This discussion has a good explanation from Tuner on the advantage of a lower location IFR .
http://speedtalk.com/forum/viewtopic.php?p=452681
Glenn

Thank you Tandyman, much appreciated. I just had a simple question and wanted to hear from one side or the other. Tuner gave an excellent explanation in that link as to what he prefers with good info as to why.

That's all I was looking for, someone to provide a good reason for one or the other. As I said, I'm not bias either way, just looking for good info. There was no need for the attacks from Tom about something he knows nothing about.

Thank you Tandyman, I could have posted the same info (thread link that you did) but chose to let others pass on the info to Formulajones. The info I posted in Post 399 came from a document years ago and a discussion that Tuner and I had about 10 years ago.

I have not spoken to Mark much but have had many long phone calls with Tuner where we discussed carbs and how they actually worked. Tuner has gone by several names in the different Forums" at least 3 that I am aware of.

Tom V.

This thread http://forums.maxperformanceinc.com/...71#post5829271

Had a post or two from Tuner I believe. He goes by "YETI" on the Yellow Bullet Forums.
Worth reading some of his other posts. Very Good Guy and we have had many long telephone conversations over the years on how carbs actually work.

Thanks again Tandyman.

Tom V.

ps The Link in Post #2 by Yeti on YB to the Holley Carb info gives a Great picture of the Johnson Linkage vs the Double Pumper Linkage.
I have been trying to find a good link to that picture comparison for a long time. It was worth having this discussion the last couple of days.

I told you that the lower position was the better position for the IFRs.

You chose not to believe that. You also chose to post the statement above.
I actually do believe that I have a bit more experience with Holley carbs and how they actually work whether you say "I know nothing about them" or not. Good Day.

Tom V.

jmarkaudio wrote:

"I'm beginning to wonder about the onslaught of new members (or the same person) that keeps arguing the point." Same situation here.

"Most engines don't need 5 emulsion bleeds and by far most guys and gals don't know what to do with them any way. Lower power valve channels may or may not improve performance or the fuel curve, in most cases it doesn't.

You can get 100% of the performance on 98% of the applications with a cast block"

90+% of the guys in the Street Section want to run their Q-jet Carb, their Tri-Power Carbs, or their AFB Carb(s). The few "Holley Guys" for the most part have read a lot of Hot Rod articles or have paid the $$$$ to someone like the Western Michigan Guy who builds Holleys. We have a guy in the Race Section who ran both the Western Michigan Guys carb and a Barry Grant carb (that the Racer owned) and was actually quicker with the BG carb. Bye Bye $$$$.

So Formulajones, you just wanted to learn but you did not want to learn from me.
I could have posted the same info as Tandyman but sometimes it is better if you stay out of the debate and let others prove the point for you. Back on Holley Carb Info another time.

Tom V.

And if you are selling a "DZ" Holley Carb to a Chebby Guy and say it is "all correct", and it has the high mount IFRs you are lying to him
as DZ carbs were never built with the High Mount IFRs. When you have all of the build sheets for the Performance Carbs, it really helps fixing the butcher jobs by the "carb experts".

I saw a post where Holley was getting off of their 660 cfm #4224 carbs.

Many years ago that was a popular carb for the Small Block Chevy Racers when used with a Tunnel Ram. The carbs could be modified by a Drag Racer like Paul Bevins (RIP) to where they worked pretty well on the old mid 10 second drag cars in the 1972-1973 time frame on the strip.

Here is a link to a Super Chevy article from the 1973 days.

http://forums.superchevy.com/chevy-h...-paul-blevins/

John Dianna wrote the article. Excuse the title where they call the carbs #4334 Holley carbs vs the correct number #4224 carbs.
They get the later text right though. Someone did not proof read the article apparently.

So the article is about Paul's Corvette 327 cid Race Car with the Tunnel Ram and the Holley carbs along with the mods he does.

1) Paul modifies the Cam and Slot actuated linkage by increasing the delay of the secondary openings so that the engine is basically launching on one "carb" (composed of the Primary barrels on the first carb and the Primary barrels on the second carb).
Basically he is delaying the Secondary Blade Openings until the Primaries are half open vs just off idle in a stock Holley #4224 built configuration.

Then the "delayed linkage" opens up the rear barrels on the two carbs.
So the carbs are basically changed from a "Idle Position/ WOT Carb Position" to a lower horsepower "Combined Carb" situation to a combined dual quad WOT situation.

Paul also delays the Pump shots on the center squirter carbs until much later and also modifies the cam position on the cam levers.

