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Day in, day out, the right carb for a standard displacement 351C is a 750 Holley (equivalent to a 650 Demon). Vac secondaries will improve fuel economy, double pumpers will improve throttle response.

In times past, the Holley always required tuning to work properly, they were always too rich out of the box, with insufficient accelerator pump for a Cleveland. I've no experience with the new flavors of carb Holley is selling, if any of them are close out of the box, I doubt it however. The message here is, don't expect to buy it, bolt it on & have the motor pull strong at every rpm without stumbles or bogs.

Running a smaller carb is not a cardinal sin however. It will have stronger signal at low rpm, with the trade off being less torque at higher rpm, and the motor will flatten out sooner. The 750 CAN be tuned to pull just as well at lower rpm as the smaller carb.

The 600 cfm street carb is a Chevy camp thing. That's the carb that is always recommended by the magazines for the sbc operated on the street. The sbc is a high velocity motor that weezes through a set of small intake ports. The Cleveland is a whole different animal, Chevy rules do not apply.

In the '70s & '80s, building motors for clients in California meant having to build a motor that could pass visual inspection & tailpipe emission smog testing. I tuned & built several hydraulic cammed motors with power outputs between 350 to 400 bhp using the spread bore Autolite carb (4300D). That carb was rated by Ford at 750 cfm, I'm sure it flows at least the equivalent of a 700 cfm Holley. I have left the 4300D carb on my motor, I see no reason to change it, there would be nothing gained in doing so. This carb is not as adjustable as a Holley or Demon, and the fuel supply system will run out of steam at some point, but installed on a motor with good vacuum signal at idle & cruise, making 400 bhp or less, this carb works OK.

Your friend on the DTBB, George
Thanks Guys,

I have what appears to be a 600CFM 4160 series vac secondary carb currently on the motor. Personally, I've never been a fan of 4160s on a manual trans car. I was actually looking at the 4150 model 80528 Holley Pro series, 750cfm w/ mechanical secondaries. Looks like PI sells it as well, but difficult to tell from their description whether (they) tune/jet it close by application or if it's an out of the box 80528. Hard to tell whether this carb has the large PB vacuum port. I see that the throttle bores are opened up an additional 16th". Anyone run one?

http://www.holley.com/0-80528-1.asp



Perahaps a better starting point for my stock-ish rebuilt motor would be the 82751, also a 750 MS carb, 4-corner idle adjustment, standard 1 and 11/16" throttle bores, looks like it comes with 75/80 jets and 31/28 pump nozzles. The picture of it does reveil the large PB vacuum port. I've got a master jet kit on the shelf somewhere but haven't opened it in a while. Mike Ulrey did a masterful job (as always) on the restoration of the original Holley 780 (and distributor) on my BOSS car that required no further tuning, and Craig Conley did the modified Holley 700 DP on the Paxton/GT350. It too was dead-on.. Thanks all, comments/suggestions much appreciated.

http://www.holley.com/0-82751.asp
I don't know about all you guys, but I will never buy another holley. I had a 600dp and it worked great if you wanted to keep the mosquitos away. After a few months of driving the engine started to develop a stumble. I,ve owned several holleys over the years and all made my engines stumble after a few months of use. I've started running the Eldebrock750 and have had no troubles for 2 years and it installed with minimul adjustments. also, I had an increase in gas mileage by 2 to 3 MPG. Overall the car performs better and doesn't keep the bugs away.
I would recommend a 4779, Holley 750cfm double-pumper. If you are in a state that is still going to smog test you, then it is probably going to be too dirty at idle for you.
It is intended as a race carb and is already rich at idle to compensate for the leaning out that headers do to the engine.
The idle air bleeds can be leaned out some. Since this requires enlargening them with a pin vise (drilling them larger) you need to know what you are doing with them. Once you go to large, there is no going back.
I ran mine with a "weber plate". This let me change everything with drilling out anything.
quote:
Originally posted by micks74:
...I've started running the Eldebrock750 and have had no troubles for 2 years and it installed with minimul adjustments. also, I had an increase in gas mileage by 2 to 3 MPG. ...


