Holley 390 cfm carb issues
Thread Starter
|
Senior User
Joined: Feb 2009
Posts: 117
Likes: 0
Holley 390 cfm carb issues
So bought the upgrade kit to 4 barrel on my 300 and now i am beginning to wish i would have stuck with the stock 1 barrel. with the troubles i had bolting on the headers and now the carb its making me regret it. anyway I bolted the carb on, hooked fuel line up, turned the key started it and turned off. repeated this process about 15 times and got the same respone. It just doesnt keep the truck running. any ideas on what i may have done wrong? i dont have the throttle cable hooked to it and maybe thats my problem, i dunno. thanks for the help
Junior User
Joined: Jun 2009
Posts: 76
Likes: 0
From: Fort Hood, TX
Well I just installed my new 390 yesterday and had no issues. you may have a vacuum leak, it could have a leak at the gasket between the carb and intake, the idle set screw could need to be adjusted, but hard to tell without knowing exactally what it is doing. A little more info would help to try and troubleshoot it, like does it just start and instantly die, have you tried to adjust the idle control screw, are all the vacuum lines hooked up?
Thread Starter
|
Senior User
Joined: Feb 2009
Posts: 117
Likes: 0
I am sure I do not have the Vacuum stuff hooked up correctly. I know now that i have vacuum ports on the side of the offenhauser manifold that are open. But basically i turn the key and it will run for 3 seconds and shut off.. I try to crank again and it acts like it wants to start but dont. Then i push the throttle piece on the carb a couple of times and it runs for about 3 seconds again. same thing happens each time i try. a couple of times it shot gas out the top of the carb
Thread Starter
|
Senior User
Joined: Feb 2009
Posts: 117
Likes: 0
what do you do to fix the open ports? they are just threaded holes. Forgive me for my lack of knowledge. I also noticed if i push the throttle on the carb that only 2 barrels open up the other 4 stay shut. I thought if you push it all the way open then all 4 open
Junior User
Joined: Jun 2009
Posts: 76
Likes: 0
From: Fort Hood, TX
with throttle 2 will open the back 2 are vacuum operated. If you have vacuum leaks it wont stay running especally at idle. will it stay running if you manually operate the throttle? if it will you may need to adjust the idle screw. but until you get the vacuum leaks fixed you will have problems. if the vacuum ports are not needed you can do a few things if it is a theaded hole or a hose run a bolt into it to block it. if it is a nipple put a small piece of hose on it with a bolt in the end. but make sure you have all your vacuum lines hooked up corectly before just capping things off or you may be chasing ghosts so to speak. what year is the truck?
Postmaster
Joined: Dec 2006
Posts: 3,603
Likes: 10
From: Spokane, WA
Any hardware store will have plugs for the holes in the manifold. IIRC the one toward the rear of the engine is smaller than the front hole so they will have to be appropriately sized. The set-up instruction sheet with the carb should be closely followed. If you do not have the sheet, start here: Holley Performance Products Frequently Asked Questions. All the information for Holley carbs can be found can be found through their Tech Service site.
Trending Topics
Thread Starter
|
Senior User
Joined: Feb 2009
Posts: 117
Likes: 0
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Yup, those two holes on the side of the intake, if they're open, are two massive vacuum leaks. There's no way it'll stay running if they're wide open. I imagine if you plug those, it'll fire right up.
Now that you have it converted to a 4bbl and don't have the stock stuff in there, you really don't need a lot of vacuum lines any more. If I remember right, you'll need:
-Big line running from the power brake booster to a big port on the intake or carb.
-Line running from the distributor vacuum advance to the carb.
-Big line running from the PCV to a big port on the intake or carb.
I think that's about it. Everything else should be capped off.
If I remember right, there's only one large port available on the carb, so you may need to get another one to put in one of those holes in the intake.
Something like this would work:
Just make sure it's the right size for the vacuum hose you'll be putting on it.
Don't get too frustrated with the 4bbl. It takes a bit of work to get it all set up sometimes. I know it did me. But I don't ever miss the 1bbl.
Now that you have it converted to a 4bbl and don't have the stock stuff in there, you really don't need a lot of vacuum lines any more. If I remember right, you'll need:
-Big line running from the power brake booster to a big port on the intake or carb.
-Line running from the distributor vacuum advance to the carb.
-Big line running from the PCV to a big port on the intake or carb.
I think that's about it. Everything else should be capped off.
If I remember right, there's only one large port available on the carb, so you may need to get another one to put in one of those holes in the intake.
Something like this would work:
Just make sure it's the right size for the vacuum hose you'll be putting on it.
Don't get too frustrated with the 4bbl. It takes a bit of work to get it all set up sometimes. I know it did me. But I don't ever miss the 1bbl.
Lead Driver
Joined: Jul 2009
Posts: 6,477
Likes: 19
From: Sheffield, AL
AbandonedBronco,
This may be a thread hijack, but is not intended to be.
I was looking at the most recent photo you have posted, referencing the PCV valve and I noticed something. Please keep in mind that I currently run a basicly stock engine with Carter YF, so I may be off base when addressing your Holley 390... you have a vacuum line going from the bottom of your carburetor to another nipple at the top. IF (?) the upper port serves the same function as on the Carter, which is to supply clean [filtered] air to the hard line which heats the air going to the original choke housing, which is being drawn by a small internal vacuum port, then with your current set-up [hose routing], wouldn't you have a vacuum leak?
This may be a thread hijack, but is not intended to be.
I was looking at the most recent photo you have posted, referencing the PCV valve and I noticed something. Please keep in mind that I currently run a basicly stock engine with Carter YF, so I may be off base when addressing your Holley 390... you have a vacuum line going from the bottom of your carburetor to another nipple at the top. IF (?) the upper port serves the same function as on the Carter, which is to supply clean [filtered] air to the hard line which heats the air going to the original choke housing, which is being drawn by a small internal vacuum port, then with your current set-up [hose routing], wouldn't you have a vacuum leak?
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
I believe it's supposed to be that way. Even though it was like that when I got it, you made me curious so I looked it up.
http://holley.com/data/Products/Tech...R8108-2rev.pdf
Looks like that's how it's hooked up on page 4.
Of course, I was hoping you were right for a second, because everything I can fix means one thing that'll run even better.
http://holley.com/data/Products/Tech...R8108-2rev.pdf
Looks like that's how it's hooked up on page 4.
Of course, I was hoping you were right for a second, because everything I can fix means one thing that'll run even better.