carb problems? Everyones favorite.
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Junior User
Joined: Oct 2007
Posts: 79
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From: Aromas, CA
carb problems? Everyones favorite.
ok so I have a question about my carb.
When I cold start my 68 it will take a cupple of trys before it fires up. As in I have to stop and let the starter quit spinning before I turn the key. It takes about 3 or 4 times. But when its warm it fires right up or until the last day or so. Lately it has become more diffucult to start it even though its warm. Could it need a rebuild on the carb or what. I plan on replacing the carb with a holly 500 cfm four barrel and the intake in the early spring(or mabey sooner) to acheve better gas milage around town. It has the origonal Autolite 2 bbl on it so I'm thinking its almost wasted. I want it to be as relaiable as a 40 year old truck can be. Also I was wondering where or how I could get a teardown manual for this truck. Or at least a electrical/vacuum/carb diagram and schematics for these beasts.
Thanks to all who reply in advance.
Oh, and one more thing, On a different note, whats the origonal color that was used on the engine? I plan on replacing the waterpump and in doing so I want to paint the Timing cover and pump.
And thanks NumberDummy in advance for your post
!!!
I know you will give me the exact part number!!!!!
When I cold start my 68 it will take a cupple of trys before it fires up. As in I have to stop and let the starter quit spinning before I turn the key. It takes about 3 or 4 times. But when its warm it fires right up or until the last day or so. Lately it has become more diffucult to start it even though its warm. Could it need a rebuild on the carb or what. I plan on replacing the carb with a holly 500 cfm four barrel and the intake in the early spring(or mabey sooner) to acheve better gas milage around town. It has the origonal Autolite 2 bbl on it so I'm thinking its almost wasted. I want it to be as relaiable as a 40 year old truck can be. Also I was wondering where or how I could get a teardown manual for this truck. Or at least a electrical/vacuum/carb diagram and schematics for these beasts.
Thanks to all who reply in advance.
Oh, and one more thing, On a different note, whats the origonal color that was used on the engine? I plan on replacing the waterpump and in doing so I want to paint the Timing cover and pump.
And thanks NumberDummy in advance for your post
!!! I know you will give me the exact part number!!!!!
Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
hmm. mine does the opposite. in the cold morning i hop in, give the gas pedal a few pumps, pull the choke ****, turn the key and voila! fires like a champ.
its when the motor is hot on a hot day that i have to try 3 or 4 times and give it a rest for a few seconds like you are saying. good luck.
its when the motor is hot on a hot day that i have to try 3 or 4 times and give it a rest for a few seconds like you are saying. good luck.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
Originally Posted by big Red_25
As in I have to stop and let the starter quit spinning before I turn the key.
This is a starter problem, not a carb issue.
Fleet Mechanic
Joined: Aug 2007
Posts: 1,836
Likes: 261
From: Piney Woods of East Texas
These old truck on cold startup are very unique with out EFI. It takes a special touch. Mine requires 1 pump with the petal, choke on full, starts most every time when real cold. I have had others over the years that requre 2 pumps. When it is real cold the fuel does not atomizes very well. The reason you have to pump the petal a few times. And it is very hard to flood a cold engine, but can be done if you get carried away.
Now I would verify what Freightrain is trying to figure out. You may have a bad bendix/solenoid/corrosion on battery leads or even the cold cranking amps are low on the battery when cold.
As far as maunals one of the sponsors sell a DVD with all of the info you are looking for. There is little to no vacuum on these old truck. Just the distributer and Power brake booster if you have one. All of the dampers are cable control. Now the electrical is very weak, from day one. So if you having problems look for bad ground connections at all lights, the number one cause of things not working. Ford use a seperate ground connection for each light to the frame, these get corroded over the years. The other problem is voltage drop due to the very small gage wires. And the next problem is all of the connections out of the firewall. MFG no longer use these due to high resistance which cause voltage drops.
Now I would verify what Freightrain is trying to figure out. You may have a bad bendix/solenoid/corrosion on battery leads or even the cold cranking amps are low on the battery when cold.
As far as maunals one of the sponsors sell a DVD with all of the info you are looking for. There is little to no vacuum on these old truck. Just the distributer and Power brake booster if you have one. All of the dampers are cable control. Now the electrical is very weak, from day one. So if you having problems look for bad ground connections at all lights, the number one cause of things not working. Ford use a seperate ground connection for each light to the frame, these get corroded over the years. The other problem is voltage drop due to the very small gage wires. And the next problem is all of the connections out of the firewall. MFG no longer use these due to high resistance which cause voltage drops.
