Engine Surges
Thread Starter
|
New User
Joined: Jun 1999
Posts: 3
Likes: 0
Engine Surges
I have a stock Lincoln 460 in my F100. Recently, after a long trip, I noticed that it has a 1 - 65 RPM surge. Which makes it hard for me to time and tune.
I've checked every vacuum source by spraying wd40 to see if the RPm will level out with no luck.
I was told last week that it could be my carb, and that it was to small. I currently have a holley 650 and was told that I should have a 750 to rrun properly. Can this really be a problem?
Can the surge be coming from within the carb?
Any comments are appreciated!
I've checked every vacuum source by spraying wd40 to see if the RPm will level out with no luck.
I was told last week that it could be my carb, and that it was to small. I currently have a holley 650 and was told that I should have a 750 to rrun properly. Can this really be a problem?
Can the surge be coming from within the carb?
Any comments are appreciated!
Senior User
Joined: Jun 1999
Posts: 265
Likes: 0
From: Greenville USA
Engine Surges
>I have a stock Lincoln 460 in
>my F100. Recently, after a
>long trip, I noticed that it
>has a 1 - 65 RPM
>surge. Which makes it hard for
>me to time and tune.
>I've checked every vacuum source by spraying
>wd40 to see if the RPm
>will level out with no luck.
>
>I was told last week that it
>could be my carb, and that
>it was to small. I
>currently have a holley 650 and
>was told that I should have
>a 750 to rrun properly.
>Can this really be a problem?
>Can the surge be coming from
>within the carb?
>Any comments are appreciated!
>
A 650 is right on the borderline IMHO, if driven normally and not revved it should be sufficient, but if you have performance aspirations, then a 750 would be better. As I seem to remember, surging is caused by vacuum leak or lean mixture. Since you seem to have ruled out a leak (check the intake manifold gasket carefully), I would suspec a little piece of junk is in your carb. If you are looking to replace it and need an excuse, this would be it, but you can probably clean and rebuild it and it will work fine.
George
>my F100. Recently, after a
>long trip, I noticed that it
>has a 1 - 65 RPM
>surge. Which makes it hard for
>me to time and tune.
>I've checked every vacuum source by spraying
>wd40 to see if the RPm
>will level out with no luck.
>
>I was told last week that it
>could be my carb, and that
>it was to small. I
>currently have a holley 650 and
>was told that I should have
>a 750 to rrun properly.
>Can this really be a problem?
>Can the surge be coming from
>within the carb?
>Any comments are appreciated!
>
A 650 is right on the borderline IMHO, if driven normally and not revved it should be sufficient, but if you have performance aspirations, then a 750 would be better. As I seem to remember, surging is caused by vacuum leak or lean mixture. Since you seem to have ruled out a leak (check the intake manifold gasket carefully), I would suspec a little piece of junk is in your carb. If you are looking to replace it and need an excuse, this would be it, but you can probably clean and rebuild it and it will work fine.
George
Senior User
Joined: Jun 1999
Posts: 222
Likes: 2
Engine Surges
If you mean that the surging is at idle and it is hard to time because the timing mark wanders, then my money would be on a worn timing chain. Without a vacuum leak, you could run a 400 cfm at idle without a problem; the larger cfm carb would primarily limit your maximum rpm. Once you get the timing mark stabilized, then adjusting the carb (assuming it is in good shape) should be easy. But with the initial timing all over the place, you will just be chasing your tuning setup and probably won't be happy with the results.
Thread
Thread Starter
Forum
Replies
Last Post
Mike Langan
1999 - 2016 Super Duty
0
May 2, 2017 09:12 PM
justastang99
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
7
May 20, 2016 09:43 PM
oldgameandfishdiesel
1999 - 2003 7.3L Power Stroke Diesel
9
Aug 18, 2009 12:05 AM
