1977 140 carb replacement

jimmbo

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May 24, 2004
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You can can try a Universal Marine Carb from Holley, it will likely need some Tuning, and some Adapters to fit it in place of the Rochester.
It is the Smallest carb Holley offers, and is likely still way to big

Have you considered, cleaning and rebuilding the carb you have?
 

dubs283

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Jul 27, 2005
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You can rebuild your current carburetor if the housings are in good shape, no corrosion
 

Rayjmail

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I tore it apart there was corrosion on needle valves and power valve. kits dont have needle valves carb is 1351-5203A1 linkages and casting sleeves are worn and I can't get repeatability on idle. just wondering if there a sub for a $365+ rebuilt that will be a little less money and give me better performance.
 

Rayjmail

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That's what I was looking at already, thought there might br a better less expensive alternative. the ones I found had wrong bolt pattern.
 

bbook83

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There are lots of rebuilds out there. I believe the one jimmbo posted is a rebuild. The only “new” replacement I have found for the Rochester carbs for the 140s is the Sierra 18-7370n.
 

jimmbo

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You really don't have a lot of Options, as these are Marine Carbs. Don't get any Ideas of sticking on an auto/truck Carb in its place
 

jimmbo

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There are lots of rebuilds out there. I believe the one jimmbo posted is a rebuild. The only “new” replacement I have found for the Rochester carbs for the 140s is the Sierra 18-7370n.
It was a Rebuild, with an "update" to an Electric Choke.
 

Rayjmail

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Thanks for the input guys. The Sierra Carburator that you listed above is the one with the wrong bolt pattern. Anyways, you are correct there are not a lot of options out there. So once again, we break out the pocketbook.
 

bbook83

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You have identified two different base bolt pattern sizes. I was not aware of that. The Rochester on my 1974 140 has a 1 7/8” x 3 1/4“ bolt pattern, which I understand to be the “small” base. I don’t see the Sierra 18-7370n bolt pattern described anywhere. Do you know what it is? What is your bolt pattern?
 

1985 Century Mustang

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Get a rebuild kit. There are some good videos on YouTube that will help you accomplish this if you watch the video and take your time, check out the video below I had enclosed. I did mine as a newbie a few months ago. I was successful, and it's not that difficult if you watch it over and over extensively before you attempt it.

 
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jimmbo

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May 24, 2004
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I tore it apart there was corrosion on needle valves and power valve. kits dont have needle valves carb is 1351-5203A1 linkages and casting sleeves are worn and I can't get repeatability on idle. just wondering if there a sub for a $365+ rebuilt that will be a little less money and give me better performance.
If the Throttle Shafts are loose, and letting Air in, causing problem getting Consistent Idle, then the Carb is pretty much a Paper Weight. Corrosion on the Power Valve should be removable, with a bit of Polishing.
Every Carb Kit I have ever seen, included a Needle and Seat, for the Float Inlet. If you are referring to the Idle Mixture Screws, they only need replacing when someone insisted on overtighten them, instead of Lightly Seating them. Rebuilding a Carb includes careful Examination and Adjustment of Linkages to compensate for Wear
 

ScottinAZ

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Jun 25, 2009
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one of these will adapt your small base manifold to large base carbs..... I went down this route earlier this year with my carb.... the small base units are unobtanium in marine trim new, everyone uses the large base carbs....

 

Rayjmail

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Jun 20, 2023
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If the Throttle Shafts are loose, and letting Air in, causing problem getting Consistent Idle, then the Carb is pretty much a Paper Weight. Corrosion on the Power Valve should be removable, with a bit of Polishing.
Every Carb Kit I have ever seen, included a Needle and Seat, for the Float Inlet. If you are referring to the Idle Mixture Screws, they only need replacing when someone insisted on overtighten them, instead of Lightly Seating them. Rebuilding a Carb includes careful Examination and Adjustment of Linkages to compensate for Wear
It looks like this is the problem. I have purchased the i5Carb refurb I m hoping they are quality we"ll know soon. if not I'm going to go the route of adapter plate but I'm sure there are a lot of adjustments once you walk. away from OEM specs.
 

Rayjmail

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Jun 20, 2023
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You have identified two different base bolt pattern sizes. I was not aware of that. The Rochester on my 1974 140 has a 1 7/8” x 3 1/4“ bolt pattern, which I understand to be the “small” base. I don’t see the Sierra 18-7370n bolt pattern described anywhere. Do you know what it is? What is your bolt pattern?
the ones on amazon are 3 3/4X2 mine is like your 3 1/4 x 2 and I out checked the one I purchased from Marine carburetor and realized it is the wrong one its the same as amazon *!#& oh well back to the search!
 

Rayjmail

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Jun 20, 2023
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one of these will adapt your small base manifold to large base carbs..... I went down this route earlier this year with my carb.... the small base units are unobtanium in marine trim new, everyone uses the large base carbs....

t
Thanks Scott I will look into this!
 

bbook83

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Nov 6, 2004
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176
I got ahold of Marine Carburetor today they shipped me a rebuilt with the small base apparently they have both. very courteous and great to deal with we'll se hoew it runs in a couple of days.
I will be interested to hear how that carb works for you.
 
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