Junior User
Joined: Sep 2007
Posts: 62
Likes: 1
From: Patterson, CA
How are your ignition system components? A good tune up can work wonders. Check, adjust, replace as needed the cap, rotor, points, plugs, wires, air and fuel filters, etc...
If all is good there, I think the autolite and motorcraft 2bbls are the same (a little help here carb guys). If they are, they are SUPER easy to rebuild. I got a kit from NAPA for about $20. It took me about 1-2 hours to complete the whole process. Most of that time was thoroughly cleaning the interior/exterior and blowing out passages.
Mine now runs like a champ, except for a jetting issue that is causing a rich condition I'm working on. But you shouldn't have any jetting issues if it is the stock carb for your motor.
Defininately cheaper and easier than changing & tuning carb and manifold.
If all is good there, I think the autolite and motorcraft 2bbls are the same (a little help here carb guys). If they are, they are SUPER easy to rebuild. I got a kit from NAPA for about $20. It took me about 1-2 hours to complete the whole process. Most of that time was thoroughly cleaning the interior/exterior and blowing out passages.
Mine now runs like a champ, except for a jetting issue that is causing a rich condition I'm working on. But you shouldn't have any jetting issues if it is the stock carb for your motor.
Defininately cheaper and easier than changing & tuning carb and manifold.
Junior User
Joined: Sep 2007
Posts: 62
Likes: 1
From: Patterson, CA
Originally Posted by slow64
How are your ignition system components? A good tune up can work wonders. Check, adjust, replace as needed the cap, rotor, points, plugs, wires, air and fuel filters, etc...
If all is good there, I think the autolite and motorcraft 2bbls are the same (a little help here carb guys). If they are, they are SUPER easy to rebuild. I got a kit from NAPA for about $20. It took me about 1-2 hours to complete the whole process. Most of that time was thoroughly cleaning the interior/exterior and blowing out passages.
Mine now runs like a champ, except for a jetting issue that is causing a rich condition I'm working on. But you shouldn't have any jetting issues if it is the stock carb for your motor.
Defininately cheaper and easier than changing & tuning carb and manifold.
If all is good there, I think the autolite and motorcraft 2bbls are the same (a little help here carb guys). If they are, they are SUPER easy to rebuild. I got a kit from NAPA for about $20. It took me about 1-2 hours to complete the whole process. Most of that time was thoroughly cleaning the interior/exterior and blowing out passages.
Mine now runs like a champ, except for a jetting issue that is causing a rich condition I'm working on. But you shouldn't have any jetting issues if it is the stock carb for your motor.
Defininately cheaper and easier than changing & tuning carb and manifold.
Oh, I forgot, the exploded carb diagram come with the rebuild kit.
Thread Starter
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Junior User
Joined: Oct 2007
Posts: 79
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From: Aromas, CA
Thanks to all who have replied! I believe its not the starter or battery.
The engine cranks over just fine and the starter does not wherr N' such.
its just that its hard to get the engine to catch like it might not get enough fuel but I can smell it just fine when its running before it warms up.
I don't think I flood it when I start it because I can either try it with one pump with the petal or without and it has the same effect.
I can rebuild the carb and I know its cheeper and easier, but I was told, correct me if I'm wrong guys, but a 4bbl carb gets better gas milage around town than a 2bbl. At least thats what I was told by several people.
Thats the whole reason for the intended swap.
I have just given it a tuneup about a month a go and drive it here and there. It gets driven at least once a week or so. Just to keep it in operation, and some 30 minute trips thrown in on the weekend.
Someone had told me that the lack of vaccum hose on the air intake diaprahm that operates the trap door for exaust heat during cold starts was the curplit. I find that hard to believe but mabey he is right?
that would not change anything for initial startups because the exaust takes at least 30 to 40 secs before it starts to get warm. Could I be drawing too much air in for the cold start mix?
Its one of those things that just bugs me enough!!!!!!!
Thanks... Kevin
The engine cranks over just fine and the starter does not wherr N' such.
its just that its hard to get the engine to catch like it might not get enough fuel but I can smell it just fine when its running before it warms up.
I don't think I flood it when I start it because I can either try it with one pump with the petal or without and it has the same effect.
I can rebuild the carb and I know its cheeper and easier, but I was told, correct me if I'm wrong guys, but a 4bbl carb gets better gas milage around town than a 2bbl. At least thats what I was told by several people.