Mick, nice looking car in your avatar, I assume that's your '74 Pantera. The Edelbrock carb was originally known as the Carter AFB, and yes, it is a great carb. Nothing wrong with that choice at all. You are right, the oem carbs like Cater, Autolite, Rochester, etc are less fussy than the Holley. The Holley is very adjustable and lends itself well to modification for motors in a very "non stock" state of tune. The Holley fuel bowls will support tremendous amounts of horsepower. That fuel bowl was designed by Smokey Yunick specifically for racing.

When you get a chance, post some pics of your car in the photo gallery, introduce yourself in the pub. In the meantime, let me welcome you to the deTomaso bulletin board, it's a pleasure having you with us.

your friend on the DTBB
Started with a Holley 4778 700cfm double pumper on an Edelbrock Torker manifold.
Ran well - but only did 8mpg (US gallons).

Then tried a Holley 4160 1850S 600cfm vacuum secondary with a 4150 conversion kit to replace the metering plate with 'proper' jets.
This improved the gas mileage to 10mpg and felt the same on the road. Dynoed at 310bhp.
Had to lean off the primary and richen up secondary - now on 64 primary and 68 secondary.
I also removed the cold-start mechanism completely.

I've now changed manifold (to a Performer) and I need to start over with the jetting.

It's not easy to find a Cleveland and Holley expert in the UK - they are few and far between.
Often people change carbs quoting one carb much better then the other when really they never even tuned it. By tuning I mean really tuning it not just a jet change. Most carbs being Holley, Deamon, or Rochester can be very very good carbs if tuned. If you compare one carb out of the box with out doing anything to it against another out of the box carb, it means nothing.

That being said I am leaning toward Deamon. Deamon being much like a holley except with changable bleeds and an adjustable air bypass. I am putting one on the 434 being built. Deamon is giving you control over things Holley doesn't want you touching.

I have a 4140 series carb now (choke tower and carb numbers cut off). I have drilled an tapped the bleeds and feeds replacing them with brass incerts (with the help of a superior carb friend)on this one making it very very responsive. I look forward to messing with the deamon (before I put the Webbers on it).

By the way, if you plan on tuning your car in this day an age, just get a wide band. Just do it. It takes the gues work out of everything.

Gary
No backfire, no smoke, just get up and Go !
I've tried 76 & 78's, just doesn't run as good as it does with the 80's when pushing the gas peddle through the floor...which I rarely do :-)

Holly 750 DP. 72 Primary and 80 Secondary.[/QUOTE]

With an 80 secondary jet you gonna have a raw fuel exhaust plume. I hope it doesn't backfire.[/QUOTE] Roll Eyes Roll Eyes
Dennis,

What a great idea, there is so much discussion on general engine specs and engine building. I know George does an excellent job as "Cleveland Guru" of answering all the questions, but a database could give an added dimension.

If it works out for engine specs, maybe we could take it even further to develop a database of general upgrades and modifications.

Julian
If there was a jet database, it would be important to have a wideband refference to go along with it which would be a lot better then generalities which can mean so much to different people. I have seen cars shoot out a smoke trail from being so rich and still talk about how great it runs. In fact a lot of data would be good including everything from jet size, booster size and type even to bleed and feed sizes. And then it would be important to have cam specs, cyl head info, compression/piston info, etc.

Even if 9 out of 10 are unrelevent, it may be possible to match up with 2 similar and compare notes.
Gary
So, are you going to run a certain set of jets in your just rebuilt $10,000 motor because Willard G. Misfit says he runs them in his Pantera, or are you going to take it to a dyno operator and let him tune your car for you?

Maybe ol' Willie has burned holes in his pistons, but forgot to mention that when he sent his jetting info to your data base.

I find most owners don't even know how to set the throttle plates properly.

Proceed with caution young Jedi.

