Freaking Emission System
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Freaking Emission System
Hi all, need some advice...
Had to re and re the intake manifold gasket on my '87 F250 which is carbureted. (That's why I'm here and not on the '87- forum.) Anyway I pulled most of the polution stuff off as it wasn't functioning anyway. Currently th struck sounds like crap until it warms up due to some funky emission related valve between the exhaust manifold and exhaust pipe on th driver's side. When it does warm up it tends to stall at idle. Mechanic suggested a non feedback carb so I got hold of a 600cfm Edelbrock and am waiting on the electric choke kit.
In short will changing the carb do the trick for a more drivable truck? What about that exhaust manifold valve thingy? Lastly I came across a '79 F250 with either a 302 or 351. Would that four barrel be a better choice over the Edelbrock and would exhaust manifolds from '79 work with my '87 351?
I like the truck but I just want it to run better! Thanks for all suggestions.
Had to re and re the intake manifold gasket on my '87 F250 which is carbureted. (That's why I'm here and not on the '87- forum.) Anyway I pulled most of the polution stuff off as it wasn't functioning anyway. Currently th struck sounds like crap until it warms up due to some funky emission related valve between the exhaust manifold and exhaust pipe on th driver's side. When it does warm up it tends to stall at idle. Mechanic suggested a non feedback carb so I got hold of a 600cfm Edelbrock and am waiting on the electric choke kit.
In short will changing the carb do the trick for a more drivable truck? What about that exhaust manifold valve thingy? Lastly I came across a '79 F250 with either a 302 or 351. Would that four barrel be a better choice over the Edelbrock and would exhaust manifolds from '79 work with my '87 351?
I like the truck but I just want it to run better! Thanks for all suggestions.
Last edited by 87-250; Aug 3, 2018 at 08:18 PM. Reason: spelling
Post Fiend
Joined: Feb 2008
Posts: 5,831
Likes: 121
From: St Albert, Alberta
Hi all, need some advice...
Had to re and re the intake manifold gasket on my '87 F250 which is carbureted. (That's why I'm here and not on the '87- forum.) Anyway I pulled most of th evolution stuff off as it wasn't functioning anyway. Currently th struck sounds like crap until it warms up due to some funky emission related valve between the exhaust manifold and exhaust pipe on th driver's side. When it does warm up it tends to stall at idle. Mechanic suggested a non feedback carb so I got hold of a 600cfm Edelbrock and am waiting on the electric choke kit.
In short will changing the carb do the trick for a more drivable truck? What about that exhaust manifold valve thingy? Lastly I came across a '79 F250 with either a 302 or 351. Would that four barrel be a better choice over the Edelbrock and would exhaust manifolds from '79 work with my '87 351?
I like the truck but I just want it to run better! Thanks for all suggestions.
Had to re and re the intake manifold gasket on my '87 F250 which is carbureted. (That's why I'm here and not on the '87- forum.) Anyway I pulled most of th evolution stuff off as it wasn't functioning anyway. Currently th struck sounds like crap until it warms up due to some funky emission related valve between the exhaust manifold and exhaust pipe on th driver's side. When it does warm up it tends to stall at idle. Mechanic suggested a non feedback carb so I got hold of a 600cfm Edelbrock and am waiting on the electric choke kit.
In short will changing the carb do the trick for a more drivable truck? What about that exhaust manifold valve thingy? Lastly I came across a '79 F250 with either a 302 or 351. Would that four barrel be a better choice over the Edelbrock and would exhaust manifolds from '79 work with my '87 351?
I like the truck but I just want it to run better! Thanks for all suggestions.
Post a pic of the emissions sticker with the vac hose routing. And we can get ya fixed up.
Lead Driver
Joined: Jul 2017
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From: San Jose, CA
I've seen some people prop the valve open (there's mechanical linkage and heating coil spring on the outside on some) and never think about it again.
Can't say if the new carb is going to fix anything or not. But at least it'll be very tunable by you if it doesn't. Hopefully it'll work right out of the box, but if not, maybe after some fiddling.
Paul
Can't say if the new carb is going to fix anything or not. But at least it'll be very tunable by you if it doesn't. Hopefully it'll work right out of the box, but if not, maybe after some fiddling.
Paul
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I've seen some people prop the valve open (there's mechanical linkage and heating coil spring on the outside on some) and never think about it again.
Can't say if the new carb is going to fix anything or not. But at least it'll be very tunable by you if it doesn't. Hopefully it'll work right out of the box, but if not, maybe after some fiddling.
Paul
Can't say if the new carb is going to fix anything or not. But at least it'll be very tunable by you if it doesn't. Hopefully it'll work right out of the box, but if not, maybe after some fiddling.
Paul
FTE Legend
Joined: Nov 2015
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From: Angier, NC
Ok that vacuum valve on the exh manifold to header pipe is a heat riser valve.
If everything is working right when the motor is cold the valve closes forcing hot gases up thru the intake manifold bypass to help heat it for cold weather first start up & driving till up to temp.
Once up to temp the valve opens and the exh gases go down the head pipe.
That valve has been known to rust open or closed. Closed is worst than open of the 2. They also leak at the pivot or if they use a gasket top and/or bottom they can leak.
