Project: Tow Tool
FTE Legend
Joined: May 2008
Posts: 56,542
Likes: 0
From: In my own world
nice job.
make sure you have vented fuel caps on that truck, or it will create a vacuum and do what you describe. The caps for that don't screw in, they twist in. screw in caps are for the efi's. I had that problem with a box truck I bought used years ago, and someone had changed the caps when they put the body on it.
make sure you have vented fuel caps on that truck, or it will create a vacuum and do what you describe. The caps for that don't screw in, they twist in. screw in caps are for the efi's. I had that problem with a box truck I bought used years ago, and someone had changed the caps when they put the body on it.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 40
From: EXTREME southwest CT
Hmmm,
I have screw in caps from the factory on my carbureted 460 with a mechanical fuel pump.
I know they hold pressure, because they are tested every year at the emissions station.
I don't know if they are one way to eliminate a chance of vacuum.
When I had to replace them last year I used the Motorcraft FC 920 caps from Amazon. They were on sale for about $10
I have screw in caps from the factory on my carbureted 460 with a mechanical fuel pump.
I know they hold pressure, because they are tested every year at the emissions station.
I don't know if they are one way to eliminate a chance of vacuum.
When I had to replace them last year I used the Motorcraft FC 920 caps from Amazon. They were on sale for about $10
Thread Starter
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Senior User
Joined: Sep 2011
Posts: 442
Likes: 1
From: Roanoke, VA
Not yet. It only does it for a couple gallons. Which is only an issue when both tanks are full. I'm going to pull the valve and clean it. There is a check valve in the switch that should prevent this. If that doesn't work then I'll get the place where I bought it to see if they'll replace it.
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Senior User
Joined: Sep 2011
Posts: 442
Likes: 1
From: Roanoke, VA
So I got it running fairly good. Carb is right. I recurved the Duraspark II. That's helped with getting it going. It still hesitates when I come off idle. Not alot and the recurving and some carb tuning has helped it, but it still does it. Once it's off of idles it runs great. It also happens if I'm coasting in a gear then put it on the floor, hesitates then runs like a raped ape.
The last thing is the vacuum advance. Could this not functioning cause a hesitation? How do I test and set this thing?
The last thing is the vacuum advance. Could this not functioning cause a hesitation? How do I test and set this thing?
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 40
From: EXTREME southwest CT
You can test it, but I would suggest you check into your accelerator pump adjustment and shot.
There are different orifices and cams in addition to the pump arm adjustment.
Check the timing with the vacuum disconnected and plugged.
Then connect it to full manifold vacuum and see how much difference there is.
Here are the full instructions for adjusting the old Crane 99607-1 kit.
http://www.jegs.com/InstallationInst...70-99607-1.pdf
The tuning section begins at the end of page 3.
Hope this helps.
There are different orifices and cams in addition to the pump arm adjustment.
Check the timing with the vacuum disconnected and plugged.
Then connect it to full manifold vacuum and see how much difference there is.
Here are the full instructions for adjusting the old Crane 99607-1 kit.
http://www.jegs.com/InstallationInst...70-99607-1.pdf
The tuning section begins at the end of page 3.
Hope this helps.
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Joined: Oct 2010
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From: Missouri
My old 4180 had severe hesitation that I never got fixed before replacing the carb. Upgrading to a #31 accelerator pump discharge nozzle helped but did not fix the problem. For a 460 you could probably skip to one of the next sizes up. (Stock size is #28) I never messed with the pump cams, but I know there is improvement to be made.
If the vacuum advance is really slow to react then I can see how it's possible to cause a slight hesition. Maybe look at your vacuum diagram too and see if you have it connected the same way as the factory had it.
If the vacuum advance is really slow to react then I can see how it's possible to cause a slight hesition. Maybe look at your vacuum diagram too and see if you have it connected the same way as the factory had it.
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Senior User
Joined: Sep 2011
Posts: 442
Likes: 1
From: Roanoke, VA
My old 4180 had severe hesitation that I never got fixed before replacing the carb. Upgrading to a #31 accelerator pump discharge nozzle helped but did not fix the problem. For a 460 you could probably skip to one of the next sizes up. (Stock size is #28) I never messed with the pump cams, but I know there is improvement to be made.
If the vacuum advance is really slow to react then I can see how it's possible to cause a slight hesition. Maybe look at your vacuum diagram too and see if you have it connected the same way as the factory had it.
If the vacuum advance is really slow to react then I can see how it's possible to cause a slight hesition. Maybe look at your vacuum diagram too and see if you have it connected the same way as the factory had it.
Also after some testing the diaphragm is bad for the vacuum assist so I'm getting one of those to put on as well. Every little thing I do helps so we'll see.
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Senior User
Joined: Sep 2011
Posts: 442
Likes: 1
From: Roanoke, VA
Well long story I went over everything and realized I had some things messed up. Mainly I had a vacuum line off the manifold going into the carb. I was told it was for choke pulloff on the EGR carb. Nope it isn't. It is for EGR and should be vented to the charcoal canister. So I did that. Now I don't have the vacuum leak. Stupid.
I also rejetted form #61 to #64 jets. And went from a #28 Acc pump to #31 acc pump. I will be getting a new power valve as well. I have a 6.5. I need a 8.5. Sizing is based on half of manifold vacuum. My manifold vacuum is 17. The 6.5 won't start to open until 13 (double the rated value). As a result the manifold vacuum has to get to 13 before it adds fuel. So that could lead to some power loss as well.
I also rejetted form #61 to #64 jets. And went from a #28 Acc pump to #31 acc pump. I will be getting a new power valve as well. I have a 6.5. I need a 8.5. Sizing is based on half of manifold vacuum. My manifold vacuum is 17. The 6.5 won't start to open until 13 (double the rated value). As a result the manifold vacuum has to get to 13 before it adds fuel. So that could lead to some power loss as well.
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Senior User
Joined: Sep 2011
Posts: 442
Likes: 1
From: Roanoke, VA
So my plugs were fouled so I changed them and rejetted down 2 sizes from the #64 to the #62. As a result I had to go through the idle circuit again, set up floats etc etc. Also while I had it off I made a block off plate for my EGR. For all I know the valve was leaking and exhaust was getting into the intake.
There is still a slight hesitation but it's easy to drive around. So I'm calling the motor done (for now). I need to put in my brake controller and continue to change out filters until all the crud is out of the tanks.
Also had to put a heater core in so I changed the hoses going to the heater core as well.
Now I'll be slowly doing the cosmetic stuff.
There is still a slight hesitation but it's easy to drive around. So I'm calling the motor done (for now). I need to put in my brake controller and continue to change out filters until all the crud is out of the tanks.
Also had to put a heater core in so I changed the hoses going to the heater core as well.
Now I'll be slowly doing the cosmetic stuff.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 40
From: EXTREME southwest CT
Did you fix your vacuum advance?
Mine is out and causing all the symptoms you mentioned.
(Amazon shipped within 2 hours of placing my order
)
You need to understand how, and why, Holley's power valves work.
A wideband O2 sensor can help in tuning if you don't care for their simplified instructions.
Mine is out and causing all the symptoms you mentioned.
(Amazon shipped within 2 hours of placing my order
)You need to understand how, and why, Holley's power valves work.
A wideband O2 sensor can help in tuning if you don't care for their simplified instructions.
Junior User
Joined: Sep 2011
Posts: 59
Likes: 0
From: Whitehouse, Tx
I'm interested in the bucket seats I'd love to take the brench out of my single cab and put some bucket seats and a console in it. Do you already have the seats if so where did you get them from?