[XrunDan]

Well, after MONTHS of trying to fix the running problem (gone through 2 distributors, and 2 carbs), I have been told I need a new carburetor. Right now I have a 600cfm Holley 4bbl. This carb, so I have been told, has a possible internal vacuum leak, and causes the idle to be erratic while in drive at a stop light.

This is the 2nd Holley to be on this engine, and both have been terrible. The first one leaked, even after a rebuild.

The engine is the factory 351 bored 0.30 over, with rebuilt heads, a mild grind cam (wish I could find the spec sheet), Edelbrock performer intake (4bbl setup instead of the factory 2bbl), and the Holley 600cfm carb. I was told that I may be over carbed, and therefore should look for a 550 cfm carb. I do NOT want to buy Holley, as my experience has been terrible, so I ask what brand of carburetor should I be looking into? I have never heard anything good about Edelbrock either, so I would like to avoid that as well.

 

[Cougrrcj]

600cfm vacuum secondary should be about right for a 351 inch motor. For a 289/302, you might want to go smaller, but I doubt it.

So you don't like Holley and you don't want Edelbrock. Well, that puts you out of 90% of the available carbs other than a stock FoMoCo 4-barrel carb. I've never tried an Edelbrock/Carter, and have never gotten an original Ford carb to run right on anything other than a 100% stock engine.

Chances are you either did not have your Holley hooked up correctly (ie you did have a PCV/breather plumbed to manifold vacuum, right?) or your vacuum lines are incorrect. If you didn't hook up a PCV, the carb is trying to meter the idle fuel/air 100% through the closed throttle blades. Not good. If you adjust to where throttle blades are slightly open, then you are adjusting things when the fuel transfer slots in the venturi are exposed and as a result proper idle/ initial throttle tip-in metering is out the window. That causes other issues like hesitation off-idle, the accelerator pump being slightly engaged, inconsistent idle, and so on.

Also, do NOT use the same 3/8" vacuum port for power brakes and PCV. If you do, your brake booster will become oil contaminated and the oil will attack/degrade the rubber diaphragm. Plumb one to the manifold tree fitting, and one to either a carb spacer or direct to the 3/8 port on the carb if so equipped.

 

[1970fastcat]

They are a little more expensive, but the best carbs out there are quick fuel. They are based on holley's design, olny improved. They use billet metering blocks so there is no issues with casting flaws. They have a vacuum secondary line called the street series. I think you would be real happy with one , I know I love mine.

 

[woodsnake]

I have both Holley and Edelbrock on all three of my cars. I prefer Holley, as they are just easier to mount up, and get adjusted. An internal vacuum leak could also be confused with an external vacuum leak.
What was the deal on both of the Holley's? One was rebuilt, but what about the other? A 600 Holley should be perfect on your car, I have used several set ups exactly like you are describing...

 

[CatHunter]

Sorry to twist yer arm, but I have a 1967 cougar XR7, running a 351C and it's been running an Edelbrock 750cfm carb since I got it and it never, ever ran right, always chocking out, always stalling etc. I blamed almost everything but the carb and just 2 days ago someone said, I know it's newer, but maybe you are over carbed (some folks don't believe in that), but I said yeah maybe and promptly purchased a brand new 600 cfm Holley 4-barrel. It took me about 20 minutes to remove and install the new carb. Just plug n play right out of the box, no tuning nothing and now my Cat runs like a dream! I couldn't believe the difference. It only cost me about $325.00 inc tax. Best purchase yet.... so you may want to reconsider your thoughts about Holley.

 

[woodsnake]

I buy them new, with out a choke at autozone everyday for like two hundred...(I've done it twice, the last one was 8 months ago)

 

[Jester1023]

This may ruffle a few feathers, but...it is my personal opinion that the standard Holley 600cfm, vacuum secondary carbutetor is a wheel chock. If you want a perfect street/mild performance carb, get an Edelbrock (Carter AFB design). They are extremely easy to tune and are not expensive. My only suggestion when running the AFB style carb is; run a good paper element fuel filter...the glass filters with the screen will let a gravel drive through them and the AFB carbs have their jets on the floor of the fuel bowls. By the way, I had my 600 Carter tuned to 17 mpg on my '70 .030" over 351C with a stock torque converter and 3.25 rear end...then I went out of my mind with anti-fuel economy mods.

