Dumb history question for the carb guys

[Bob Hollinshead]

With Modular design comes engineering compromises at best.

Why were Thermoquads and Rochesters still used well into the emissions period by the OEM's before FI and not Holleys?

Hysteric

Holley was still being used in the mid 80's till fuel injection took over, the Ford 5.0 is a good example

[Bob Hollinshead]

And the OEM Holley carbs had a lot of differences in booster designs and metering, look at some of the holley ford carbs, holley mopar carbs, and holley chevy carbs and there was some big differences between them, heck even AMC and International ran some holley stuff I think.

[harleydrjr]

I got out Smokey's "Lil' skinny rulebook & eatin' an elephant" and on page 192 He gives Ralph Johnson 75% of the credit for inventing the 4150 holley by enlarging a "goofy Holley truck carburetor" to 1-11/16 throttle plates. He claimed it was half bondo and idled shitty. He also never got it back... Best books I have ever purchased.

[hysteric]

Holley was still being used in the mid 80's till fuel injection took over, the Ford 5.0 is a good example

I stand corrected. Looks as though they had to go to an annular booster to get it to pass emissions. We never got the mustangs here in OZ.

Hysteric

[englertracing]

Something I've always wondered.... How did the the Holley design get to be the #1 carb choice among the street/strip crowd?

I've always been more into "drivers" than race cars, and I never really paid much attention to the inner-workings of Holley carbs. I've recently been reading a bit trying to understand the various circuits and operation of Holley carbs.

In my opinion, it really seems like a crude design for anything other than WOT when you compare it to a Q-jet, Thermoquad, AVS, AFB, etc. Particularly the power system. Also, the number of seals, gaskets, and other loose parts seems to put it at a real disadvantage when compared to almost any other carb design. The Carters and Rochesters just seem more "refined", and all of them can work on most applications if tuned properly.

So the question is, what features made the Holley so popular with the street / strip crowd? I can't help but feel I am missing something, but I just don't get it. Can someone enlighten me as to why it has become "the" carb to use? When did the Holley design really take over the marketplace, and why?

IMHO, for racers the appeal of Holleys is the same as for Webers, profound and convenient tunability in the field.

did you really just compare a holly to a weber?
???

[barnym17]

I think it is because it is so simple a design,easy to understand how it operates and tuneability.It is not quite as precise in fuel metering at different throttle openings and load conditions as a qjet but it really doesn't have to be either.It is also not nearly as complicated to get and keep working right as one.Plus it has many other advantages over the qjet such as dual float bowls allowing much more volume of fuel to be available which can be a problem with the Rochester. Sometimes it occurs to me that a holley is like a bowie knife compared to a scalpel ,they'll both cut meat well but how precise do you really need to be to get the job done? In the racing world and most performance applications we are not really worried about emissions control,ultimate fuel economy etc.and a multitude of sins can be covered up by adding a little more fuel. Holley themselves tells you that the 4150 series is calibrated to rich for emissions use and ultimate fuel economy.
Whereas Qjets and oem Carters had to meet emissions and fuel economy standards as well as driveability Aunt Tilly would accept on her Caddy.Holley had to make major changes to the 4160 turning it into the 4180 in order to be acceptable for just a couple of years on Ford vehicles in the 80's.I am not saying a holley is not capable of very precise metering in the hands of an expert tuner just that out of the box they don't really have it compared to other carbs.
In the end it won out despite of these things because the other advantages outweighed precision metering of other designs,myself I prefer a little less precision if it gives the ability to get real close real easy as opposed to dead on real hard.And they sure do look good on an engine don't they?

[Bob Hollinshead]

Holley was still being used in the mid 80's till fuel injection took over, the Ford 5.0 is a good example

I stand corrected. Looks as though they had to go to an annular booster to get it to pass emissions. We never got the mustangs here in OZ.

Hysteric

They ran that basic 4180 design on 351HO and also 460's during the 80's also, bronco, truck, van.

