Some here might find this Holley history interesting.

[HarrysTaxi2]

https://www.youtube.com/watch?v=JW21G0o1bdk

[GTO Geoff]

Interesting. About 1hr 30 min in, he talks about the vac sec carbs having better ETs than d/pumpers.

[Right hand drive]

Thanks for sharing HarrysTaxi2.

Awesome information and so much I’ll have to have a second viewing.

Opening up main well, angle channels and booster leg due to size creating too much wall friction was one highlight and something he was absolutely adamant on. Also the reasons AFB, TQ, Quaddies will never make the same power as the ‘plain tube’ Holley - density to the cylinder. There was heaps more good info that will take more viewing taking notes. The story involving Braswell was good.

I’ve subscribed in the hope he will return and talk tuning as he stated he wants too.

[rgalajda]

That was a great interview listening to one of Holley’s old employees , before the changes took place.
Smart guy for sure.

He was a little off on Quadrajet main well plugs. In the early quadrajets these plugs were brass which did tend to leak with time. Later units made after about 1968 used pressed in aluminum plugs and swage sealed. The method continued to improve. It is quite rare to find 1975 and later quadrajets to leak. Covering them with epoxy is a temporary repair not permanent as it only peels off with time.
There is a permanent repair for these.
There were no steel plugs or o-rings like he stated.

Some things have to be put into “context”

David Vizard talked about the Holley vacuum secondary carbs ( properly tuned ) as opposed to the (mechanical) double pumpers for street and street/strip cars. It is mainly about torque output below about 3-3500 rpm. ( Good point Geoff )

I believe he said in the video opening main wells on all holley carbs. Not sure this is what he meant. I wouldn’t go grab your drill and start ruining innocent carbs. Tuner spoke about this years ago, on I believe early 3 circuit Holleys.

“Also the reasons AFB, TQ, Quaddies will never make the same power as the ‘plain tube’ Holley - density to the cylinder. “
He states you just can’t make horsepower with a Quadrajet.
At what power level is he talking about? It is easy to drop a word like density and no one knows what he is talking about. I believe some of the Super Stock racers had to run Quadrajets and look how well they do. He was definitely a little Holley biased.
Also he states Quadrajets being rated at 725cfm. Quadrajets can be divided into two categories,
750 cfm and 800 cfm ( capable ). Because they were used on everything from a 427 BBC and Ram Air Pontiacs to 305 cu. in. And V6 engines the secondary air valve was set to a fixed opening when produced and non adjustable. So they actually ranged from approximately 500 cfm to 800 cfm depending on application . All of them can be tuned to full cfm if you manipulate
the air valve opening.

When he talked about engine cooling temperature running 220 degrees to 250 degrees for road racers to make optimum power . ????

The holley 3310-1 was the first aftermarket 3310 with the distribution tabs. He spoke of the 3310-2 correcting ( Deleting ) the distribution tabs. I believe the 3310-2 was a move to make more profit on a highly successful selling carb. The dogleg booster was replaced with a straight leg booster and the rear metering block was replaced with a metering plate. Later versions lost the slash cut brass tube in the primary bore for the secondary vacuum diaphragm. You can see where this is going. It was not just about removing ( rightly so ) the distribution tabs.

He did mention emulsion ( on the old Holley’s ) was mostly right.

[GTO Geoff]

Yes, agree a little bit of Holley bias there & the nonsense about 'density' & AFB Carters not making as much power as brand H. Edel compared a 6619 Holley to a 600 AFB on a 350 Chev & the AFB made 17 hp more, 17 ft/lbs more tq & used less fuel doing it. Before anyone says Edel was biased, it was looooong before Edel started making the AFBs & in fact they were selling modified Holleys under an Edel part #!!
The late Joe Sherman used only AFBs on his engines which were very competitive.

Tom Vaught, a degreed engineer, spent many years working for Holley in the glory years. Cliff Ruggles, author of the QJ book, posts on the Performance Years, as does Tom. Tom prepared an 850 H for Cliff to compare to one of Cliff's QJs & it was no better at the strip [ 11 sec car ].