 

[Jester1023]

Sorry to twist yer arm, but I have a 1967 cougar XR7, running a 351C and it's been running an Edelbrock 750cfm carb since I got it and it never, ever ran right, always chocking out, always stalling etc. I blamed almost everything but the carb and just 2 days ago someone said, I know it's newer, but maybe you are over carbed (some folks don't believe in that), but I said yeah maybe and promptly purchased a brand new 600 cfm Holley 4-barrel. It took me about 20 minutes to remove and install the new carb. Just plug n play right out of the box, no tuning nothing and now my Cat runs like a dream! I couldn't believe the difference. It only cost me about $325.00 inc tax. Best purchase yet.... so you may want to reconsider your thoughts about Holley.

How much for the Edelbrock? Depending on your engine mods, you may have been over carbed. What kind of fuel filter were you running?

 

[woodsnake]

A new 600 Edelbrock,from summit..
http://www.summitracing.com/parts/EDL-1406/

I just keep thinking there is something else going on here...Vacuum leak around the base of the carb, cracked vacuum line at the distributor, something else...

 

[Bad69cat]

Agreed - I wouldn't go plunking down $300 on a "maybe". Try to verify before you buy.....when you went through the carb did you check the metering surfaces for square - it's possible they got warped. Between the 2 you should be able to get it going. They aren't hard to rebuild - if you can get the metering blocks separated! Be sure to use the new blue gaskets so it won't stick from now on.......double check the floats and needles are actually set correct and working. There really isn't to much that can be wrong if all the passages are clean and sealed correctly...? Verify that you don't have any vac leaks anywhwere by blocking off everything - you should be able to kill the car by covering up the airhorn quite easily....if not you got a leak somewhere and follow the holley tuning guides posted on youtube.....

worst case is maybe you have to buy a new metering block.....but check it closely. Other than that, I seriously doubt you have an issue that isn't easily remedied.

 

[XrunDan]

alright......the 2nd carb (now on car) was brand new in box. I bought it about 6 mos ago. I am running a pcv that is connected to the large vacuum port on the rear of the carb. The only other vacuum line to the carb is a small line from the 3 port tree (at thermostat housing) to the metering block on the front of the carb (just behind the float bowl); all other vacuum ports on the carb are plugged. I have not noticed any other vacuum leaks, but I will check again this next weekend.

 

[woodsnake]

The ported vacuum hole is capped, right? Under the metering block, on the passenger side of the carb is another vacuum port. I would imagine you would hear it sucking air, but either way, it needs to be plugged off.
Have a look at post #7 here:

http://www.fordmuscleforums.com/c4-transmissions/501303-c4-2nd-3rd-gear-loop-sporadic.html

Take another good look at the vacuum hose ends for splits or brittle-ness...

Also..."causes the idle to be erratic while in drive at a stop light"

What exactly does this mean? Is it a choppy idle, that comes with the cam? ( doyou still have the cam specs?) Or are we looking at a couple of hundred RPM change while sitting?
Can you get a quick audio video of it doing this?

And, where exactly is your base timing and idle speed set? What is your idle RPM in gear?

 

[Cougrrcj]

Soooo, this car has manual brakes? You made no mention of vacuum line for power brakes. No mention of vacuum line for your headlight doors either.

Which Holley (list number or series) are you using? Use the ported vacuum outlet on the carb (2/3 the way up on the passenger side of the front metering block) and plumb that directly to the vacuum advance can of the distributor. With throttle closed, connecting this directly should not change timing or idle speed. If it does, the throttle blades are too far open and you're already sipping gas out of the intermediate fuel transfer slots. That makes adjusting anything problematic.

 

[woodsnake]

"engine" performance, in this case, can be assisted by unplugging ALL the vacuum off the engine, to isolate individual systems..Cap off all the vacuum from the engine, and take it in the around the block..But first lets get a number on timing and idle speed...

