#441  
Old 01-20-2020, 12:48 AM
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A post from the Chevrolet Board answers that question.

"Anyone have any experience with some Frankenstein creation like this?

My friend just bought some parts, one of them being a 4779 Holley (700 DP, don't know the -number), 4150, dual metering blocks Prim #11173 and Secondary #11166...

But the bowls have been changed from the center-hung floats to the single feed, banjo bolt fitting, adjustible float bowls. It has two primary bowls, because its still has the "secondary" accelerator pump. Looks like the fuel transfer tube holes have been plugged (another sign that it is using a primary bowl on the secondary side), and it has a "T" in the fuel line, so both bowls use their own hose/banjo fitting for the fuel line.

Not sure exactly why it was done, but I suspect it was to gain clearance in the carb enclosure, although I have seen regular Dual Feed DPs fit...

The carb fits inside a enclosure for a '66 Shelby Mustang Paxton supercharger setup setup...

I can see the DP linkage, the base plate has the second pivot stud and lever, the main body has the secondary squirter..."

More Clearance for some Bonnets or enclosures like the Vortech or Paxton Carb Box,
but most likely for the earlier Shelby/Paxton Box.

Tom V.
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  #442  
Old 06-28-2020, 08:29 PM
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Here is a link to carb numbers I provided to a member in the street section.


His carb was R80777 4150 carb 650 cfm

The info on Holley carbs can be found here:

https://documents.holley.com/techlib...al_listing.pdf

About 12 pages down the document.

Tom V.

Now everyone will know where to look.

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  #443  
Old 07-06-2020, 10:13 AM
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Today I will post a bit about Center Squirter Holley Carbs.
Many people are aware of the 660 cfm #4224 Holley carbs with the center squirter
design and the 1-3/8" Venturis and 1-11/16" throttle blades.
These carbs were used on hundreds of Chevrolet SB Chevy Drag Race engines.
AND a few Pontiac Engines like Richard Burnhart's GTO.

The 850 CFM #4223 center squirter carbs had exactly the same design but had the normal 850 cfm carb venturis and the slightly larger 1-3/4" throttle blades.

These were the LARGEST MECHANICAL SECONDARY (NON DOMINATOR) RACE CARBS OFFERED IN THE EARLY DAYS. i have provided some pictures below showing the features of the carb.

Tom Vaught

ps my computer had a computer glitch and would not allow me to post pics or excel file info for a few days so the Tri-Power info for 1965 and 1964 has been on hold.
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  #444  
Old 07-06-2020, 12:59 PM
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You may have covered this, but I purchased a matched pair of 660 center squirts in the early '80's for a Weiand 440 2x4 tunnel ram I was fabricating for use on my 409CI Chevy.

The guy who sold them to me pointed out the the carbs used a bigger 750? base and the base was matched to the carb using a taper boring bit to give the smooth transition. They were professionally done and I got them for a song back then.

  #445  
Old 07-06-2020, 02:07 PM
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He really did not do much to the carbs as STOCK, (per the Holley Specification Manual)
1-1/4" Primary Venturis, and 1-5/16" Secondary Venturis, and the Normal 1-11/16"
Throttle Plates in all 4 spots.

He might have pointed out the "750 base plates" but those base plates were all all 650 to 800 cfm Double Pumper Carbs and and also just about every 750/780 cfm Holley carb. A couple of oddball Ford Carbs used a different baseplate and different sized throttle plates.

So a lot of smoke and mirrors but not much different from a stock 660 carb (if at all different). The mechanical opening linkage and the center squirter 4 tip nozzle is the main difference along with the 50cc (5cc per stroke) accelerator pump.

Tom V

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  #446  
Old 07-06-2020, 02:49 PM
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I had forgotten about this thread until Tom started posting in it again. Lots of great information here, Thank you very much Tom for posting all of it. After going through all 444 posts and pulling out all of Toms' info; I now have a 230 pg word document. Tom you did a lot of typing for sure, Thank you so much for your efforts.

