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
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
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.
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..
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..
I'm sure the HP with the milled air horn is flowing more air, especially in the primaries, hence the need for larger jets.
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.
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
Actually Douge, would you say a Holley or a Demon is more complicated then a Webber? Can you imagine tuning 4 Holleys?
Gary
Gary
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.
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.
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
They can all be tuned when you drill/tap inserts. This is mine:
http://www.rc-tech.net/cars/panttransam/1905/bleeds.jpg
http://www.rc-tech.net/cars/panttransam/1905/feeds.jpg
Gary
http://www.rc-tech.net/cars/panttransam/1905/bleeds.jpg
http://www.rc-tech.net/cars/panttransam/1905/feeds.jpg
Gary
Gary don't the screw drivers get in the way of the air cleaners?
Nah, not if you fire up the engine first. They get stuck in the throat of the carb and then the breathers fit fine!
Gary
Gary
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!
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:The Holley has emulsion tubes too.............
OK, everyone finished cussin' now? You just can't change 'em...yet. Yeha!
My brother tapped and put incerts in those two:
http://www.pro-system.com/graphics/carb6.jpg
That was one of the adjustments he made in his dominator. He's running a bored/sroked 460 685 rwhp. Everyone told him the dominator was not streatable. It was!
Gary
OK, let's take a survey now?
Who wants all the jets, air bleeds, auxiliary venturi's...Emus to go away?
I say this will all due respect, which is a lot. Your brother is crazier then I am.
Who wants all the jets, air bleeds, auxiliary venturi's...Emus to go away?
I say this will all due respect, which is a lot. Your brother is crazier then I am.
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
Gary, I'm into this stuff. I have a headache from it.
I'll be back when I recover.
I'll be back when I recover.
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
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
Demon seems an appropriate name.
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.
I ordered my Holley HP 750 DP 82751 from an Ebay vendor last night. Saved an addition 20% off of Jegs/Summit which was very surprizing as they typically have some of the best prices, got free shipping and got a T-shirt to boot!
Thanks all.,, great thread.
Thanks all.,, great thread.
John, the "T-Shirt" changes everything!
Gary
Gary
LOL
Yea, I wasn't going to buy it, but when I discovered the free shirt, hey, how could I turn it down.. LOL
I can add it to my other 200 (unworn)T-shirts in the closet. LOL
Yea, I wasn't going to buy it, but when I discovered the free shirt, hey, how could I turn it down.. LOL
I can add it to my other 200 (unworn)T-shirts in the closet. LOL
quote:Originally posted by johnk:
I ordered my Holley HP 750 DP 82751 from an Ebay vendor last night. Saved an addition 20% off of Jegs/Summit which was very surprizing as they typically have some of the best prices, got free shipping and got a T-shirt to boot!
Thanks all.,, great thread.
Is it custom jetted or box stock?
The carb or the Shirt??
Ah ha, yup...ok
- Holley 700 DP (no idea about the size of the jets)
- Street Dominator manifold
- Bone stock OC Engine
- approx. 14 mpg
In general, it's a lazy engine....
- Street Dominator manifold
- Bone stock OC Engine
- approx. 14 mpg
In general, it's a lazy engine....
JohnK,
Who was the vendor?
Who was the vendor?
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
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
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??
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.
72 primaries, 78 secondaries is a good place to start.
Doug, I looked at the Holley site, I looked at an old Holley book I had, and I just plain can not find out what a 5534 is. Leave it to me to have a total one off unkown carburator. 
The Holley listing skips right over the 5000's. I never noticed that before. That's very strange.
Is ther a nother number stamped into the airhorn besides the date code?
Is ther a nother number stamped into the airhorn besides the date code?
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
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