 

[xr7g428]

I am betting that the headlight door motors are leaking vacuum.

 

[XrunDan]

Soooo, this car has manual brakes? You made no mention of vacuum line for power brakes. No mention of vacuum line for your headlight doors either.

Which Holley (list number or series) are you using? Use the ported vacuum outlet on the carb (2/3 the way up on the passenger side of the front metering block) and plumb that directly to the vacuum advance can of the distributor. With throttle closed, connecting this directly should not change timing or idle speed. If it does, the throttle blades are too far open and you're already sipping gas out of the intermediate fuel transfer slots. That makes adjusting anything problematic.

Ah yes, I apologize, I was mentioning only the vacuum lines attached to the carb.

I hope to get the timing checked this weekend. It was timed by ear, so I dont know the number. The idle speed is about 600rpm, in Park, drops about 150rpm when put into gear. I bought the carbe brand new, but it did not come with the box. The only numbers i see are: on air horn 80457-6, just below that 2977; front driver side base of carb, 11242. I cannot find 80457-6 on the website, only 80457-1 and 80457-2. What carb did i buy?

 

[woodsnake]

It is a 600 cfm carb. I would really like to see what the numbers are on the cam as well. If it is around, oh say .476 your tuning specs won't change that much.
Is it this carb?

http://www.summitracing.com/parts/HLY-65-80457/


However.
Your initial timing needs to be a "known" factor. From here, I am thinking that your idle speed should be a bit higher, so that you are five or six hundred in gear. But again, timing will have a lot to do with that.
If you can isolate the engine from the rest of the car, we can diagnose better. So that means plug off ALL the vacuum from the engine. and see how the engine does then.

 

[woodsnake]

Also, just to get back on track,
what exactly is the "drive ability" problem?

 

[woodsnake]

I went back to see what all is going on with your car...
http://www.mercurycougar.net/forums/showthread.php?42765-knocking-under-load

http://www.mercurycougar.net/forums/showthread.php?45642-Idle-Issues

http://www.mercurycougar.net/forums/showthread.php?50448-update-still-need-help.

http://www.mercurycougar.net/forums/showthread.php?52922-Latest-news-on-running-problem... (post #12, pictures...)

http://www.mercurycougar.net/forums/showthread.php?55129-A-sad-day/page3

A few common things tha you are still trying to nail down.
#1 is timing.
#2, is timing.
#3 Make sure the carb is plugged off, and the distributor is not getting any vacuum to it.
Also, since
Looking at your carburetor mounting, it seems that you have bolts that go into the intake manifold, VS the studs that mount to the intake, and then get anchored with a nut.
Also
If that bolt is bottomed out, and not tight, that culd be the source of your vacuum leaks.
Here is a cheat sheet that shows 6 degree's initial.

http://www.carmemories.com/cgi-bin/viewexperience.cgi?experience_id=132
I can't find a quick sheet from the Ford manual today.

That is for 1969 fuel, on an engine with all the emissions equipment, new, functioning in place.
Yours, while rebuilt, is on different fuel, with the added benefit of a performance, camshaft, even if it is a "mild" grind.
You should set your initial at 10 degree's, then adjust the carburetor to get the best idle, in inches, of vacuum.
Then set your curb idle.
Also, you said you have been through two distributors. Can you post a picture of your engine, from the front of the car?
About where is your vacuum advance canister aligned?
fine tune as necessary. I.E., +/- a hundred rpm in gear, to compensate for coming off the freeway, and hitting a stop light.

 

[CatHunter]

How much for the Edelbrock? Depending on your engine mods, you may have been over carbed. What kind of fuel filter were you running?

Yes, one one hand I believe I was over carbed too .... on the other hand, the holley fit the bill immediately and didn't need any tuning right out of the box (as promised). I even checked all settings... was truly impressed.

I would sell my idlebrock for $100.00 it's supposedly close to new when I got my cougar. Even looks new... but I live in Canada and can't be bothered to ship it to far. Craigs list will get rid of it fast.