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  #447  
Old 07-06-2020, 05:47 PM
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Thanks Very Much. Glad to pass on the info.
Several people have told me I should write a book.
One reason why I started this thread was to pass on Holley Info
so people did NOT HAVE TO BUY A BOOK, LOL!
No need for that deal as Mike Urich (my old boss) already wrote those books years ago.
Mike Urich was Manager, Holley Aftermarket Engineering when I knew him.
Chuck Gulledge was one of his best Holley Engineers, very sharp. Later a top Pro Stock
carb builder after he left Holley.

Mike Urich was later a Vice President of Engineering at Holley Carburetors.

Read his stuff first and then later blend in some of my posts with that info.

Tom Vaught

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Last edited by Tom Vaught; 07-06-2020 at 06:40 PM.
  #448  
Old 03-28-2021, 06:11 PM
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WOW, Last post on Holley Carb information was by me was July 06, 2020.

Time to add a few pieces of information/history. Specifically on a very special Holley Carb designed by Holley Engineering for the 1966 Le Mans 427 single 4 BBL GT-40 Engine. This carb was the very first Center Squirter
Carb and the first carb with the unique "Nose Fuel Bowls" and with full mechanical secondary activation vs Vacuum secondary activation. Other carbs might have one or more of the above but not all of them.

I will also post some pictures of the unique parts of the carburetor.

So Picture #1 is a throttle linkage side of the carb with the "Nose" Bowls.

Picture #2 is another carb/ engine picture showing the right side of the engine and the special headers for the engine.

Picture #3 is the top view of the carb in the Ram Air Enclosure. You can see it is a Center Squirter Carb and has almost immediate secondary opening on the 780 cfm carb. A very Rare Carb used by Ken Miles who wanted full mechanical control of the throttle operation. Holley later updated the carb to a 850 cfm center squirter model.

Picture #4 is a close up view of the carb. These carbs were later used as Tunnel Ram carbs.

Last picture for today, here you can see the Holley "center squirter" carb on the 427 engine in Ken Miles Ford GT-40
race car. (car #1)

Tom V.
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  #449  
Old 04-03-2021, 10:52 AM
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Quote:
Originally Posted by Tom Vaught View Post
WOW, Last post on Holley Carb information by me was July 06, 2020.
Last picture for today, here you can see the Holley "center squirter" carb on the 427 engine in Ken Miles Ford GT-40
race car. (car #1)



Tom V.
In a bit of respect and history, what a shame about Ken Miles in the 1966 24 Hours of Le Mans, all because someone wants some publicity, very unfortunate.
Then to loose his life and never get another shot. Sometimes you get the short end of the stick, sometimes you don't even get a stick.


On a better note, glad your back from vacation Tom, been missing school and could always use some education. Love the 780's but never seen one of those.

I always thought 780's were awesome carbs right out of the box, and my go to carb for Pontiac and Olds 400's, always worked very well for me.

Question is, how many revisions or versions of the 780 has there been, not including factory equipment units, just over the counter type?

Please try to be explicit as to what point it was they turned to chit, i.e. the higher IFR location and move from Zinc metering blocks to the Aluminum stuff.

I imagine this info could be useful to myself and others as it most likely pertains to most historical era Holley's as apposed to the newer type units.

Pic of metering block showing improper higher IFR location, from the 12-26-2017, 09:10 AM post in this thread.

Zinc to Aluminum material info from this thread https://forums.maxperformanceinc.com...d.php?t=849490.





As Always, Much Thanks!

Frank

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  #450  
Old 04-03-2021, 12:41 PM
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Tom..I've thanked you before for help..but I'd like you again for this thread..keep it going..great thread!

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  #451  
Old 04-03-2021, 01:40 PM
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Quote:
Originally Posted by ta man View Post
Tom..I've thanked you before for help..but I'd like you again for this thread..keep it going..great thread!
Appreciate ^ TA, I oouldn't say it better. Thank you Tom,please keep school going for us, your efforts are very much appreciated!

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  #452  
Old 04-03-2021, 04:56 PM
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An effort to consolidate and means to navigate, this bit of info is pulled from the 05-18-2019, 10:05 AM post of this thread and pertains to the best location for the IFR.

