I don't know, seems the introduction on non-atomized fuel in an uncontrolled fasion would be a problem. :shrug: If that is the case and fuel does get drawn through the accel pump, what's the purpose of the acclerating pump discharge needle?

 

One question, where does any fuel that comes out the accel nozzles go? Right thru the venturis where it gets atomize, just like any fuel that comes thru the carb (except for idle curcuit) accel, main jets and power valve . So what is the problem? And it's max flow rate is controlled by the nozzles size and the amount of air flow thru the carb. The needle works fine (they went to the needle (more weight) from just a check ball because this used to be a real problem), but again it is a metal to metal seal or lack there of and fuel will flow. I've seen it expecially on bigger CID engines and small bore carbs with high air flow rates.

 

http://www.stockcarracing.com/techar...08_carb_cures/

 

I really don't think a venturi is going to atomize fuel droplets that are already in the air stream. Liquids are atomized by forcing them through a small opening. Look at any pump squirt bottle. The accel pump nozzle is much larger relative to the openings in the booster venturis.

The fuel droplets from the nozzles will be larger and just pass through the venturi. The low pressure in the venturi will not atomize anything. As a matter of fact, the low pressure works against atomization. Watch the weather report tonight. Note where the areas of low pressure are and then where the areas of cloud cover or storms are. Clouds are liquid that has fallen out of suspension. High pressure regions may have plenty of moisture for clouds (high humidity day) but no clouds due to the high pressure system. When a low pressure system moves through that same area, all the water falls out of suspension. I'll bet the large droplets fall straght to the plenum floor where they vaporize due to the heat of the exhaust crossover under the carb.

I'm not saying it (pulling fuel from the accel pump) doesn't happen. I'm saying I don't think it should happen. And it seems jetting the carb to compensate for this is a crutch or a band-aid fix.

Oh, and on the purpose of the discharge needle, nevermind. I think I've figured it out on my own.

 

I almost said something snide, but I'm on my better behavior today so the smart mouth is off for now. First off the carb and intake system does not work like weather does as the air velocity never slows down to a stop. When the air flow speeds up thru the venturi (it has to, it's physics) it stirs things up pretty good (it can even go super sonic which really atomize the fuel). Have you ever run a car on a chassis dyno and looked down the carb at WOT? The fuel is pouring out of the boosters and sure ain't atomized at that point. That's what the venturis do (the speed up and slow down of the air stream) in addition to creating the suction to pull the fuel in the first place. I went to a Holley tech course a million years ago, but carb basics hasn't changed since then. As to whether pull over should happen, I agree with you. Does it happen, he!! yes it does. If you have a race car the accel system ( use to run my 428CJ in the race car with a 406 2X3 with no needle in the accell system to richen the big end a bit when the weather conditions required it and it was easier than changing jets) is dumping extra fuel it is no big thing, but for a street car it is a no-no as far as mileage goes (even if you spend ever little time at WOT). Changing the jets to compensate would be no different than putting the window style power valve into a carb designed and set up for an old style power valve. You jet leaner to compensate for the extra fuel. On a street car I would fix the accel system though.

 

Physics is physics. Be it in the atmosphere or in a carb. I stand by the statement that lower pressure air will carry less liquid.

The rest we seem to almost agree on.

On Edit:

Holley Tech support responded with this:

Hi,
thanks for your e-mail
it can use either a blunt weight and a ball under it
or a pointed wieght and no ball
either set up will work
all we offer is the pointed weight
it is part # 121-5
the pump should only put out fuel when the gas pedal is moving the
check weight makes this happen
Thanks Ricky

 

Sometimes you guys act like a bunch of middle school kids. I'm an old Detroit street racer. know all the words in the language including the nasty ones, I know all the little characters on the keyboard, and I know how to interpret the first letter and following dashes that some are fond of. And none of that crap (see I used one too) is adding anything to this thread, nor helping anyone understand their tuning issues, nor the intricacies of their carb. With eight years at Holley and twelve at Federal-Mogul (they own Carter) its a fair bet that I have more fuel system experience than most folks here.

Pull over enrichment (POE) is a very real and very valid tuning tool - - even if you don't like the sound of it. You are using it in most every non-modified Holley and Q-Jet. Even if the tech kid at Holley don't believe it exists (the old design engineers from Holley that truly developed that carb have long since retired). I think that ONE guy is left from the original Holley headquarters engineering team from the 80s and 90s...