[GTO Geoff]

I watched this video again. First time I only watched sections of it. While there was some very interesting history & tech, there was also a fair amount of nonsense & BS.
- the claim that the Pontiac HSD intake makes 43 hp more than the Edel Torker. From personal experience. When I built my first 455 Pontiac in 2001, I used the HSD because they ran well on BB Chryslers I had been running. Very disappointing, dead down low. Where was this legendary low end tq of the 455 I had heard about?? So off came the HSD & on went a Perf. The very first time I did a WOT run & changed into 2nd gear, I blew the 2nd gear sprag in the T 350. In the H book, there are a few HSD intakes, with a 4bbl, tested against factory 2bbl intakes & the hp increases were in the 30-40 range. Hard to believe that that the single plane HSD was 43 hp better than the single plane Torker. A more scientific test: Pontiac guru & racer Jim Hand wrote a book on building Pontiac engines. He tested the popular intakes at the track with his consistent LeMans waggon that was running 12.5 -12.75 at the time. T400, auto shifted, at 5200. The Torker ran 0.04 sec slower than the HSD. Given the T was rated at 3500-7000rpm, a higher test rpm would likely have yielded closer or equal times. Sorry, I don't see 43 hp there...
- this one also surprised me: the claim that AFBs do not have sec venturiis. They sure do!!
- and the density nonsense & the Holley carburetor is a 'tube carb'. What carb with round throttle bores isn't a tube carb??? Went on to try a claim that air valve carbs were 'restrictions'. Not at WOT! In fact depending on engine capacity, well before WOT. Mark must have forgotten that Holleys have shafts, t/blades, just like other brands. And I think he forgot that AV carbs do not have a sec venturi & booster blob to impede flow; Holley carbs DO have sec venturiis & boosters to impede flow. At WOT where max flow is reqd, an AV carb just has a thin blade & dump tubes. I am surprised he did not read page 8 of the book his Holley boss, Mike Urich wrote about CFM rating & density.
- Xerox copy machines weigh 4000lb? That is 2 ton. None that I saw in servicing copying machines over 20+ yrs.
- Really low rent to call Jim McFarland 'stupid'. He was/is well respected inside the industry. Edel had a really successful period while he was VP there. Edel was first in the industry with many concepts, such as the single plane manifold [ Tarantula ] .... which others copied...including Holley. Holley might have improved on it , but credit should be given where due.

[Right hand drive]

I agree he would have bias toward Holley, being someone that has connection to their design.

As to the density, it’s the mass of air/fuel an engine sees and needs more of to increase power. Because an engine has volume and air/fuel mass is being induced then you have a density of air/fuel (density = mass/volume). I’ll let a Mike Urich & Bill Fisher quote from Holley Carburetors & Manifolds help explain:

”Many people believe the throttle controls the volumeof fuel/air mixture being pumped into an engine. This is not the case. Piston displacement never changes, so the volume of air pulled into the engineis constant for any given speed. The throttle controls the density or mass flow of the air pumped into the engine by the action of the pistons: Least density of charge is available at idle, highest density at wide-open throttle. A dense charge has more air mass, hence higher compression and burning pressures can be developed for higher power out-put. Thus, the throttle controls engine speed and power output by varying the charge density supplied to the engine.”

Mr Campbell was saying that ultimately the air-valve style carburetors cannot supply as much air/fuel mass as the plain tube carburetor due to the air valve design/function. That’s how I heard it anyway. I wouldn’t think he was talking of 11 sec quarter mile level or of those test you refer to Geoff, but of a higher hp level.

I took all of what he was talking about from a high performance perspective. So when it comes to drilling of the main wells etc I wouldn’t contemplate it if my tuning goals were efficiency and emissions as it would be pointless. But looking for a performance advantage it may be worth the trial to get some old blocks and do a before and after test. What he was referring to is that due to a liquids propensity to adhere to a solid (fuel to well wall) it is too hard to get the smaller volume of fuel of the standard diameter main well moving quickly so enlarging the well allows more fuel away from the wall to get moving quicker. Remember he said a main jet change would be in order to balance pressure differentials. Larew speaks of this wall adherence in Carburetors & Carburetion:

”The surface tension of gasoline and the adhesion of gasoline to the surface of a nozzle cause the gasoline to tend to stay in the nozzle”

And

”Assume also that the air bleed orifice is closed. Then the head tending to cause a fuel flow through the nozzle may be such that the fuel flows in a series of large drops from the nozzle because of the surface tension and fuel-to-nozzle adhesion above, or perhaps does not flow even though it is above the bottom of the nozzle opening.”