Quote:
Originally Posted by Tom Vaught View Post
The best location for the IFR (Idle Feed Restriction) was identified in carburetors and the results reported in NACA REPORT #49 (Part II on page 607) See link below.

http://naca.central.cranfield.ac.uk/...-report-49.pdf

In the conclusions part of the document, conclusion #4 clearly states that:

"Submerged Fuel Metering Passages (IFRs) are free from Instability and Irregularity of discharge when the head is very small."

You can not have a submerged Fuel Metering Passage when the IFR is in the "HIGH" Position, (only the "LOW Position").

There are 10 other conclusions and all of them are correct.

Many Carb Tuners have converted back to the Low Position IFRs even though the Holley Carb came stock with the High Position IFRs.

Hope this helps.


Tom V.

Again, Much Thanks Tom,

Frank

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  #453  
Old 04-03-2021, 09:14 PM
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I believe that link no linger works but here is a attempt to post the info in a screen shot, (looks like it worked).

Look at point #4

Tom V.
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  #454  
Old 04-04-2021, 10:08 AM
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Quote:
Originally Posted by Tom Vaught View Post
I believe that link no linger works but here is a attempt to post the info in a screen shot, (looks like it worked).

Look at point #4



Tom V.
Appreciate that, it's been broke, didn't know if it was me, at times I have issues loading pages.

Sometimes I wonder if there's a conscious effort to subvert info in a attempt to prosper from it.

One of the very reasons I'm grateful for all the info provided freely by everyone on the forum.



Thanks'

Frank

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  #455  
Old 06-12-2021, 02:55 PM
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Been a while since I posted on the Holley Carb Sticky.

I was looking at some Hot Rod Magazines I plan to donate to a retired Holley Guy I worked with back in the 1970s. He is putting together a "Library" of information that was printed in all of the old paper magazines, like Car Craft, Popular Hot-Rodding, Hot Rod, etc. I have donated to him about 6 thousand magazines so far. Still have a lot to deliver to him at a later time.

So I ran across a Hot Rod Magazine dated Hot Rod 2013 JULY and I will talk about an article called "The Holley 6 Pack Carbs, on Jim Mooneyhan's '70 Dodge Coronet, 440 are messed up. We are going to fix them.

So without typing the entire article, I will post the Issues that Mr Mooneyhan has with his 6-Pack set-up:

1) The car (engine) idles too fast.
2) The Throttle Response is bad.
3) There is a lean surge at 55 mph.
4) The engine seems rich at idle.
5) Turning the Idle Mixture Screws or Idle Speed (Throttle Blade) Screw has no effect.

Info: The End Carbs are original 440 6 Pack carbs. The Center Carb, He said, was correct for a 440 Six Pack set-up with auto trans. This info is from Marlin Davis, a Hot Rod writer. So they took the car to "Joe's Garage", a shop in California apparently.

It was delivered on a trailer to the shop and when attempting to get it off the trailer it had a 4000-5000 rpm "idle".

Initial Diagnosis showed the following issues, as received:

a) A bent "Divorced Choke" linkage. Choke was not completely allowing Curb Idle speeds.

b) Center Carb had a "Blown Power Valve" Normally this would not be an issue at idle but at 4000 - 5000 engine rpm would be adding fuel to the engine increasing the speed.

c) Center Carbs intake manifold gasket was damaged (leaking), allowing increased idle air into the intake.

d) Center Carb had 90 main jets on the center carb (normally used on only the rear of 4 BBL carbs unless you are racing a Dominator Carb). 6 Pack rear carbs use Metering Plates vs Metering Blocks.

e) A 50cc Accelerator Pump was installed on the Center Carb. In some cases on 850 cfm #4781 carbs for racing this mod works with the large cfm primary barrels. NOT on a small center carb on a 6 Pack set-up (which was later identified as a 340 6 Pack carb, not a 440 center 6 Pack carb).

f) "An Idle Air Bleed on a "end carb" was blocked".
Just for information for the guy who was given the info about the carbs, THE INNER AIR BLEEDS ARE THE HIGH SPEED AIR BLEEDS. THE IDLE AIR BLEEDS ARE THE ONES CLOSEST TO THE OUTSIDE OF THE AIR HORN RING. The blocked air bleed was a high speed air bleed.

g) The End Carbs had "sticky" throttle blades. Not opening and closing smoothly most likely caused by the other issues and a lack of maint by the owner.

h) Two bad plug wires and fouled spark plugs.

i) Idle vacuum at best was 5" of idle vacuum but the engine was pumped and found to be solid internally.

