So there's been a lot of first for me in the past week. I installed my first carburetor and, because I couldn't get the fuel filter canister off, I also installed my first mechanical fuel pump. For the most part this was all pretty straight forward as removing the old and replacing with new was a 1-to-1 operation.

All the same, I was absolutely shocked that after a few cranks on the starter the truck fired up and ran... but the idle speed was insane and I shut it down immediately.

So from those of you who've done this one or many times before, is this simply a matter of cranking down the idle speed screw or have I done something else wrong? The latter of which I'm completely willing to concede could have happened.

Carb is a Motorcraft 2100 on a 360 FE and I'm happy to fill in any other necessary details if needed.

Thanks very much in advance.

 

Make sure the throttle doesn't stick or isn't binding on something - like a thick gasket or something. Before starting the engine check that the throttle moves freely throughout its range and returns, and butterflies move to perfectly vertical no more no less when assistsnt floors pedal. Maybe back off on throttle adjustment a few turns and try again. Always keep a fire extinguisher ready and available in the truck, especially when working with a newly installed carburetor. Check that the fuel height in the bowl is correct once things settle down a bit.

 

A small amount of air gets pulled in through the 'fat leg' of the black choke housing. If it is missing the figure-8-like gasket, the hot-air tube, or the black-cap gasket, it could cause this.

When you get the RPMs down, water makes a good vacuum leak testing stream.

 

I'll take a look at that tomorrow morning. There was some interference in the linkage when I was working the Carb on the bench, but I wasn't sure how meaningful that was.

I do have a fire extinguisher though, so thank you as that's excellent advice as well.

I'm not entirely sure what this is. I simply took the hardline that came from the exhaust manifold and hooked it up there as it was on the original carb. It wasn't too carbon fouled so I assumed (ha!) it was okay. I don't recall any gasketing, but I also didn't take anything apart on the new carb.

 

There are some good ides on YouTube on the 2100. I suggest viewing a few of them for initial set up and adjustments like choke n idle settings.
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Hmm if the choke has been set by working the carb by hand the upper butterfly will close
almost shut.
This sets the Fast idea speed up to about 1800 rpm at startup.

All normal when a carb has been set up correctly. (edit)

Orich

 

Here's some good links to steps that have proved useful:

http://www.junkyardgenius.com/holley/tune01.html

http://www.bob2000.com/carb.htm

 

I'll be getting back at it soon so I appreciate all this advice. Hopefully this is an easy fix as I don't think it's healthy for the engine to rev that high even briefly.

I'll report back on my progress.

 

rebuilt carbs always need to be fine tuned to run correctly.
you will need to set the idle mixture screws , the choke fast idle , the idle speed.
you should also check dwell and timing to .
you tube videos will be a big help .

 

I figured it out, and it's embarrassing, but I'll admit my mistakes.

I had not reconnected the throttle return spring. I don't know why that didn't occur to me since it's pretty clear something ought to hook up to the shiny mounting boss intended for that purpose.

Of course something else had to go wrong so now the truck won't start at all. All I get is the brake light lighting up on the dash, but nothing else. So yay, electrical problems. :|

 

Look at this parts catalog pic between the choke body and carb for 9F577

This is the nylon fast idle cam which may have broken. Originally it was white, but over time, it begins to turn yellow.

2100 cam is the same for all V8: 1964/74 FoMoCo Passenger Cars; 1966/74 Bronco; 1967/74 F100/350 (with auto choke); 1969/74 Econoline.

 

Thank you kindly for the info. As it turned out, I'm something of a gifted idiot in that I can miss the blindingly obvious with almost no effort.

Or in other words, always reconnect the throttle return spring.

 

Check that your throttle return spring is installed. I disconnected mine by accident when I installed my electronic ignition and the first time I started it up I had to quickly shut it down as it tried to go to full throttle.