Interchangeable carbs ?
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Senior User
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From: MT / WY
Interchangeable carbs ?
My 400 is running very poorly, I think possably too many vacuume leaks around the linkages. I also have a 300 Im going to rebuild to replace the 400 (in time).
Can I purchase a new 2 barrel carb for the 400 and use it on the 300 after the rebuild is done or should I just rebuild the carb on the 400 and get a different carb (2 barrel) for the 300 rebuild?
Can I purchase a new 2 barrel carb for the 400 and use it on the 300 after the rebuild is done or should I just rebuild the carb on the 400 and get a different carb (2 barrel) for the 300 rebuild?
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
It's not desirable to have a 2-barrel on a 300, because you either have to find an adapter to put it on the 1-barrel intake, or you have to upgrade to a 4-barrel intake and install a 2-barrel adapter (in which case you should just spring for the 4-barrel).
I'd spend some more time troubleshooting what you've got, because your suggestion for the problem's cause is very uncommon (if not unheard of). What are the exact symptoms, and what have you done to troubleshoot so far?
I'd spend some more time troubleshooting what you've got, because your suggestion for the problem's cause is very uncommon (if not unheard of). What are the exact symptoms, and what have you done to troubleshoot so far?
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From: MT / WY
WoW
I could have sworn that I saw a 2 bbl manifold listed for the 300. I guess my question is redundant now. Lol
I will ask questions about this carb after I work with it more. You say that vacuume leaks around the throttle linkages is not a common problem?
Ive had that problem with chebby carbs before, and a prof mechanic confirmed it. Maybe its just a chebby thing?
I know Ive fiddled with the fuel carb/manifold quite a bit but Im not having any luck finding the problem. Runns horrable as if a major vacuume leak but the starting fluid tests havent yeilded anything.
Bucks under throttle, gas smell in the exhaust, stalling at stops and idles rough.
All the EGR is removed and the manifolds locations have been thoroughly sealed and plugged. I ordered a vacuume gage and hoping to troubleshoot it more when it shows up.
I could have sworn that I saw a 2 bbl manifold listed for the 300. I guess my question is redundant now. Lol
I will ask questions about this carb after I work with it more. You say that vacuume leaks around the throttle linkages is not a common problem?
Ive had that problem with chebby carbs before, and a prof mechanic confirmed it. Maybe its just a chebby thing?
I know Ive fiddled with the fuel carb/manifold quite a bit but Im not having any luck finding the problem. Runns horrable as if a major vacuume leak but the starting fluid tests havent yeilded anything.
Bucks under throttle, gas smell in the exhaust, stalling at stops and idles rough.
All the EGR is removed and the manifolds locations have been thoroughly sealed and plugged. I ordered a vacuume gage and hoping to troubleshoot it more when it shows up.
Post Fiend
Joined: Dec 2007
Posts: 8,521
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From: Lost
Worn throttle shafts are more of a GM thing, it's rather rare with a ford carb, whether autolite/motorcraft or holley.
As for the 2bbl intake for a 300, I don't know of any. Factory used a 1 bbl, and most aftermarket are 4bbl. Putting a 2 bbl on the stock intake using an adapter rarely works well. On the other hand, putting the same 2bbl on an aftermarket 4bbl intake using an adapter has been done very successfully, many times.
The description of your issue sounds like either a float, needle & seat, or power valve issue. Bad float would have to be bought separately, but the needle & seat and power valve are included in nearly all carb rebuild kits, which range from $10 to $25 in most cases.
As for the 2bbl intake for a 300, I don't know of any. Factory used a 1 bbl, and most aftermarket are 4bbl. Putting a 2 bbl on the stock intake using an adapter rarely works well. On the other hand, putting the same 2bbl on an aftermarket 4bbl intake using an adapter has been done very successfully, many times.
The description of your issue sounds like either a float, needle & seat, or power valve issue. Bad float would have to be bought separately, but the needle & seat and power valve are included in nearly all carb rebuild kits, which range from $10 to $25 in most cases.
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From: MT / WY
Thanks :-)
Im not the best carb person so I spose its expected that thats where my problems would be. I have a friend with a couple good carbs, Maybe I can borrow one for a quick test. If thats not the problem I might be looking at pulling the valve covers and checking the cam lobes. The motor was rebuilt 30k ago but I have no idea what the quality of work the shade tree mechanic performed. I cant even say if the whole motor was rebuilt or just maybe the top end. Anyhow, I work two jobs so finding time to play with my old truck is tough to do. I will eventually get to it though. Thanks for your comments.
Im not the best carb person so I spose its expected that thats where my problems would be. I have a friend with a couple good carbs, Maybe I can borrow one for a quick test. If thats not the problem I might be looking at pulling the valve covers and checking the cam lobes. The motor was rebuilt 30k ago but I have no idea what the quality of work the shade tree mechanic performed. I cant even say if the whole motor was rebuilt or just maybe the top end. Anyhow, I work two jobs so finding time to play with my old truck is tough to do. I will eventually get to it though. Thanks for your comments.
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