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Let me first start by saying,
Yes, I do have a vv carb, and no Im not going to rip it off of the engine.
Previously I had a cheap crappy remake of a 2150 that the PO put on. It wasnt doing so well on my 1977 F100, and I thought I would take a gamble with a VV carb, a Motorcraft 2700 to be exact.
I bought it off of eBay, seller said that it was rebuilt and from a 302, and the engine in my truck is a 1980 255 v8. Once I got it I took it all apart and cleaned it, and it was in fact rebuilt. I put it all back together and followed one of those adjustment PDFs for the model.
Now its on the truck and it will start and run, but only for about 5-10 seconds. Then it very abruptly dies. Just wondering what the problem could be.
We had them on a bunch of 1980s Ford police cars with the 351W and AOD transmissions. I didn't learn a lot about them, but what I did gather was that they are NOT siumple stand alone carburetors ... they rely on a computor determining how far, when, and even how quick those venturi limiting plastic orbs open up. I remember that if I just stomped it to WOT like when working radar and going after one, it was actually slower accelerating than it was if I came out and not stomped on the gas but just smoothly continue to mash it to the floor. I was lucky, I only had my '81 a few months before I traded it in for a reissue older Plymouth when a buddy went undercover. Some guys had 2 or 3 over the course of the '80s.
The only kind of computerized function that my carb has is the cranking enrichment, which I dont have connected. I watched a video on youtube about how it didnt really matter, besides it doesnt get very cold here where I live.
The ones I saw used a throttle position sender to tell "something" how much the throttle was pressed, then "it" controled the venturi block things. It was a dog ... I could see 115 off North Mountain's 3 mile srtraight down grade, but only 105 on the flat. Had a Peterbilt once might near got away even.
In theory they sound great. In practice not so much. They came out around the same time as ethanol fuel here. The ethanol ate the rubber diaphragms. Shop rate didn't pay enough to diagnose, rebuild, replace and tune. The parts dept had a bolt on, hook up 2150. All you had to do was tell the parts guy you had a VV and
he would hand you a box with the 2150 in it. Sorry no help, never messed with them other than removal.
The 7200 VV is a feedback carburetor. The 7200s were easy to identify by the feedback actuator on the passenger side of the carb.
The feedback actuator bled small amounts of vacuum into the float bowl to alter the atmospheric pressure in the float bowl that pushed the fuel thru the carburetor.
Without the proper tools, water manometer, propane enrichment tool and jet adjusting tools its going to be tough to get one properly dialed in.
Hey CE. Any chance you can post a picture of your carburetor for us to see?
I’m not doubting you in any way, I’m just curious to see what the nonelectronic version looks like.
I was under the impression they all had throttle position sensors as well.
Very interested to see a mechanical one.
Thanks!
Does the “choke pull-off” canister function similar to a standard carb? Just wondering if by not pulling something open when the engine first fires up, it’s choking off the air.
I don't know anything about these carbs, but no need to have so many fuel filters. 2 showing and possibly a 3rd in the fuel inlet. Rule of thumb on Accel coils is they need to be mounted vertical.
Agree on the coils. The factory original Ford coils could be laid over reliably. But the aftermarket coil manufacturers all recommend a vertical placement.
Keeps them from overheating and burning out prematurely. But if yours has been that way for years perhaps you’re lucky and got one of the good ones.
The rod under the fuel line is the CER, cold enrichment rod.
These don't have chokes. When its cold the CER allows raw fuel directly into the venturis.
Those venturi valve looks like most of the teflon coating is gone. It acts as a vacuum seal against the two rollers under the cover.
It will not perform correctly if the teflon is worn off. They should be black.
Also, with the engine at 2000 rpm shine a timing light into the throat of the carburetor and see if the fuel is completely atomized as it comes off the metering rods or if there are drops of gas present.
If there are drops the most likely cause is going to be bad o-rings on the jets.
These are actually excellent carburetors. The problem with them is people were never properly trained to OH them, nor did they invest in the $450 special tools to do the job right..
In your video, is there a timing light nearby? Or was that some sparking I saw between a wire terminal and the vent on the top of the distributor cap?
Looked like a reflection of an oscillating light, but just thought I'd ask anyway.
The rod under the fuel line is the CER, cold enrichment rod.
These don't have chokes. When its cold the CER allows raw fuel directly into the venturis.
Thanks for the details. I actually figured as much, which is why I used quotation marks for my wording. But I did not know any of this for a fact.
Seeing a traditional choke spring housing with single wire, and a linkage with an apparent vacuum pull-off mechanism, made me think there was a mechanical aspect that partially opened those two flapper doodle thingies covering the venturii.
But again, I did not know anything about them.
So does the traditional "choke" mechanism do something entirely different and unrelated? Or does it do something about pulling on that CER to position it just right, so it knows when it's cold outside?
Enquiring minds and all that...
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