StingrayL82
Nampa, Idaho
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PolCat-76-Avion wrote:My question to the group is does the 76 Mopar 440 carburetor have a primer pump? If you pump the foot pedal does it pump gas into the carburetor throat? It has sat for a week and now will not start. It has an electric fuel pump on it so I let the pump run for awhile before trying to start it. Last weekend we went camping and when we went to leave it was a hard start.
Update: went out and let the fuel pump run for 2 more minutes and it started right up ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/smile.gif "smile")
If you are having to run the fuel pump that long to get it to start, the most likely culprit is going to be the fuel bowl well caps that sit underneath the phenolic resin bowl on the Thermo-Quad. I’m going through that right now and just bought some Loctite E AE–120HP resin to re-epoxy them. It’s almost identical to what Carter used when they were assembling them.
Fred
Retired Army Guy
2005 Monaco LaPalma 37PST
Workhorse W24 chassis
8.1L Vortec
Allison 2100 MH
Onyx Color Scheme
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PolCat-76-Avion
De Pere, Wis
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StingrayL82 would you have pictures of this? My experience is with vintage snowmobiles not larger carburetors.
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StingrayL82
Nampa, Idaho
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PolCat-76-Avion wrote:StingrayL82 would you have pictures of this? My experience is with vintage snowmobiles not larger carburetors.
Here you go. Keep in mind that there is an identical well cap on the other side of the bowl. Almost everything on the Thermo-Quad is siamesed.
![[image]](https://i.imgur.com/NKCWVyOl.jpg)
Of course, this is ASSuming that you still have the original Thermo-Quad on your 440, and not a replacement, like Holley or Quadrajet.
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eyeteeth
SW Michigan
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I recently re-built my Carb, re-glueing the well caps in an effort to solve the same problem. It did not. If you have a second guess, I'm open. Was starting the link the fuel line may just be old enough that its in need to replacement... But I can't figure out why that would cause problem with fuel that should already be available in the bowl.
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StingrayL82
Nampa, Idaho
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eyeteeth wrote:I recently re-built my Carb, re-glueing the well caps in an effort to solve the same problem. It did not. If you have a second guess, I'm open. Was starting the link the fuel line may just be old enough that its in need to replacement... But I can't figure out why that would cause problem with fuel that should already be available in the bowl.
From my extensive research on the subject, the aforementioned epoxy is the only one that seems to have success in keeping the well caps firmly in place and leak free. The key is to make sure that the old epoxy is completely removed from the fuel bowl and the caps, make sure that you give it a good key with some sandpaper, then clean with denatured alcohol, apply the epoxy, install the caps firmly, and let it cure for a couple of days, otherwise the ethanol will destroy the work you’ve done.
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PolCat-76-Avion
De Pere, Wis
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I found this on YouTube, it is what mine looks like.
https://www.youtube.com/watch?v=fzNhCLg9veg
Part II shows these tabs. 5:50 into the video.
https://www.youtube.com/watch?v=huzO53WB_1c
* This post was
edited 09/30/19 11:14am by PolCat-76-Avion *
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StingrayL82
Nampa, Idaho
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Yep, the venerable Thermo-Quad. When it’s properly built and tuned, it’s one of the best carburetors out there. There are many people out there who hate it, because they don’t know how to work on it. You’ll get arguments that the phenolic bowl cracks or warps. I have never seen one warp in my life and I’ve built quite a few. The reason they crack most of the time is because people either over tighten them or they forget that there are two screws that are down the primary bores and they try to use a screwdriver to pry it open.
If you take your time, and you use the factory service manual for your motorhome, you can get a really good running carburetor that gets decent mileage and gives you lots of power. Switching from a two barrel to the four barrel really woke my engine up. Plus, i really like the distinctive “moan” the Thermo-Quad makes, when the secondaries engage.
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PolCat-76-Avion
De Pere, Wis
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Went out at noon left fuel pump run til count of 10, full choke no pumping of the pedal. Started right up
The 3rd part of that video answered my question on the accelerator pump 4:35.
https://www.youtube.com/watch?v=L8CnQWTUSNU
* This post was
edited 09/30/19 12:08pm by PolCat-76-Avion *
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Ballenxj
Formerly Southern Nevada, Idaho now
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PolCat-76-Avion wrote:Went out at noon left fuel pump run til count of 10, full choke no pumping of the pedal. Started right up
It would seem you have now found your start up system. Congrats! ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/wink.gif "wink")
Downsizing ">
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PolCat-76-Avion
De Pere, Wis
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Not necessary but just annoying! Are the dash lights plug in bayonet style or the newer all glass style? Can you reach up and find them from behind?
This is the dash in it.
![[image]](https://live.staticflickr.com/65535/48833923563_c797b969d8_n.jpg)
* This post was
edited 10/02/19 04:07pm by PolCat-76-Avion *
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