Your friend on the DTBB
No kidding George, that's why you make it possible for people to put lot's of info in or small amounts of info and add some latter. No one even indicated they are going to build a $10k engine and base their jet's on what Joe Shmoe is posting on the internet. But who doesn't take a factory carb and and throw in on an engine "as is" and see where they are. If everyone was running one set of jets and you find your carb way from norm even a small amount of info could be usefull. We will never get a large amount of info if no one is even willing to start something.

Gary
There are a large percentage of Pantera owners who would turn a wrench over other marques. I don't see too many people involved in these discusions having some one do carb work or change their oil. The people here tend to largely be wrench turners even if they haven't done a lot of it. Carb jetting info is one source where the internet is weak on numbers and it could be quite usefull. This is especially true if people would include lot's of info including wideband O2 info (as said earlier). Even if just a couple people did it the discusion from the info would help everyone learn.

Gary
I bought an edelbrock exhaust analyser. It is the simple one that just shows green lights for the mixture strength and uses a Bosh oxygen sensor.
On a non computerized car this is about as sophisticated as I will get.
I don't know where I'm going to put the bung yet. I don't really want to cut into my headers. I'm wondering how accurated the sensor would be clipped to the tip of the muffler?
Last edited by panteradoug
I have an LM-1 and it is one of those tools I will never do without.
http://www.innovatemotorsports.com/products/lm1.php

I have been tuning the Transam, the Pantera, and even the Ford 8N tractor. I hooked it up to the tractor after putting the new engine in, warmed up the tractor on a hot day and tuned it while mowing some heavy grass. Aswome Awsome tool! Dyno is fine for jetting but LM-1 is great for working out transitions (and jetting if your not going to dyno). It simply takes the gues work out of what you are doing. Worth every penny.

Gary
Last edited by comp2
The problem with the exaust analizer is they are generally set on 14.7:1. This is a rich setting for cruise and a lean setting for power. 14.7 is standard because any hotter and the nitros oxide emissions get worse due to the increase in heat.

Everyone always states that back in 19xx they developed a carb that got 10000mpg. Well, the EPA emision standard pretty much require a mixture richer then what cars are capable of running on. Limmiting cars to a rich mixture as they do limits the advancement in lean running engines.

Gary
My car had an Edelbrock on a mild 351 when I bought it. Runs great. No need to mess with it. Previous owner had bills for a few different Holley's and distributors. He wasn't a wrench, didn't even change his own oil. All were installed and tuned professionally but when the Edelbrock was installed and tuned, it was right.
quote:
Originally posted by george pence:
Day in, day out, the right carb for a standard displacement 351C is a 750 Holley (equivalent to a 650 Demon). Vac secondaries will improve fuel economy, double pumpers will improve throttle response.

In times past, the Holley always required tuning to work properly, they were always too rich out of the box, with insufficient accelerator pump for a Cleveland. I've no experience with the new flavors of carb Holley is selling, if any of them are close out of the box, I doubt it however. The message here is, don't expect to buy it, bolt it on & have the motor pull strong at every rpm without stumbles or bogs.

Running a smaller carb is not a cardinal sin however. It will have stronger signal at low rpm, with the trade off being less torque at higher rpm, and the motor will flatten out sooner. The 750 CAN be tuned to pull just as well at lower rpm as the smaller carb.

The 600 cfm street carb is a Chevy camp thing. That's the carb that is always recommended by the magazines for the sbc operated on the street. The sbc is a high velocity motor that weezes through a set of small intake ports. The Cleveland is a whole different animal, Chevy rules do not apply.

In the '70s & '80s, building motors for clients in California meant having to build a motor that could pass visual inspection & tailpipe emission smog testing. I tuned & built several hydraulic cammed motors with power outputs between 350 to 400 bhp using the spread bore Autolite carb (4300D). That carb was rated by Ford at 750 cfm, I'm sure it flows at least the equivalent of a 700 cfm Holley. I have left the 4300D carb on my motor, I see no reason to change it, there would be nothing gained in doing so. This carb is not as adjustable as a Holley or Demon, and the fuel supply system will run out of steam at some point, but installed on a motor with good vacuum signal at idle & cruise, making 400 bhp or less, this carb works OK.