First lets cover the Q-Jet. Every one of them has a pair of POE holes on the secondary side. Most of them are just above the secondary air doors - - but the really cool Q-Jets (W30 442 and 429CJ Ford) have them below the door for a quicker shot. The POE holes serve as a non-mechanical accelerator pump to help cover the big hole in the transitional fuel curve when the secondaries open.

Now lets chat about the Holleys. There are three distinct types of pump squirter. Plain, brass tube extended, and surprise - "anti-pullover". The difference between the first two is not targeting as some think. Both are targeted by original design to hit the high side of a booster. The difference is that the extended tube is further into the airstream and will pick up a stronger signal from passing airflow, initiating pullover earlier in the flow curve. The anti-pullover is not often seen - - but it has an extra "wall" around the squirter with pass holes for the pump shot to go through. The wall insulates the squirter itself from the airstream effectively killing pullover. In addition with OE calibrations you might find a variety of discharge check valves used to slow or speed the initiation of pullover flow - round ball, steel, brass, or aluminum needles...all the aftermarket supports is the needle now.

Now that you have learned that pullover exists (actually it always existed - it was designed into the carb in 1957) don't argue and fight about it - - learn to use it to your advantage.

 

**************

 

Hey, you guys are all !@#$. You guys hijacked my thread.

Mike

 

So how you making out?

 

If this is all it takes to screw your life up..............well, you better get some sort of real life to live.

 

Well, with all this this talk, now I'm questioning which carb I should run.(Actually I'm 100% certain I'm runnin a Holley)

I've got me a 4 day weekend coming up, so the truck is gonna be moving on it's own power by Monday hopefully. I ain't gonna be able to work on it til Saturday morning, but want to pressure wash engine compartment, then spray some flat balck in there, then drop in the motor. I'm putting headers on it too and never have dealt with them, so hopefully things will go smoothly dropping it in. I'm hoping I ain't gotta futs with the headers too much, while I'm trying to line up the torq-converter. We'll see.

BTW, that'a another question I had for you guys out there. I ain't gonna have any exhaust on the truck, besides the headers. Is that a problem. I heard you can burn valves up that way. Is that true? Shoudl I not run it until I get some exhaust on it? I don't think I can modify existing exhaust that hooked up to logs. I guess, I thought my intentions were to get her going good, drive er on down to the local muffler shop and have the guy set me up. Not a good idea? Should I trailer instead? It's about 10 miles to town.

As much as all you correct eachother, I can at least say this much.....You guys are a plethora of information, and I appreciate your guys' knowledge. Thanks!

Mike

 

Actually, you haven't lived yet, untill you've fired a new engine off with open headers ( AND I KNOW EVERYONE HERE WILL AGREE ON THIS POINT ) No, you're not going to burn anything, cept maybe your next door neighbor's temper, if he happens to like quiet mornings , unless he's a bona-fide redneck (then he'll come runnin). If you want to make the engine to transmission marriage go smoother, take 4 long, old style small block head bolts, the ones with the straight shank, and cut the heads off. Chamfer the ends. Also helps to grind a screw driver slot into em to help loosed em after your done. Screw these into 4 of the bell housing holes (2 per side) in the block. Drop the engine in, align the studs with the corrosponding holes in the bell. Align the converter studs to the flexplate. Push the engine onto the bell. Remove the studs and replace them with the belll-bolts. Works smoother than this thread has gone. GUARANTEED ! I've done a couple of engine installs using this method, solo. No other help (hands) needed.

 

SMOOTHER THAN THIS THREAD!!!Holy Crap……I need to get me some small block head bolts.Problem is, there are no small blocks laying around.Actually there are a couple, but I don’t think the old man would like to under the hood of his Falcons.Especially, his 64 sprint.I think he’d shoot me. Also, I've got me an engine hoist, rather than a cherry picker, so things go relatively smooth with it.

As far as neighbors go, we ain’t got any for at least a half mile, so I think we’re good there.The closest neighbor to my folks, is well…….MY HOUSE!I’ll just be sure to have me some ear plugs and tell the old man to shut down his hearing aids. :thumbsup:<O</O

 

If you can 't get head bolts, run down to the store and get 4 long (4-6") 7/16NC bolts and cut the heads off them. I just use the head bolts, cause I happened to have em layin around. Trust me ( where you heard THAT before? ) even with a hoist, it still makes things go together easier.