Paul restricts the Idle Feed Restrictions using fine wire.

He keeps the 4 shooter nozzles the same as stock (.025") per nozzle.

(ALL OF THE MODS ARE EXPLAINED IN THE ARTICLE)

A lot of OLD SCHOOL Holley Carb Tuning as in those days you did not have access to the Metering Blocks out there today and the ability of change orifices easily.
Plus the carb knowledge is much higher today.

So the people who will buy the carbs will get some new Holley 660 cfm carbs but the reality is the #4779 750 cfm double pumpers are a lot better Tunnel Ram or M/T Cross Ram Dual Quad carbs with the right modifications.

Tom V.

Tom thanks I actually remember that article! The blending of the throttle bores and delaying throttle linkage. My old memory knew it was a SB Vega but thought it was Grumpy Jenkins'.

The pictures I posted previously were Photobucket copies and of poor quality.
Here are some better pictures of the article.

Tom V.

The better pictures of the Hot Rod Article can be found on a website called Grumpys Garage.
You have to sign up though to actually read the info. Lots of good info on that site.

Rather than have the PY Members sign-up on Grumpy's Website, I will post up the Information/Pictures over several posts. Believe I can post up to 5 Pictures at a time.
So here are Pictures #1 thru #5

In the 1st Picture if you look closely you can see the Center Squirter under the Air Cleaner Bale.

In the second Picture you can see the Cam/slot linkage used to open the secondaries.
There is a very small amount of travel before the secondaries are starting to open.

In the Third Picture you can see the opposite side of the carb.
You can see the square plug in the metering block where the Ported Spark Nipple would go. (Hose from nipple to the Vacuum Can nipple).

In the Fourth Picture you will see a better view of how short the primary blade travel is before the secondary blades will begin to open.

The last picture (in this group of 5) shows two important things:

1) Never put the Phillips Head Screws in the two center locations of the throttle Blade base WITHOUT a plate under the screws (that can keep the center screws from falling into the intake at exactly the wrong time. The carb will seal fine without them being installed.

2) The slotted passage connecting the rear carb barrels is a great area to provide by-pass air (and keep the Primary blade position perfect in relation to the Transfer Slots).
What you do is remove the "Flat Blade Screwdriver Plug" on the baseplate and thread in a aluminum plug that has a orifice that allows the idle rpm you want. Basically does exactly the same asm the Barry Grant IDLE-EZE system or the Holley Idle Air Bleed system on some of the HP and Ultra carbs. Buy the plug, start with a small .062 hole drilling and then increase the hole size until you get the idle speed you want the engine to idle at. Different engine, drill a different plug for that engine. You can do the bleed on both carbs and make the flow area 1/2 the size if you want bleed air coming into both carbs, like on a MT Cross Ram.

Tom V.

Picture #6 shows several things:
a) The carb base does not have the fuel bowl "stale gas purge passages" milled into the base like a typical Holley #1850 carb or #3310 Vacuum carb has. The assumption is that the secondaries would get used constantly with the small distance before the secondaries would be at least partially passing fuel thru the metering plate.

b) The 50cc/ten stroke Accelerator Pump Arm is visible.

c) The roller for the secondary lever is easily seen engaged in the primary linkage cam slot.

d) The Transfer Slot Millings are easily seen for the Front and rear circuits.

In Picture #7 you can see the bottom of the baseplate clearly. Again never install base screws in the two indented middle positions. (Unless you have a steel plate directly under them. Even then be careful if you install them. Sometimes bad things happen.

In Picture #8 you see the typical Mainbody to Base carb gasket.

In Picture #9 you see:
a) the Factory Choke Tower and the milled slot to install the 4 shooter squirter (where the normal carb stud would normally be.
b) The shooters for the rear barrels are easily seen.
c) You can see the normal Accelerator Pump Shooter location capped, (the carb has a drilling that goes past the primary shooter and goes into the boss drilling normally used by the air cleaner stud.
d)The "Straight Leg Boosters" are apparent.

In Picture #10 you can see that the Rear Blades have the Transfer Slots covered.

Tom V.

More Pictures and #4224 Carb info tomorrow.

Good Morning, More on the Holley #4224 Center Squirter Carbs

Picture #11 shows a nice example of the "Square Window" that many say is ideal for the Transfer Slot vs Throttle Blade Position on the Holley Primary Side of the carb.