Thats the whole reason for the intended swap.
I have just given it a tuneup about a month a go and drive it here and there. It gets driven at least once a week or so. Just to keep it in operation, and some 30 minute trips thrown in on the weekend.
Someone had told me that the lack of vaccum hose on the air intake diaprahm that operates the trap door for exaust heat during cold starts was the curplit. I find that hard to believe but mabey he is right?
that would not change anything for initial startups because the exaust takes at least 30 to 40 secs before it starts to get warm. Could I be drawing too much air in for the cold start mix?
Its one of those things that just bugs me enough!!!!!!!
Thanks... Kevin
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Fleet Mechanic
Joined: Aug 2007
Posts: 1,836
Likes: 261
From: Piney Woods of East Texas
Most 4 barrel carbs have small primary cfm, as apposed to 2 barrels. This only applies if you keep the right food out of the secondaries. Vacuum secondaries are easier to setup, I prefer mechanicals. I run a very light return spring and feel the extra load of the secondaries. Spreadbore carbs generally have the smallest of the primaries, best economy. Intake has a lot to do with this too. Dual plane is what you need for low end response and town driving. A 3 duce with progressive linkage is one of the most fuel effiecent. But if your running these you are normally have a little extra under the hood.
The problem you indicate on hard to start when hot, can happen on several cases. You boil the fuel in the carb, causing starvation also know as vapor lock. The other can be a manifold leak, thermal induced. I have seen coils break down with heat. When your engine sits after being shutting down causes the core temp to raise as high as 240+F. This cause vapor lock, and other problems. Electric fuel pumps with return system at the regulator located at the carb helps keeps the fuel cooler.
So it's very hard to pin point. Adding thermal spacers are a start, I use them on mine. Higher octane fuel can help too.
The problem you indicate on hard to start when hot, can happen on several cases. You boil the fuel in the carb, causing starvation also know as vapor lock. The other can be a manifold leak, thermal induced. I have seen coils break down with heat. When your engine sits after being shutting down causes the core temp to raise as high as 240+F. This cause vapor lock, and other problems. Electric fuel pumps with return system at the regulator located at the carb helps keeps the fuel cooler.
So it's very hard to pin point. Adding thermal spacers are a start, I use them on mine. Higher octane fuel can help too.
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Junior User
Joined: Sep 2007
Posts: 62
Likes: 1
From: Patterson, CA
Factoring in the price of the new carb and manifold, If you are only driving it once a week, it won't be cost effective to swap out what you have. A rebuild will save you way more dough. Carbs are $300, manifolds $50-100 used, that's a lot of money to save a few nickels and dimes at the pump.
I can understand if you want something newer and fancier with the four barrel, but in my experience, if you have a four barrel, you end up using all four barrels.
That's why I opted to stay with my 2bbl. My right foot is way to heavy and my will power not so much...
I can understand if you want something newer and fancier with the four barrel, but in my experience, if you have a four barrel, you end up using all four barrels.
That's why I opted to stay with my 2bbl. My right foot is way to heavy and my will power not so much...
Thread Starter
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Junior User
Joined: Oct 2007
Posts: 79
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From: Aromas, CA
Originally Posted by slow64
That's why I opted to stay with my 2bbl. My right foot is way to heavy and my will power not so much...
thinks he's hot $#!t
I do see your points and such. Yes It will save me money at the pump but yes I have to have been driving it for quite some time to get money's worth!
Blue68100.... I have a question?
What do you mean by Duelplane? Is that a fancy smancy term for a type of manifold? and I think you are geting my problem confused with Danger_Dave.
His truck has a bad time starting when its hot. Mine takes a while to start hot or cold. But on hot tries, (when its been sitting for like 10 minutes or so) its been run up to normal O.T.
thanks for the answers
I'll look again tomarow for anything new if I have time!!!!
thanks........!! Kevin
Fleet Mechanic
Joined: Aug 2007
Posts: 1,836
Likes: 261
From: Piney Woods of East Texas
DualPlane manifolds are a type of intake design. The open single are design with one thing in mind, WOT..... No economy there.
I have a 1" insulator under mine and was thing about adding another. I also think if I go with electric fans and have them set to cool down after the engine is turned off. May help to keep the heat from building up.
I have a 1" insulator under mine and was thing about adding another. I also think if I go with electric fans and have them set to cool down after the engine is turned off. May help to keep the heat from building up.