77 FORD TIMING ISSUES, QUESTIONS?
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
I did read where you had a new distributor, etc. No offence, but I've had a new distributor, fresh out of the box, with a bad vacuum advance can diaphragm.
Easy enough to check - just apply some vacuum to the vac advance line on the distributor (while the motor is running). A change in RPM will tell you it's good.
Easy enough to check - just apply some vacuum to the vac advance line on the distributor (while the motor is running). A change in RPM will tell you it's good.
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Freshman User
Joined: Oct 2010
Posts: 29
Likes: 0
From: AURORA, CO
Alright will do, I agree, I have received faulty parts in the past, more than once mind you...lol Tedster9, I've never tried that before, but seems like a liable check, so I just adjust the distributor for maximum manifold vacuum, then back it off an inch of pressure and that should be very close?... I'll have to give that a shot... Thanks for the info...
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Yes a vacuum gauge is one of the most useful tools in the drawer.
Set the idle up a little high when you do this, warmed up engine. Make sure vacuum advance is disconnected and plugged . Might as well set your idle mixture too. All interact with each other.
As you advance the distributor the vacuum indication and idle speed will increase up to a point. if you continue past this point idle will slow and start to wander.
About 1" of vacuum less than the highest is optimum, you can sort of hear the sweet spot. After you lock the dizzy down, check for ping on hard acceleration on the road. Might need to back off (retard) timing a bit more.
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Set the idle up a little high when you do this, warmed up engine. Make sure vacuum advance is disconnected and plugged . Might as well set your idle mixture too. All interact with each other.
As you advance the distributor the vacuum indication and idle speed will increase up to a point. if you continue past this point idle will slow and start to wander.
About 1" of vacuum less than the highest is optimum, you can sort of hear the sweet spot. After you lock the dizzy down, check for ping on hard acceleration on the road. Might need to back off (retard) timing a bit more.
Sent from my iPhone using IB AutoGroup
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
You need to follow the procedure for your carb application, but with my Holley, 2bl. the initial setting is to GENTLY turn in the idle mixture screws until they LIGHTLY seat, and then back off 1 and 1/4 turns on both sides. The reason for the caution is to avoid reefing the mixture screws tight in their seats, if they get buggered the mixture settings will never be right.
They are then adjusted inwards (typically); ...equal amounts until engine vacuum is highest, idle is smoothest, tho always favoring a slightly rich mixture.
You can do this by ear too but doing it with the gage gets it nuts on. The timing affects vacuum, and idle speed, idle speed affects mixture setting, mixture changes idle speed, etc, so it's a good way to observe how they interact. Hope this helps.
Sent from my iPhone using IB AutoGroup
They are then adjusted inwards (typically); ...equal amounts until engine vacuum is highest, idle is smoothest, tho always favoring a slightly rich mixture.
You can do this by ear too but doing it with the gage gets it nuts on. The timing affects vacuum, and idle speed, idle speed affects mixture setting, mixture changes idle speed, etc, so it's a good way to observe how they interact. Hope this helps.
Sent from my iPhone using IB AutoGroup
Thread Starter
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Freshman User
Joined: Oct 2010
Posts: 29
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From: AURORA, CO
Alright, well I got to work on the truck yesterday, got a vacuum gauge, set the timing using it as best I could, but when I did the air mixture screws, it's like no matter how much I turned them in or out, it really didn't change the vacuum... I have the old Motorcraft 2150 2 bbl, I know some carbs are backwards, ie adjusting all the way out turns off the fuel, anyone know which type this guy is, off in or out?... As for the whistling, I actually got up on the engine, and visually checked every vacuum hose there, and I'm thinking the carb is what's doing the whistling, not sure if it's supposed to, but the carb is maybe two weeks old since rebuild, and it did it before and after the rebuild, so not sure what's going on there, maybe it's supposed to whistle?...lol
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Freshman User
Joined: Oct 2010
Posts: 29
Likes: 0
From: AURORA, CO
Oh, but I must say that it does run better...lol When it's completely warmed up, restarting it is a bit of a hassle as it still acts like it's advanced too far, but according to the vaccum gauge, that's where it should be...
