So I have the old carb out and the rebuilt one mounted but I am confused about some things. There are far more connectors on the new versus the old. I'm sure I know some of it but want to be 100%. I have a pic below, numbered. They all look like vacuum connectors so can someone label 1, 2, and 3? My thoughts:

1)for the choke, but since I'm using electric option i have capped it
2)no clue
3)i'm guessing this is the main line that goes to the vacuum advance

There are also double the number of adjustments. How do I know which is the idle adjust screw? I looked at several illustrations but since this is a modified carb it doesnt match the pics.

Can someone please help out? I would really appreciate it.

Thanks.
Shane

 

I’d say that #1 should attach to an exhaust heat source. It keeps the electric choke system from closing every time you shut the engine off. The heat from the exhaust keeps the bioelectric spring open to keep the engine from running rich. #2 is manifold vacuum say for a pvc valve. It can be capped if you have the pvc valve hooked to another manifold vacuum source. #3 looks like a timed vacuum source like for a vacuum advance distributor.

 

Thanks for the help, that helps a ton.

So #1 should definitely be connected? I'll have to find a nipple to connect it to. The old carb only had one vacuum line, and it went to the vacuum advance on the disto.

thanks again,
Shane

 

I have to disagree.

#1 is choke vacuum.
It needs air being pulled over the bi-metallic element because electricity is flowing the whole time the engine is running.
Otherwise the element will overheat and burn out prematurely.
(this should be outlined in the Holley manual for this carb. they are all available on Holley's website)

#2 is manifold vacuum and could be used for PCV or anything else on your trucks vacuum diagram that requires it.

#3 is timed, or ported vacuum and comes from just above the butterfly.
No vacuum with the throttle closed, lots of vacuum at small throttle openings and little vacuum at WOT.
Many use this to control their distributor vacuum advance and it works well IF their distributor is set up correctly for it.

 

No drama, huh? Just a wrong answer to start with. Like I said you aren't smart enough to do this without major help.

 

I did look at Holley's site but didnt see a layout like the one I have. I also couldnt find anywhere on the engine that this could connect to. Any pointers on where to look?

I did connect it to the disto advance, like the last carb. I have a few other things I'm doing at the same time so its not ready to try and crank yet. I'll try tomorrow and see where we are.


As for you. You are a small, petty man with a miserable life that comes to an anonymous forum with a little knowledge and thinks that grants him some power over others. A sense of power or knowledge not experienced in your own life. I wont stoop to your level and I dont have to defend my intelligence. I own a successful business, hold two degrees, and have a great family. I only come here for some camaraderie with fellow Ford enthusiasts and to learn a little about things I havent mastered yet. I dont have a need or desire to belittle or insult others, my self esteem is fine without it. This is the last time I'll acknowledge you on this forum so spam all you want and say whatever you will. It does nothing to me and only proves my point further.

Shane

 

I agree with Jim again tonight. Two for Two.

Craig

 

I'm sorry, I did not see where you mentioned what truck this is going in or what carb this is replacing. (do you have links to your other 'dramatic' threads? )

There should be a vacuum routing diagram on the radiator support of your truck that will show what else needs a vacuum source, like the fresh air servo motor if this applies to your year truck.
If you have everything else hooked up to ports or 'trees' on the intake manifold you could cap #2. Holley would ship a carb like this with a cap in place.

Did you modify this carb yourself or did you buy it from a remanufacturer?
What's been changed, and why?

From what little I can see in the photo it is dual feed, so obviously it is larger than 600 CFM.
It is vacuum secondary and has a single wire Motorcraft choke element meant to run 7+/-V.
Generic instructions for a 650cfm vacuum secondary 0-80783C can be found here: http://www.holley.com/data/Products/...199R9934-3.pdf

Without knowing a list or build number I can't be more specific.
Without knowing what it's replacing (I assume a 600cfm 4180?) I don't understand what you mean there are twice the number of adjustments.
The idle adjustment screws are the small recessed ones at the bottom, on each side of the metering block or jet plate directly beneath your #3.

I really don't have enough background to give you better answers.
Obviously there's been some 'discussion' about this before. I'm glad I missed that drama.

 

Its in a 78 F100 but little, if anything in the engine bay is original. This was my dad's truck and the guy he bought it from built the engine up and bracket raced it. The carb I removed was a Holley 600. I replaced it because it had met with alot of shade tree work-the choke had been removed and the butterfly wired open, it needed a rebuild, and had several other "engineering" feats performed on it.

I took the carb to my wife's cousin, a certified Ford mechanic, and he said it would be around 200-250 to fix everything wrong with it. I found this manufactured one for $150 on ebay. It is a Holley 750 double pumper with racing bowls (not sure what that means vs. standard bowls).

The engine has an Edelbrock Performer 460 intake, competition cam, dome top pistons, headers, oversized radiator, etc. so I would think the bigger carb would be fine-even though I'll probably get 2MPGs now.

So anyway, the original carb had the linkage, return spring, fuel line, and a vacuum line going to the advance on the disto and thats all it had connected so I was a bit surprised when I got this thing mounted and saw all the differences...

If I left anything else unanswered let me know, I really appreciate the help.