[buddy rawls]

I am a huge fan of the 4150/4160 designs. I am not going to tell you that they are vastly tunable. In truth, there is really very little special tuning you can do to the common holley list numbers. Heck, you have jets, and power valves, for the main system. But, simplicity can be an equally important trait. Thats very high on my list. Obviously, I'm not going to consider idle mixture and speed, those are external and common to virtually all carbs). Likewise the vacuum operated secondary systems are quite similar across the carb designs. Double pumper is a very cool holley only design.

I had an AFB on my rat truck. It was a very high velocity ( crazy high!) ford 300 six. The AFB that came on it worked very well, but I was never happy with the off-idle drive away. Essentially the accel pump to main circuit behavior just want crisp and quick. I absolutely know it was related to port velocity. With all the bells and whistles (very intricate tuning components) available for the AFB, i was lost. On top of that, they werent cheap. For kicks and grins i stuck a holley 1850 on it, played with shooter size and cam, and check plugs for jetting, made the appropriate chAnges. I had to jet the carb down a few sizes because inlet port velocity was so high. The truck came alive to my liking. The additional tuning aspects of the holley were simpler and cheaper. In the end, the AFB went back on it, because the overall look of the carb orientation looked better, sitting on the side of the inline six cylinder. The afb was in line with the valve cover, where as the holley was 90deg, opposite than on a typical v8 manifold.

This leads me to the accel pump system. When others complain about the tunability of the holley main system being archaic and limited (common list number carbs) in tunability in comparison to the AFB and quadrojet, they are right. However, the accelerator pump is a whole different ballgame and the pendulum swings to holley quickly. This aspect is very important, because this is what people see when tuning a carb. The instant rev and drive out. This is accel pump tuning at its core. The holleys have this. And the ability to tune this with the double pumpers is simply awesome.

Holley pluses:
Look good on a V motor
They have a very simple tuning (jets and powervalves).
They have vastly tunable accel pump system, than can be instantly felt (throttle resonse) not just measured with a dyno or ET.
Plentiful in the used and new markets.

Holley cons:
Main circuits are archaic and limiting
Typically dont look as good sitting sideways on an inline motor

[peejay]

did you really just compare a holly to a weber?
???

In the respect that jetting changes are relatively painless, yes.

It'd be nice if you didn't have to drain the bowls to access the jets, but at least you don't have to disassemble half the carb. Although the Holley is so simple that by the time you pop the bowls off, you DO have the thing half disassembled.

Mind you, I don't like Holleys much and I think a Q-jet is a much better driving carb, but Holleys are much more friendly to play with. Everything is right there and accessible. Personally, though, I don't bother to do it on the car since I don't like fuel staining on those nice cast aluminum manifolds, so I pop the carb off and flip it upside down over a quart bottle with one of the sides cut out. The bowl vents fit perfectly over it. With a cap from a gear oil bottle on it, you can even re-fill the carb through the bowl vents once you get it back on the engine.

[BrazilianZ28Camaro]

Talking about Holleys, who messed with spread bore 650s dual pumpers and want to share experience????

[levisnteeshirt]

I think the best part, if a Holley does have a problem, its so much easier to fix. I think they went cheap in areas that hurt them. I'd like to try a 1850 600 with 4 corner idle and a rear power valve, the idle circuit could be tamed a little to help mpg ,, then the power circuit could be tuned in for what it is for

I've got decent mileage with a 1850, if i changed air filters frequent, i like em

[289nate]

Are we meeting up at a cruise night or at the drag strip to settle this?

[tresi]

Back in the day holleys were cheap. Without metering rods, pistons an the like they are a lot cheaper to make. This is only one factor but it's a big one.

[Barry Burch]

Trying to better throttle response with accelerator pumps is a
case of to little to late. Accelerator pumps exist to prevent flat out bogs.
The idle and transfer circuit are more important. Speaking of unique holleys.
The 1950's Reo trucks had a skirted booster 2 barrol. I replaced an autolight
on a 391 work truck. Power response and mileage were noteably better.

[hysteric]

They ran that basic 4180 design on 351HO and also 460's during the 80's also, bronco, truck, van.

They went to the thermoquad here in OZ in 1977 to meet emissions on Ford V8's

Hysteric