member
I’m pretty sure that’s not what you mean to say.
cookietruck
Well-Known Member
i think you have your idle bleed and main bleed mixed up on the primary side on that chart.
That's a big drop. I'd play it safer and go 2 jets.
If its too rich, worst case is foul the plugs bad.
Too lean at WOT, I'd be afraid of burning a piston. Maybe that depends somwhat on the timing but I'd play it safe.
.029/.029/.029
IMO too little restriction on the air into the wells.
Start with less, change if needed.
Here's what weird looks like.
When AFR looks like this, jetting isn't going to fix it.
First thing I did when returning to the dyno was confirm what I suspected, which was the secondaries were the main issue.
Take a look at the AFR curves starting at 4000 rpm, which is where 3rd gear full WOT begins.
AFR for primaries is flat. We can jet up or down within reason and its going to stay flat.
AFR with secondaries looks goes lean and rich and lean again like a yo-yo.
So clearly I need to fix the seconday curve. Where to start?
AFR above was picked picked up with a tailpipe sniffer.
Lets look at these runs on a logger (WBO2 in a bung) for a little more speed and detail.
The first thing we notice is that its going lean as the secondary throttle open, and then goes rich.
This is classic "too many" or "too large" holes from the air well.
There is also the possibility it relates to the secondary idle system. H'm. After all there's little time at WOT for anything to stabalize.
Finally, there is a long drift lean from 4750 rpm (13.7 seconds) to 5800 rpm.
My logic has been this way.
The drift at the high rpms is probably main air bleed. So first experiment should have been smaller SMAB (shove some wires in).
But I didn't have the sizes needed with me. Ended up just switching around the e-hole I blocked with only little effect.
Now I've got it set up and ready to test again.
I'm thinking it will be flatter, and probably richer than best power. But I'm not going to jet leaner until I see that lean drift go away!
As fate has had it, I haven't been able to get on a dyno or the 1/4 mile with a logger since then.
And now the car headers - although I don't think that will effect the curve - but of course I want to see what the new ET, and Mph are.
PS. The MABs can effect the initiation of fuel flow. It's just that their strongest effect is at higher rpms. Which way going larger or smaller with the bleed will effect lower rpm AFR, if at all, is pretty hard to know without tons of experience and notes. (Don't look at me, I just tinker a little and see what happens)
Tuner posted:
Graph showing Main and Emulsion Bleed behavior from Edward F. Obert's book, Internal Combustion Engines.
Holes A and B are "Emulsion" bleeds.
D is the Main Air Bleed.
This is a generalized description of carb bleed behavior. Venturi area relative to main circuit flow path area and engine air flow range affect these characteristics.
Tuner posted:
Graph showing Main and Emulsion Bleed behavior from Edward F. Obert's book, Internal Combustion Engines.
Holes A and B are "Emulsion" bleeds.
D is the Main Air Bleed.
This is a generalized description of carb bleed behavior. Venturi area relative to main circuit flow path area and engine air flow range affect these characteristics.
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