Picture #12 shows the Secondary side of the carb Air Horn area. It also shows that the Air Bleeds are fairly close in size.
Typically the Idle Air Bleeds here are a few thousands of a inch larger vs the High Speed Bleeds which many times are .025" in diameter.

Picture #13 Shows the Primary Side of the carb.
You can see that the Idle Air Bleeds (ones on the outside positions are larger -typically in the .070" range) vs the High Speed Air Bleeds (in the .028" range).

Picture #14 Shows the Accelerator Pump Cam for the Carb which used the 50cc (per 10 strokes) Pump and Diaphragm.
The Pump Arm is visible, the cam, and the Idle Set Screw are shown.

Picture #15 shows The Secondary Blade Position Screw (which keeps the Throttle Blade from "digging into" the Carb Base Plate.
It also shows that the the adjustment for the Blade location must be done with the carb removed as the Hex Opening for the allen screw is on the bottom of the carb. Some move that hex opening to the Top of the Throttle Base but if you use the Idle Eze type drilling in the Plug (right next to the screw) there is no need to ever move the screw.

I drill the Plug for a .060" opening initially and then increase the size slightly until I get the idle rpm I want. Most times you will have two carbs so you can start at .045" drilling and then go up by .010" using a precision drill set to get the right idle speed.
Do not touch the normal idle set screw once you have the Primary Blade position set for the Transfer Slot "Window" opening.

More pictures later today or tomorrow.

Tom V.

More Pictures:

Picture #16 You can see how little Primary Shaft Travel there is before the Cam Slot touches the Roller.
As was Posted earlier in the Paul Bevins article, you can grind away the slot hump so that the roller does not contact the cam until about 1/2 way up the slot, the Secondaries will still open completely with the delayed secondary opening.

Picture #17 This picture is again the Primary Metering Block mounting surface on the Carb Main Body.
On New Carbs this will be flat and have a Dichromate finish that protects the Zinc material that the carb components are made of:
MainBody, Metering Blocks, and Fuel Bowls. If we were talking about other carbs the parts might be partially made out of aluminum.
In this #4224 carb case only the Throttle Blade Base is made from Aluminum.

Picture #18 This is a picture of the Primary Metering Block.
It has the typical TWO Drilled Emulsion Holes on each Primary Carb Bore Circuit, which has worked very well for performance carbs for many years. It has the two Kill Bleed Holes located in the TOP POSITION of the Main Channel of the Metering Block.
It has a Cast In (Non Drilled or Machined Power Valve Metering Block.
The Square Head Plug sealing off the Spark Port Channel is obvious but also the top of that channel has been drilled so that if a person wanted to use Spark Port vs manifold Vacuum to control the Distributor Vacuum Advance it would be possible.

Picture #19 Shows the Number "12" Metering Plate which has a .031" Idle Feed Restriction drilling and a .076" Secondary Main Metering Restriction drilling. A Holley .076" Orifice is roughly the same as a #71 Main Metering Jet.
If you converted the carbs to a cross mount position (like on a Tunnel Ram intake and used a Replacement Rear Metering Block Kit (Part Number 34-6) you would get the Metering Block, longer Bowl Screws, a longer Secondary Fuel Feed Tube, two 'o-rings" and the metering Block gaskets. NOW you could install your #71 Metering Jets in the Rear Position.

Picture #20 is a simple intermediate sealing plate that goes between the Carb Main Body gasket and the gasket that seals the plate to the Rear #12 Metering Plate casting.

Tom V.

More Pics and info:

Picture #21 shows the other side of the Metering Plate with the machined passages clearly shown. The Idle Feed Restrictions are shown in the top left and top right corners of the plate. The Emulsion passages are in the center part of the plate and the "jet" drillings are in the center at the bottom of the plate.

Picture # 22 shows the Fuel Bowl Side of the Primary Metering Block. The Jets are clearly visible. The Vent Whistle is the Plastic piece at the top and the metering Block obviously has no Power Valve circuit.

Picture #23 shows the REAR Side Hund Float Bowl.
You can easily tell that because the Transfer Tube Fuel Boss is on the right side of the picture and the "Sight Plug" for checking the fuel level in the bowl is on the left side.

If you had X-ray vision you would be looking at the carb from the front of the engine.
You typically set the Fuel Bowl "Float" to where the Top of the float is basically horizontal to the top of the bowl first and then readjust once the carb is installed on the engine and fuel has been run thru the carb to the bowl.

Picture #24 shows the Plastic Fuel baffle that surrounds the Needle and Seat assy inside the carb.