If you want to remove it you can but you will need to fill the gap when removed. I don't know if there is a part with out the valve to fill the gap or not?
Could pull that one, gut it of the valve part and weld up the holes where the pivot goes thru the body and install it back.
Why I wanted to see the dist. I think you said some thing about a feed back carb, need to see picture of carb to make sure, and wonder if the dist. was a feedback also.
It does not look like a feedback type so good there.
On the carb we don't know what you have now, make or model, to say yes change it out or what.
Being you removed the so called "junk" what adjustments have you made to the motor, timing & carb to make it run better? The carb & timing were set for all the "junk" and when removed the factory setting no longer will work. They are a good starting place but that is it.
So with out a little more back ground on the carb & adjustments I think it would be hard to say if a carb swap is the best way to go.
Dave ----
If everything is working right when the motor is cold the valve closes forcing hot gases up thru the intake manifold bypass to help heat it for cold weather first start up & driving till up to temp.
Once up to temp the valve opens and the exh gases go down the head pipe.
That valve has been known to rust open or closed. Closed is worst than open of the 2. They also leak at the pivot or if they use a gasket top and/or bottom they can leak.
If you want to remove it you can but you will need to fill the gap when removed. I don't know if there is a part with out the valve to fill the gap or not?
Could pull that one, gut it of the valve part and weld up the holes where the pivot goes thru the body and install it back.
Why I wanted to see the dist. I think you said some thing about a feed back carb, need to see picture of carb to make sure, and wonder if the dist. was a feedback also.
It does not look like a feedback type so good there.
On the carb we don't know what you have now, make or model, to say yes change it out or what.
Being you removed the so called "junk" what adjustments have you made to the motor, timing & carb to make it run better? The carb & timing were set for all the "junk" and when removed the factory setting no longer will work. They are a good starting place but that is it.
So with out a little more back ground on the carb & adjustments I think it would be hard to say if a carb swap is the best way to go.
Dave ----
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That valve in the exhaust should not work and stay open if the vacuum line is disconnected. From his description of the problem, it sounds like it is still hooked up.
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The carb is original to the engine, '87. The valve is free after I loosened it up. Maybe I'll look into the gasket issue. I took th struck to a mechanic to make final adjustments and he said that due to the original carb, which was rebuilt about five years ago, it is as good as it will get. I was hesitant in removing the emissions equipment as I know they worked when new. However, finding someone to set it up correctly after PO had played with it has been really difficult so with a buggered Thermactor pump and other non functioning equipment I referred to all of it as junk. People should keep there hands off if they don't know what they are doing. I'm just trying to make the situation better. When it comes to carburetors my dad told me when I was in my early teens that "carburetor" was Latin for "keep your damn hands off!".
Post Fiend
Joined: Feb 2008
Posts: 5,831
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From: St Albert, Alberta
I was thinking of doing just that. I'll try to get pics of the valve and the emissions sticker. Where about sis that sticker by the way? The engine is a 351 with the one piece intake manifold gasket rather than the two piece type. I also removed the vacuum tree at the rear of the intake as it seemed to supply all th emissions stuff I took off.
And we will need to see a pic to the carb a couple different ones and styles were used.
FTE Legend
Joined: Nov 2015
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From: Angier, NC
So sounds like crap when cold and has a hard time idling when up to temp right?
I take it the plugs, wires, cap & rotor, air & fuel filters are in good shape?
Get the timing checked and set to factory as a start. May want to bump the timing up 2* to 4* BTDC and reset the carb as a start.
Unless the carb is junk and a rebuild will not fix it I don't see needing to replace it.
Will that other carb fit the intake on the motor now? If so you can give it a try to see if it is any better.
Dave ----
I take it the plugs, wires, cap & rotor, air & fuel filters are in good shape?
Get the timing checked and set to factory as a start. May want to bump the timing up 2* to 4* BTDC and reset the carb as a start.
Unless the carb is junk and a rebuild will not fix it I don't see needing to replace it.
Will that other carb fit the intake on the motor now? If so you can give it a try to see if it is any better.
Dave ----
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Ignition parts are OK. The stalling seems to occur when engine is up to temp. Mechanic set the timing but I may back it off a tad. Do the "ping" timing adjustment perhaps. When I tried to set timing it. Was nowhere needs the timing marks but it ran ok'ish. I'll post pics of the carb later today hopefully as well as the sticker with emissions info. Th emechanic suggested the different carb as it is a non emissions Edelbrock and will apparently bolt right in. Thanks for all the help and suggestions. Th Seagate continues...
Cargo Master
Joined: Dec 2004
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From: Florence, SC
A 1987 model with a 5.8/351 would not have had a feedback carburetor.
The last year for a feedback 5.8/351 was 1984. Ford dropped the 2V feedback carburetor and EEC-IV system for a 5.8L 4V H.O.motor with a standard Duraspark II ignition. This was used until 1987.
The last year for a feedback 5.8/351 was 1984. Ford dropped the 2V feedback carburetor and EEC-IV system for a 5.8L 4V H.O.motor with a standard Duraspark II ignition. This was used until 1987.
Post Fiend
Joined: Feb 2008
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From: St Albert, Alberta