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Postmaster
Joined: Jan 2013
Posts: 3,512
Likes: 3
From: Panama City
Sounds like you have a carb problem. The idle mixture adjustment should make a big difference when adjusted. Maybe you have a bad base gasket. Maybe a gasket doesnt match up to a port hole in carb.Is the egr plate still on the manifold? Maybe it has a hole in it. I have seen at least 2 that had small holes burnt into them. Something is supplying air besides what needs to.
Post Fiend
Joined: Sep 2006
Posts: 14,325
Likes: 14
From: Island Southeast Alaska
I am with Allen again on this one. You have a vacuum leak somewhere for sure.
maybe more than one. If adjusting the low speed jets do nothing than it is getting
to much air. And a whistle is also an indication of a leak in as mush as air is being
sucked through a crack or gasket. Could be the intake manifold is cracked or the
gaskets are not sealed. Or anywhere in, on or under the carb. Is this the same
intake that was on the other engine? And the same carb only rebuilt?
maybe more than one. If adjusting the low speed jets do nothing than it is getting
to much air. And a whistle is also an indication of a leak in as mush as air is being
sucked through a crack or gasket. Could be the intake manifold is cracked or the
gaskets are not sealed. Or anywhere in, on or under the carb. Is this the same
intake that was on the other engine? And the same carb only rebuilt?
Post Fiend
Joined: Sep 2006
Posts: 14,325
Likes: 14
From: Island Southeast Alaska
Sorry but I can't edit my posts without shutting off my anti virus stuff.
Get a can of starting fluid and carefully spray around where the intake
meets the heads and around the carb base without it going into the carb.
While doing this and the engine speeds up a little ya have found where it is sucking air. Other stuff
will work like WD40 or other Panther **** but not as well as starting fluid. Some of
theses fluids can slow the engine when the leak is found and can make it
more difficult to locate it if your not used to testing in this way. But just use small sprays.
Don't just hold down the nozzle and empty the can. Be genital with it
and be careful.
Get a can of starting fluid and carefully spray around where the intake
meets the heads and around the carb base without it going into the carb.
While doing this and the engine speeds up a little ya have found where it is sucking air. Other stuff
will work like WD40 or other Panther **** but not as well as starting fluid. Some of
theses fluids can slow the engine when the leak is found and can make it
more difficult to locate it if your not used to testing in this way. But just use small sprays.
Don't just hold down the nozzle and empty the can. Be genital with it
and be careful.
Thread Starter
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Freshman User
Joined: Oct 2010
Posts: 29
Likes: 0
From: AURORA, CO
Sorry for the late reply fellas, I've been out of town working, which I do quite often...lol Alright, let's see if I can get all this answered...lol First of all, it is a different engine with a different intake, the carb is the same, it does have the egr plate under the carb, it just has a plug in the end of it though, no vacuum hoses going to it, and it does have the correct gasket lined up correctly for the port... I've considered spraying carb cleaner around it, but it's a brand new near show condition engine and I'm weary of it messing up the paint and such...lol But I have considered it...lol Since it's not being used, maybe I should just eliminate the egr valve and see if that improves anything?... Will all the linkage still mount and operately correctly without the 1" egr plate under the carb?... Or maybe I should just get a spacer for it to keep the carbs original height?...
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
At some point the smog regg'd carbs had the idle mixture screws backwards from "normal". Not sure what year that started. But you should have a definite, positive adjustment range where the mixture screws affect idle RPM and engine vacuum.
On Holleys, they even point out that turning them in all the way will stall the engine. If it doesn't stall, it generally means the power valve is bad. They get damaged by backfire through the carb. Recently made carbs don't have this problem anymore but it's something to be considered.
Carburetor mount nuts and the fuel bowl bolts should be checked now and then for proper torque. At only 60-80 in. lbs they tend to loosen. The fuel bowl bolts are even less, 25 in lbs, and these should be re-torqued prior to setting idle mixture.
On Holleys, they even point out that turning them in all the way will stall the engine. If it doesn't stall, it generally means the power valve is bad. They get damaged by backfire through the carb. Recently made carbs don't have this problem anymore but it's something to be considered.
Carburetor mount nuts and the fuel bowl bolts should be checked now and then for proper torque. At only 60-80 in. lbs they tend to loosen. The fuel bowl bolts are even less, 25 in lbs, and these should be re-torqued prior to setting idle mixture.