Your friend on the DTBB, George


Thanks George,

For a stockish motor, good ignition, Performer intake, what jets would you suggest are a reasonable ..starting point... for a Holley 750 DP with 28/31 pumps? Sonething that might be servicable until warmer weather arrives here ont he East Coast and we can schedule a trip to the dyno?

Thank you

John
John,

In 1970 or 1980, if you purchased a list 4779 it had #75 primary jets & #76 secondary jets out of the box. The list 3310, 780 vacuum secondary, had #72 primary jets.

The new carbs are jetted better than they were 20 to 30 years ago. Today the list 4779 carb is equipped with #70 primary jets & #80 secondary jets. Although the older list 3310 was equipped with #72 primary jets, it ran rich. This leads me to believe the fixed jets in the modern carbs are also calibrated leaner.

For comparison, the 770 street avenger (list 80770) has #72 primary jets and #75 secondary jets. The 750 HP carb (list 80528) has #72 primary jets and #84 secondary jets.

If you have any of these modern carbs with #70 or #72 primary jets, I say run it as it came out of the box until you make it to the dyno. If you have an older carb, stuff it with #70 primary jets & #80 secondary jets. While you have that older carb apart, purchase on of those new "re-usable" gasket kits, they are worth their weight in gold.

Set the primary & secondary throttle plates properly (transfer slots exposed below the butterflies at idle), attach the carb to the intake. If you're running a vacuum advance, hook it to "ported" vacuum. Start the motor, set the fuel bowl levels. Adjust the idle jets (for highest rpm / best vacuum). Optimize your static ignition advance setting (highest rpm / best vacuum method). This will get you off & running.

By the way everyone, the jet recommendation is only good for a Holley 750 cfm carb.

Your friend on the DTBB
Last edited by George P
If the size of the jets has been reduced in the 4779-2 or -3 that means the the idle air bleeds, main bleeds, have been enlarged to reduce the air/fuek ratio. You can measure them with numbered drill bits. I'll look at my -2 but the 4779 to compare it to is long gone.
Now if you guys want to chart anything the model number of the carb, the fuel jets, the air bleeds all need to be charted.
My Holley Weatherly index is old and hasn't been printed since the 70's. It can't help on the current production of Holleys.
Thanks all.

Limiting the discussion (for me) to the Holley 750 DP, I see 7-8 iteratrions of 4779s on the Holley tech site that run from almost square jetted 75- 76s (with a small pump nozzle) to several in the 72-80 range. I'm looking specifically at the 82751 HP flavor which comes with 75-80s and 31/28 nozzles. Although initially it seems to run a richer primary circuit, it also has the milled/radiused body, choke housing removed, and adjustable air bleeds, which presumably would require fattening up on the jetting to achieve the same overall AF ratio, but I suspect something on the order of 72s or 73 on the primarys would put in (initially) in the ballpark. ???? Thanks all..
You have to consider the size of the idle air bleeds and the main bleeds.
What you guys are getting into is as complicated as jetting Webers but you can only increase the size of the air bleeds (air jets) since they are pressed into the carb housing.
Try a 750 DP out of the box and see how it idles and runs.
72-73 front, 76-78 rear should be about right.
If you need more in the rear you might want to consider a secondary power valve with a real late opening like 2.5 or 3.o.
quote:
Originally posted by PanteraDoug:
You have to consider the size of the idle air bleeds and the main bleeds.
What you guys are getting into is as complicated as jetting Webers but you can only increase the size of the air bleeds (air jets) since they are pressed into the carb housing.


I am with you there. which is why you really can't compare the jets of todays after market carbs to the listed jetting 30+ years ago. Most carbs off the shelf typically start on the rich side anyway which is safer for the manufacturers and the users.

I would love to see, compare, and discuss what different people are doing and how they are changing it. Most carb discusions talk mostly of just jets and power valves. There is so much more to them. It may be more then many people would like to get into but I enjoy it. We have been making some changes to some carbs we have been working on adjusting everything from the bleeds to the emulsions and we have been succesfull at getting the these things to run like they are fuel injected. We are not always 100% confident in what we are doing but that is the learning process and that is the fun!

