Assume you meant mpg?
1975 390fe rough idle.
Thread Starter
|
New User
Joined: Dec 2014
Posts: 22
Likes: 0
1975 390fe rough idle.
hello all, i have been having a issue with my truck. it is a f-150 with a 390 very mild build (rv cam/flat top pistons).
i have always had a somewhat rough idle and bad mileage....engine likes to surge a bit and shake at idle...also have never gotten over 9mph with this truck even though i drive like a granny....engine is equipped with edelbrock 1405 600cfm 4bbl
i have always had a somewhat rough idle and bad mileage....engine likes to surge a bit and shake at idle...also have never gotten over 9mph with this truck even though i drive like a granny....engine is equipped with edelbrock 1405 600cfm 4bbl
Thread Starter
|
New User
Joined: Dec 2014
Posts: 22
Likes: 0
with those numbers i havent done any tuning..that was stock carb calibration...today i checked plugs and they were white as if i was running lean...i went one step leaner as far as edelbrock instructions go and truck started making a diesely pop at idle...i went ahead and went two steps richer (one step above stock) and that went away still idles terribly and surges somewhat..will speed up for a fraction of a second and drop down at idle or low throttle...can also feel a bit of bucking at speed on hwy....
Posting Guru
Joined: Aug 2010
Posts: 1,761
Likes: 8
From: Knoxville, TN
By "steps" do you mean you're adjusting the idle mixture screws by some set amount, or that you're changing the jets or ... I see it's an Edelbrock - I think those also have metering rods? If the latter two, you'll have an impact on part/full throttle response, but not idle: the idle mixture control screws are what you need to start with.
Thread Starter
|
New User
Joined: Dec 2014
Posts: 22
Likes: 0
By "steps" do you mean you're adjusting the idle mixture screws by some set amount, or that you're changing the jets or ... I see it's an Edelbrock - I think those also have metering rods? If the latter two, you'll have an impact on part/full throttle response, but not idle: the idle mixture control screws are what you need to start with.
I have also set the mix using the idle screws....by ear, and using a vacuum gauge. Still idles rough.
Thread Starter
|
New User
Joined: Dec 2014
Posts: 22
Likes: 0
Yes, i have gone over all hoses. Checked gaskets...made sure carb was tight and went around base with carb cleaner.....no leaks....it also runs kinda hard at part throttle...im starting to think that even though its a new carb i need to pull it apart and rebuild it...
Trending Topics
Laughing Gas
Joined: Apr 2015
Posts: 877
Likes: 248
Have you looked at the ignition side then? Initial timing? Advance, etc?
Probably is the carb though, wouldn't hurt to look inside.
Probably is the carb though, wouldn't hurt to look inside.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
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
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
Thread Starter
|
New User
Joined: Dec 2014
Posts: 22
Likes: 0
thats all set stock. it doesnt run like its too advanced or retarded....its a very irregular stumbling idle that continues under light throttle.
Thread Starter
|
New User
Joined: Dec 2014
Posts: 22
Likes: 0
Problem is fixed, it was actually a irregular miss due to a plug with almost no gap on passenger side...must have fumbled when putting the plug end and pushed the gap closed....go figure, sometimes the problem is so simple you miss it. 
Thread
Thread Starter
Forum
Replies
Last Post
zsir
Fuel Injection, Carburetion & Fuel System
11
Apr 2, 2006 05:50 PM
FordTruckGuySTX
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
4
Mar 1, 2006 09:22 PM
killer4x4
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
3
Jul 9, 2001 01:35 PM