What carbs are you using on your Cleveland motors?

Had a Holley 600 vacuum secondary, switched over to a Holley 600 double pumper.

And you like the throttle response of the larger pump shot and mechanical secondaries, right?

Every characteristic changed. Power, response oh mileage went down too!

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

Im using a Demon 650, goes great!
Dennis

I use Holley 670 Street Avenger. Except for choke and idle speed adjustment it has been great. I'm at 750 feet above sea level and that seems pretty close to the flow setting used at the factory.I replaced a 750DP which was way too rich at idle

Speed Demon 650 replaced a tired original factory carb. Nice idle pulls very strong. Excellent Barry Grant tech support.

sorry, I have SVO windsor. I need to read the questions better.

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.

This is a great acrhive..lotsa gems reguarding tuning.
http://realbig.com/pipermail/detomaso/2003-June/028198.html

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

Hello Mick,,, Yes, please post some pic's of your car. It is tuff looking. Blue is very nice looking on the Pantera. I would like to get a good look at the rims.

Holly 750 DP. 72 Primary and 80 Secondary.

Holley 650 DP

Holley double pumper of somekind. Not real sure what number it is. Where does it say????

quote:

Originally posted by Coz:
Holly 750 DP. 72 Primary and 80 Secondary.

With an 80 secondary jet you gonna have a raw fuel exhaust plume. I hope it doesn't backfire.

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).

Holley 770 Street Avenger. Runs strong, passes emissions and gets pretty good mileage to boot.

Thanks doug, I will look this weekend.

Better to be safe then sorry I say.

Dont leave out the older 4150-735cfm, from the 390-428 engines.

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]

Maybe we can all post general motor specs, carb and jet sizes so others can get a base line for jetting? I run a basically stock motor with a 600 DP 65/70 and its running a bit rich. I had a set of 59 jets and tried them, the car ran way lean. I think 62's would be optimal.

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

Interesting.

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

I was figuring although there are so many factors in jetting a carb, at least someone new could get a "ballpark" start without spending a mint buying jets. A reference of a similar setup may get them into the correct area from which they could fine tune.

If you had something people could enter nearly everything relevent, make it so they could submit it even with limited info such as just jets. The info could be viewed as simple or indepth as it comes.

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?

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

I put extra bungs in the MGB exhaust (GM 3.4L V6) because I am going to play with balancing the cylinders:

Gary

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