Non of this would have been remotly possible without an LM-1. When working with trasitions for examle, we can accelerate moderatly and see for example "wow, fuel/air went to 9, now it's catching back up". You question what is going on as you are driving it. You look at a fuel to air ratio meter and there are no questions. You see exaclty when it goes rich, under how much load, watch the rpm, etc. You can see things happening even before you hear the effects.

Gary
quote:
Originally posted by PanteraDoug:
I haven't played with the Demons yet. I would say that the Holley is actually more complicated to deal with the the Webers.
It is not really a great comparison. It's like asking if I would rather be eaten alive by a lion or a bear? Thank God dem Emu's don't eats no meats.


Exactly!
quote:
Originally posted by PanteraDoug:
You have to consider the size of the idle air bleeds and the main bleeds.
What you guys are getting into is as complicated as jetting Webers but you can only increase the size of the air bleeds (air jets) since they are pressed into the carb housing.


The Holley 750 HP carb has tunable air bleeds.

Thanks
John
The Holley HP series carbs are what one needs to tune the air/fuel ratio on the car, if your car doesn't need a choke. However lets not try to be too intelligent here it will likely make us look very stupid.
These are really no easier to "tune" then the Weber IDA's are. No harder for that matter also.
The Holley advantage is you don't have all that linkage being directed in ways it doesn't want to go and you only need to deal with four throats instead of eight.
Your guess is as good as mine as what the proportion of fuel to air is going to be.
It is unlikely that they will be the same as the Webers of 140/160 on the Cleveland.
The single carb plenum has a diferent requirement then the IR manifold does.
Then once you find the ratio you need to find the size that the fuel jet should be. It is possible that you might find the main fuel jets should be small, like a 62, but I doubt it.
Incidentally, I hate to tell everyone this. Don't hate me for it.
The Holley has emulsion tubes too.............
OK, everyone finished cussin' now? You just can't change 'em...yet. Yeha!
quote:
Originally posted by comp2:
...we have been succesfull at getting the these things to run like they are fuel injected...None of this would have been remotly possible without an LM-1...


I agree with you Gary, there's nothing like a carb tuned to perfection, the motor runs crisp and tight. Or as you wrote, like it was fuel injected. The air fuel ratio meter sounds like a cool tool.

In the days before such a device was available, I used a long stretch of unused road with an uphill grade, I would make each carb adjustment one small step at a time until the carb became too lean, and then back off one or two steps (except for the air bleeds). It was quite time consuming. The first few carbs were a challenge, it was fun learning to do it. But afterwards it became tedious, it was far easier to just pay a dyno operator. If a tool such as an air fuel ratio meter had been available, I may feel differently about it today. At this stage in my life, with the limited spare time I have, I have other priorities that I would prefer to budget time for, rather than playing with a carb. But I can relate to the passion you have for tuning on the carbs, that's cool. There's nothing like working on something, and the result being it performs better afterwards.

Your friend on the DTBB
quote:
Your brother is crazier then I am.


I resemble that remark!

You think we shouldn't talk of it? I think carbs are a black art which shouldn't have to be. I think going from general discusion to specifics and numbers would not not only be fun but open up understanding to many of us (including myself). This is a good start here:

http://www.bob2000.com/carb.htm

There are several other tuning sites out all a little different. There is a lot to learn and people seem to just thow it in a box and go fuel injected instead.

I think the LM-1 makes it possible for people like myself to even think about making changes.

Good stuff.

Gary
LOL,

Well I have ehausted the theory part, this spring maybe we can revisit it when I break in my new stroker. I am putting a Demon on it which they say is more adjustable then the Holley. Holley doesn't want you touching this stuff, Demon realized guys were so it's supose to be much more adjustable. I will let you know when I get into it.