Shane

 

Edit: I forgot to answer your first question.
You could route the choke vacuum to the port in the #1 runner of your Performer manifold.

Where to start....

Without seeing the linkage on the other side I seriously doubt it is a double pumper.
The carb in your picture has vacuum secondaries.
750 cfm is a fine size for a slightly modified 460 intended to be driven on the street.
By "racing bowls" I assume the seller meant that this carb had angled fuel inlets and center hung floats. (nothing out of the ordinary)

Maybe you can post a picture showing the whole carb form the other side?

You would be better off routing the PCV to that port on the front of the carb where all cylinders see some oil mist rather than the port on the runner of the #8 cylinder causing knock and fouling that one cylinder.
The port in the #8 runner is a fine place to hook a brake booster.

The difficulty I see is not having any baseline on the settings and jetting of your "new" carburetor.
What accelerator pump cam and squirter it has. What secondary spring it has. What idle/mains it has. Where the choke's fast idle cam is set etc...

Try it out.
See if it runs well. If it bogs, runs rich or lean, how many turns out the idle mixture screws need to be set for highest vacuum.
You may need to buy some tuning parts. You might be able to use some parts from your old carb.

No one knows because your truck's engine is modified and you don't know what displacement, cam or compression it's using and this carb has obviously been messed with too...
We have no idea whether it was optimized for a 2000 pound small block powered race car or a huge behemoth 6000 pound Lincoln with an otherwise stock engine.

Hopefully the jetting is close and the secondary spring is not too light for starters so at least you can drive it and see.

 

The guy I bought the reman carb from said that it came off a 460 but who knows if that was the truth or not.

Here are some more pics...

 

As I said that carb would be well suited to a 460 but it is NOT a double pumper.

1) The Motorcraft choke element should connect to the black & white stator wire of the alternator, or regulator, if your truck has a 1G setup.
It requires 7+/- volts, not 12V like a common Holley choke with two connections.

It appears I confused the Performer and Performer RPM manifolds, or that Edelbrock has changed things since I bought mine.
The rear vacuum port is on the #4 runner of yours...
current PERFORMER RPM:

current PERFORMER:


2) You could remove the square pipe plug seen in the first photo directly above the fuel line fitting and insert a 1/4" NPT to 1/8" barb adapter. Then connect that to the choke vacuum nipple that you now have wearing a yellow cap with some rubber hose.

3) Connect the PCV to the front port of the base flange instead of the #4 runner.

I can't make it out, but you may be able to read the numbers found on the front of the choke horn.
This will tell you what it started life as.
With those numbers you can find;

Instruction manuals here: Carburetor Instruction Sheets, and other Technical Information

Spec sheets here: http://www.holley.com/data/TechServi...%20Listing.pdf

Basic exploded view: http://www.holley.com/data/TechServi...ded%20View.pdf

Just my 2c.
Hope some of this is helpful.
Good luck, and post back with your findings.

 

The guy at O'Reilly's told me it was a double pumper, because of the dual feed fuel line. What is the difference between a double pumper and what this is?

As for the PVC valve, where is it? I kind of looked around for it but not 100% sure what to look for. I'm still learning but this truck is a hard one to learn from since pretty much everything is shortcutted and installed wrong.

Some interesting findings so far:

• The old carb was held down with 3" bolts using larger nuts as spacers.
• The heater core has been bypassed but they didnt shorten the hoses any so they tied the large loops to the inner fender with electrical wire.
• The alternator adjustment bracket is a rectangular piece of scrap iron with a hole burned in one end and a nut welded to the other.
• The battery is held in place with a rubber tie down.
• I traced 11 different small gauge wires coming from the cab that are cut and tied off to different parts under the hood.
• I could just keep going...what a mess...

EDIT: Speaking of the intake, I'm thinking about replacing it. Would you recommend the RPM over the Performer?

 

It has dual feed because ALL Holley's larger than 600 cfm have dual feeds.

Only carburetors with dual accelerator pump discharge are "double pumpers".
A mechanical secondary carb would have this 'feature', but it's better suited to a lighter vehicle or one driven on the track.

The PCV valve is typically located at the rear of the passenger side valve cover.
It's purpose is to vent combustion blow by and oil vapor from inside the engine and re introduce it to the intake so it can be burned.

I wouldn't switch intakes for the RPM if you intend to use this truck as a daily driver.
The regular Performer keeps both sides of the carburetor separate improving booster venturi signal and low speed responsiveness.
As the name implies the RPM intake has larger volume runners and a notch in the plenum so it can flow more air at 6000+ rpm's.

I have the regular Performer on my engine.
It probably saves 40 or more pounds over the stock cast iron dual plane intake.

<a href="http://www.flickr.com/photos/24183730@N03/2341394102/" title="IMG_1896 by Jim_Urrata, on Flickr"><img src="http://farm4.static.flickr.com/3027/2341394102_0caa612693.jpg" width="500" height="375" alt="IMG_1896" /></a>

 

There is a soot covered elbow coming out where you are describing, I thought that connected to the air cleaner though. Its way bigger in diameter than the inlet on the carb though so would have to figure out how to reduce it.

Thanks!

Shane