Picture #25 shows the Primary Fuel Bowl (fuel inlet nipple is on the left top side.
The small spring on the bottom of the float dampens out vehicle vibrations in the fuel bowl. The accelerator Pump (50cc per 10 strokes) is clearly shown attached to the bottom of the bowl.

When the pump is activated the fuel comes out the small hole in the fuel bowl.
(The small hole above the Accelerator Pump.)

Tom V.

I will discuss Pictures #26, #26, and #28 tomorrow but have attached them to this post.

Good Morning.
The first Picture (Picture #26) is an old Holley Carburetor Magazine Ad showing the 3 Carbs designed for Performance in the 60s. The #4224 Holley Center Squirter, the Holley 3-BBL (Vacuum Secondary) carb, and the 350 & 500 CFM 2-BBL carbs: #7448 & #4412.
That series of Carbs has had a long history of Racing Success in many different types of competition.

Picture # 27 (sorry for the typo above), shows all of the drillings on the secondary side of the typical Vacuum Secondary (metering plate) carburetor.
The Threaded Holes attach the Metering Plate to the mainbody and the plain drilled holes are the Fuel and Air passages for the carbs operation. The spots with the black marks next to them are the Alignment/Attachment Holes.

Picture # 28 is your typical Dominator Replacement Fuel Bowl Set.
This allows you to put the fuel into either side of the fuel bowl.
It also allows you to have new bowls if you have a good used mainbody and metering blocks.
The kits can be had with the "Sight Plugs", the Bowl Screw Washers, the Bowl Gaskets etc. The accelerator Pump, the Fuel Nuts (to block the opposite side opening, and the other parts like the Needles and Seats are all extra cost items in the catalog.

Tom V.

The #4224 carbs are still out there.
I have a few of the old #3160 carbs (3-BBL) in 950 and 1050 cfm (4 bbl ratings) but the parts for them are long gone.

The Old #4412 500 cfm 2-bbls are common, the old #6425 (650 cfm) 2-bbl circle track carb and the #4782 and #4782 Mechanical Secondary 2-bbl race carbs are occasionally seen on e*ay.

I want to post up a couple of additional pics, not related to the #4224 Carbs specifically but for good information.

Attached is a baseplate picture from a website compant on E*ay that carries a large amount of individual Holley carb/Quickfuel carb type replacement parts that you would use when rebuilding your carbs.

https://picclick.com/eBay-Motors/Par...buretor-Parts/

I have my own sources for Holley Carb Parts but it might help other PY Members who are looking for specific pieces to redo a carb that they have.

Not a ADvert, just a link to some great pictures of Holley parts.

Tom V.

It has been a while since I posted in the Holley Carb Tip Thread.

I will post a few pictures today.

Then I will describe what each picture is showing us.

1) In the first picture , the pointer is showing the "Adjustable Emulsion Jets installed in a Special Holley Circle Track Metering Block.

2) Second Picture shows a neat little jet that is actually a "Kill Bleed" for the Accelerator Pump Circuit to keep fuel from being drawn
out of the shooter at high speed and screwing up the air/fuel mixture you worked so hard to get at max power levels.

3) Third Picture pointed is showing the LOW POSITION Idle Feed Restriction (this position works very well for many carbs).

4) Fourth Picture shows the later style High Position Idle Feed Restriction (This position supplies air and fuel to the idle circuit and
many times causes a tuning issue with the carbs. Many Knowing Tuners move the IFR back down to the low position and the
tuning issues go away.

5) Fifth picture shows the Adjustable Power Valve Channel Restrictions. For max power conditions you tune with the PVCRs and not
with the Main Jets. Some do not know how to do this so they just remove the PVCRS, install PVCR "plugs" and try to tune the carbs that way. It might work ok on a 1/4 mile car but on a track car or a street/strip car, using the Power Valves and the PVCRs is the way to go.

Tom V.

ps the older holley carbs did not have these features because of two reasons: "One" the extra machining cost money and "Two"
Holley wanted to sell more carbs vs allowing a tuning capability by the average enthusiast. Today the Enthusiast with a Air/Fuel
meter can get close to what the Holley Engineers used to do with calibration changes. Today you spend a few hundred for the meter and
UEGO sensor, in the old days (60s) Holley would spend thousands for a professional Lamda meter.

Now at the top of page 7 of the blog, likely it will continue to move as content is added, but still be available.

Invaluable wealth of information you have compiled here Tom, I have a bit of catching up to do.

More than likely a few questions as well.


Thanks,
:popcorn:
Frank