Gary
Last edited by comp2
For those that requested some pics I put some up for you and for those with headaches... Sorry. I got tired of the holley headache and bought a Eldebrock 750 and cured all my problems. I have a .030 engine with SVO heads, modified performer intake to fit heads, crower solid roller camshaft and I get 15-17 mpg around town. est 400+ horses. Good luck to those making the choice.
The new carb and accessories arrived today. Man, when Holley says the HP carbs are wet tested, they mean it. Carb was wet right out of the box, and good thing I wasn't looking up the pump nozzles when I winged the throttle on the work bench, pumps were still full and the bowls weren't completely drained. Neat carb with alot of nice features right out of the box. We'll see how well it works..

Thanks

John
Been using a 650 Demon on mine since I rebuilt the engine several years ago. Straight out of the box with minor tweeking on the idle jets. Not any dynos close to me so final adjustment will have to wait, but I'm very happy with the way it runs as is.

Bob
quote:
Originally posted by PanteraDoug:
quote:
Originally posted by DeTom:
Holley double pumper of somekind. Not real sure what number it is. Where does it say????


DeTom, there is a number stamped into the air horn on the primary side. The DP's are 4776(600),
4777(650), 4778(700), 4779(750), 4780(800), 4781 (850).

Dear Doug, I must have a hollet from way long time ago. It says 5534 on it. Does that mean it is not a very good one??
DeTom,

I don't believe the Holley installed in your car is an aftermarket version, yours was installed oem, as your Pantera was originally a European delivery. At some point, the Autolite carbs were replaced by Holleys as oem equipment for the European Panteras. My best guess is that the Holley became one of the standard upgrades for the GTS models.

your friend on the DTBB
Holy cow George. You are probably right. Dang, I keep running in to this all the time. My brakes ain't the same, my anttena is differant, my clock is not lock any of them. I mean I like that about my car and all, but when it comes to giving advice and stuff, I can't be sure of anything because so much is differant on my car.
And what if I have to replace a broken part or something?? I will probably have to have it custom made by some machinist in Lithuania who will take fourty years to make it.
DOH!!!
quote:
Originally posted by mikee:
I have a 735 cfm on the shelf and planning to install this soon. What jettings would you recommend on a stock engine?

quote:
Originally posted by cuvee:
Dont leave out the older 4150-735cfm, from the 390-428 engines.


Sorry it took so long, I was out of town... My engine is not stock, but I think my carb. had 80/74. The engine runs great but I think its running a little rich? Will try 78/72 when it gets warmer.
Yep Mr. Rapier. The number was 5534. Which I can't find anywhere in any of their literature, both past and present. So if I ever need to get a rebuild kit, I will have to call Holley and beg and plead with them. If I am pathetic enough they may just have me send them the carb for them to rebuild. Or maybe they will just laugh at me and give me a good price on their latest, handiest, dandiest fuel injection system for race cars. Either way, it just proves that owning a Pantera is indeed, an adventure. Smiler
quote:
Originally posted by johnk:
The new carb and accessories arrived today. Man, when Holley says the HP carbs are wet tested, they mean it. Carb was wet right out of the box, and good thing I wasn't looking up the pump nozzles when I winged the throttle on the work bench, pumps were still full and the bowls weren't completely drained. Neat carb with alot of nice features right out of the box. We'll see how well it works..


John,

How did this carb work for you? Still happy with it? Did it require a lot of adjustment or changes?
Don't kow how I missed this thread..

This spring I had my Pantera on the dyno to tune the carburetor, and we kept working at it until the mixture was correct for each test scenario. The general trend was to make things leaner. This is the result:

Holley 4778-2 700 cfm double pumper

Primary: jet 65, squirter .028, power valve 6.5, cam 466 (black)
Secondary: jet 76, squirter .028, power valve n/a, cam 466 (black) hole #2

Matching numbers block, 4v heads, Edelbrock manifold, upgraded valve train.

I'm now pleased with the throttle response, and the car no longer smells of gasoline all the time. We also found a few horsepower, with the final result being 335 rwhp. If what I read on another thread here is correct (20% loss through the drivetrain), this is approximately 415 bhp at the flywheel.

It could probably still be made better, but I'm not going to bother, because I'm in on the group buy for the quad Weber IDF manifolds. I'm looking forward to having those on the car.
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