So I took the reasoning by Mr Campbell for opening up the main well to .180” to improve fuel flow between lowest active emulsion bleed and main jet. Opening angle channel and booster leg to .166” may perform a similar function or required to support extra fuel.

Geoff, check out the below link. Under ‘How Edelbrock Created its Nearest Competitor’ it’s mentioned that Edelbrock were working with Carter as early as ‘73/‘74 with the AFB. There was reason for them to start favoring the AFB.

https://www.motortrend.com/news/hrdp-13 ... edelbrock/

[Right hand drive]

[GTO Geoff]

RHD,
Edel made manifolds for engines that originally used Carter Carbs. Why wouldn't they use CC for testing? If they were 'looking' at Carter in 1974, then they changed their mind because my 1979 E catolog contains nine Holley carbs along with a heap of H parts. Part # 4388 is a 0.093" bush for use re-calibration for idle feeds, MAB, Int AB etc. They are not listed in my 1984 catalog, so dropped over that 10 yr period. If you want a copy, pm me your email address.

[GTO Geoff]

RHD,
Correct on the Holley book quote. Further down the page it states in italics that the other end of the curve is the limiting factor. Essentially saying any dope can make a huge carb, but will it be able to meter at low air flows??

Such a stupid statement that the H carb is a 'tube' carb.....as if other brands are not. Can you think of an automotive carb that is not? I cannot. Even a Predator is a tube carb, rect, not round tube. D. Vizard says this about the P carb in his carb book.; ' The atomization that the P delivers keeps the low end output inline with a fixed jet carb, & the throttle response it gives is excellent.'

Like I said, Campbell should read page 8. The flow density through the carb is dependent on restrictions within the carb. When you watch dyno tests of AV carbs that have a camera above the carb, the AV opens well before peak rpm where the max flow [ with least restriction will be needed ] will be needed. Nicks Garage, Canada, has some video. The Holley sec carb has a venturi & a booster to reduce flow; AV carb has a vertical blade, thin shaft & dump tubes. So just bullshit to say that an AV carb can never make as much power as a H. I looked for some examples to disprove this nonsense, couldn't find any back to back tests [ other than the one I posted earlier ], but I found these examples which I think are pretty convincing:
[1] PHR magazine pulled the engines from the popular muscle cars of the time to dyno the small block engines & see if they made the adv HP. Chev, Chrys, Buick, Olds, Pontiac were tested. Only one produced the adv HP, the Chr 340. It actually made 20 hp more, 295 hp v 275 adv!!! Not only that: 'And, to top it, the 340 would rev up to 6500 rpm...' The 351 Ford got the lowest hp, 210, adv 290. It had a Holley or it's Autolite cousin. The 340 had a 625 Carter AVS. Published in PHR, Feb 1969.
[2] Car & Driver tested the 'Econo Racers' in Jan 69. Basic, no frills models, showroom condition.. Chev, Ford. Chr & Pontiac. Cars were scrupulously checked for originality & Pontiac was disqualified for cheating. MPH is the best predictor of HP over the 1/4 mile. 383 Dodge v 428 Ford. Both 3.5 diffs, Ford was 125 lb heavier. But it had 45 extra cubes, more tq, & higher CR 10.6 v 10.0. Both rated at 335 HP. Dodge ran 100.61 & 100.89 for the Ford. Ford had a Holley, 625 AVS on the Dodge.
[3] And then there was Roger Huntington's tests. 61 Dodge 413, 385 adv hp, 92 mph. 427 Ford, 427 adv hp, ran 87 mph. Both had 4.1 diffs. Dodge had a 3 speed manual, Ford a 4 speed. Estimated HP by RH was 270 for each. Dodge had dual AFBs, Ford had dual Holleys.