Fixes: Basically fixed all of the issues mentioned above, converted the Holley center carb to a 440 center carb calibration. Not sure what the Holley people told them to do vs just replacing the carb with a proper 1970 Holley 440 center carb which Summit/Holley was selling at the time. I would have put the right center carb on the vehicle immediately. Today 2021 that may not be as easy to do, back then they were available.

(I fixed a Ford Guys Holley Tri-Power Set-up one time (for free) after the guy had a shop Powder Coat the carbs vs (have them dipped properly) and "unplugged" most of the air bleeds in those carbs, along with putting the right calibration in the carbs.)

SO THE POINT OF THIS IS, TAKE YOUR HOLLEY CARBS TO A SHOP THAT ACTUALLY KNOWS HOW TO WORK ON THEM PROPERLY. Especially if they are rare set-ups.

Tom V.

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  #456  
Old 06-27-2021, 11:19 AM
64gp4spd 64gp4spd is offline
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Tom, Great Thread I have a question regarding idle mixture screw adjustment.
I have a Holley HP950 Street carb on a Torker 2 intake, with 1 inch spacer
Engine is 463, Kauffman Heads, 11:1 compression. around 12-13 inches of
vacuum at idle. It seems to run and idle really well, but
I am not getting much adjustment out of the 4 corner
idle mixture screws.
I noticed through the sight glass that the fuel levels
front and back were high so I lowered the float levels to where the fuel level
in the center of the sight glass. I did see in this post that the throttle blades
may need to be readjusted. Can you tell me what the process is to re-adjust
the blades?

Thanks, Rich

  #457  
Old 06-27-2021, 12:15 PM
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Most Holley 750 cfm 4779-1, 4779-2 thru 4779-5 were TWO Corner Idle carbs.

Same deal for the Holley 4781 850 cfm early carbs.

The carbs did have a pair of tiny fuel discharge holes under the transfer slots on the secondary side of the carb to let a bit of fuel get purged from the secondary fuel bowls if the owner was not opening the rear throttle blades constantly.

So then about Holley 750 4779-6 Holley added the 4 corner idle circuits to allow using a common metering block on the front and the rear of the carb to make more fuel flow thru the rear idle circuits of the carbs.

The OLD setting on a carb for the primary 2 corner idle mixture screws was 1 and 1/2 turns out from seated. The 4 corner carbs spec was 3/4 turn to 1 turn out for those carbs. Supposedly this helped the fuel distribution in open plenum Holley Intakes. The total idle fuel supplied to the engine was the same in both carbs.

The only Throttle Blade adjustment is to set the Front Primary Blades so that you have a square window when you look at the carb from the bottom and the Primary Transfer Slot. Then you never touch that idle speed screw on the base plate again.

The secondary blades need a slight modification. You make sure the blades are centered in the bores when closed and then you flip the secondary throttle blade "stop screw" so
that you can adjust it from the top. Screw Driver "slot" now goes on top (pointing at the sky) and you can adjust the secondary blade position to get the best idle rpm for your engine. Most times you can leave that screw alone too. So from now on THAT SCREW is what sets your Idle RPM.

Hope this helps.

Tom V.

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  #458  
Old 06-27-2021, 12:30 PM
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Thank You Tom, really appreciate it

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Old 06-27-2021, 02:34 PM
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I've used the the rear for setting idle for a few years. I still get the odd funny look from guys when I'm changing my idle at the track using the rear. Both my carbs are set up with a nice knurled screw that I can easily reach and adjust.
Thanks for all the tips over the years.

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  #460  
Old 06-27-2021, 08:06 PM
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Glad to help and this way the carb can operate with a fixed calibration at idle, and off idle basically the same (day after day) and you never "Lose the Rabbit" (constantly playing with a group of circuits) that rarely need to be changed for low speed operation.

Tom V.

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